A comparative study of volumetric analysis, histopathologic downstaging, and tumor regression grade in evaluating tumor response in locally advanced rectal cancer following preoperative chemoradiation

The MRI radiomics signature can predict the pathologic response to neoadjuvant chemotherapy in locally advanced esophageal squamous cell carcinoma

OBJECTIVES

To investigate the MRI radiomics signatures in predicting pathologic response among patients with locally advanced esophageal squamous cell carcinoma (ESCC), who received neoadjuvant chemotherapy (NACT).

METHODS

Patients who underwent NACT from March 2015 to October 2019 were prospectively included. Each patient underwent esophageal MR scanning within one week before NACT and within 2-3 weeks after completion of NACT, prior to surgery. Radiomics features extracted from T2-TSE-BLADE were randomly split into the training and validation sets at a ratio of 7:3. According to the progressive tumor regression grade (TRG), patients were stratified into two groups: good responders (GR, TRG 0 + 1) and poor responders (non-GR, TRG 2 + 3). We constructed the Pre/Post-NACT model (Pre/Post-model) and the Delta-NACT model (Delta-model). Kruskal-Wallis was used to select features, logistic regression was used to develop the final model.

RESULTS

A total of 108 ESCC patients were included, and 3/2/4 out of 107 radiomics features were selected for constructing the Pre/Post/Delta-model, respectively. The selected radiomics features were statistically different between GR and non-GR groups. The highest area under the curve (AUC) was for the Delta-model, which reached 0.851 in the training set and 0.831 in the validation set. Among the three models, Pre-model showed the poorest performance in the training and validation sets (AUC, 0.466 and 0.596), and the Post-model showed better performance than the Pre-model in the training and validation sets (AUC, 0.753 and 0.781).

CONCLUSIONS

MRI-based radiomics models can predict the pathological response after NACT in ESCC patients, with the Delta-model exhibiting optimal predictive efficacy.

CLINICAL RELEVANCE STATEMENT

MRI radiomics features could be used as a useful tool for predicting the efficacy of neoadjuvant chemotherapy in esophageal carcinoma patients, especially in selecting responders among those patients who may be candidates to benefit from neoadjuvant chemotherapy.

KEY POINTS

• The MRI radiomics features based on T2WI-TSE-BLADE could potentially predict the pathologic response to NACT among ESCC patients. • The Delta-model exhibited the best predictive ability for pathologic response, followed by the Post-model, which similarly had better predictive ability, while the Pre-model performed less well in predicting TRG.

Downstaging in Advanced Rectal Cancers: A Propensity-Matched Comparison Between Short-Course Radiotherapy Followed by Chemotherapy and Long-Course Chemoradiotherapy

BACKGROUND

Short-course radiotherapy followed by chemotherapy has not been widely evaluated as an alternative to traditional long-course chemoradiotherapy in locally advanced rectal cancer.

OBJECTIVE

This study compared the oncological and short-term outcomes between short-course radiotherapy + chemotherapy and long-course chemoradiotherapy in locally advanced rectal cancer.

DESIGN

This is a retrospective propensity-matched study.

SETTINGS

The study was conducted in a colorectal department at a tertiary care oncology center in India.

PATIENTS

There were 173 patients. Group A had 47 patients and group B had 126 patients. A 1:2.7 matching was done for age, sex, distance of tumor from the anal verge, sphincter preservation surgeries, MRI-based pretreatment T stage, and circumferential resection margin.

INTERVENTIONS

The interventions performed were short-course radiotherapy + chemotherapy (group A) and long-course chemoradiotherapy (group B) in locally advanced rectal cancer.

MAIN OUTCOME MEASURES

The primary measures were pathological circumferential resection margin positivity, downstaging, tumor regression grade, and postoperative complications.

RESULTS

Of the patients, 52% had a positive circumferential resection margin on MRI, 57% had low rectal tumors, and 20% had T4 tumors. Distribution of rectal surgeries was similar between the 2 groups. pT downstaging and tumor regression scores were significantly better in group B ( p = 0.028 and 0.026). Pathological circumferential resection margin, distal resection margin, and nodal yield were similar. On multivariate analysis, pretreatment N status was the only independent predictive factor for pathological circumferential resection margin status. Grade 3 to 4 Clavien-Dindo complications, anastomotic leak rates, and hospital stay were similar between the 2 groups.

LIMITATIONS

This was a retrospective study. Although propensity matching was performed, selection bias cannot be eliminated completely, as seen in the difference in the surgical approaches between the 2 groups.

CONCLUSIONS

In a cohort containing a significant portion of MRI circumferential resection margin-positive low rectal cancers, short-course radiotherapy + chemotherapy followed by delayed surgery resulted in lower T downstaging and lower tumor regression scores compared with long-course chemoradiotherapy, but pathological circumferential margin status, distal resection margin, nodal yield, and perioperative morbidity were similar between the 2 groups. This suggests that short-course radiotherapy + chemotherapy could be a viable alternative to long-course chemoradiotherapy in locally advanced rectal cancers. See Video Abstract at http://links.lww.com/DCR/B855 .

REDUCCIN DEL ESTADIO EN LOS CNCERES RECTALES AVANZADOS UNA COMPARACIN DE PROPENSIN EQUIPARADA ENTRE LA RADIACIN DE CICLO CORTO SEGUIDA DE QUIMIOTERAPIA Y LA QUIMIO RADIACIN DE CICLO LARGO

ANTECEDENTES:La radioterapia de ciclo corto seguida de quimioterapia no ha sido evaluada ampliamente como una alternativa a la tradicional quimio radioterapia de ciclo largo en el cáncer de recto localmente avanzado.OBJETIVO:Estudio que compara los resultados oncológicos y a corto plazo entre la radioterapia de ciclo corto + quimioterapia y la quimio radioterapia de ciclo largo en el cáncer de recto localmente avanzado.DISEÑO:Estudio comparado de propensión de manera retrospectiva.AJUSTE:Departamento colorrectal en un centro de atención oncológica de tipo terciario en la India.PACIENTES:Hubo 173 pacientes. El grupo A tenía 47 y el grupo B tenía 126 pacientes. Se realizó una comparación de 1: 2,7 para edad, sexo, distancia del tumor desde el margen anal, cirugías de preservación del esfínter, estadio T previo al tratamiento basada en resonancia magnética y margen de resección circunferencial (CRM).INTERVENCIONES:Radioterapia de ciclo corto + quimioterapia (grupo A) y quimio radioterapia de ciclo largo (grupo B) en cáncer de recto localmente avanzado (LARC).PRINCIPALES MEDIDAS DE RESULTADO:Positividad histopatológica de CRM, reducción del estadio tumoral, grado de regresión tumoral, complicaciones posoperatorias.RESULTADOS:El 52% de los pacientes han tenido un margen de resección circunferencial positivo en la resonancia magnética, 57% de tumores rectales bajos, 20% de tumores T4. La distribución de cirugías rectales fue similar entre los 2 grupos. Las puntuaciones de regresión tumoral y de reducción del estadio de pT fueron significativamente mejores en el grupo B ( p = 0.028 y 0.026 respectivamente). El margen de resección circunferencial patológico, el margen de resección distal y los ganglios arrojados fueron similares. En el análisis multivariado, el estadio N previo al tratamiento fue el único factor predictivo independiente para el estadio de pCRM. Las complicaciones Clavien-Dindo de grado 3-4, las tasas de fuga anastomótica y la estancia hospitalaria fueron similares entre los dos grupos.LIMITACIONES:Retrospectiva; aunque la propensión coincide, existe potencial sesgo de selección.CONCLUSIONES:En una cohorte que contenía una porción significativa de cánceres rectales bajos con margen de resección circunferencial positivo por resonancia magnética, la radioterapia de ciclo corto + quimioterapia seguida de cirugía tardía dio como resultado una mayor reducción del estadio T y de regresión tumoral en comparación con la quimio radioterapia de ciclo largo. Pero el estatus histopatológico del margen circunferencial, el margen de resección distal, el rendimiento ganglionar y la morbilidad perioperatoria fueron similares entre los dos grupos. Esto sugiere que la radioterapia de ciclo corto + quimioterapia podría ser una alternativa viable a la quimio radioterapia de ciclo largo en cánceres rectales localmente avanzados. Consulte Video Resumen en http://links.lww.com/DCR/B855 . (Traducción-Dr. Osvaldo Gauto ).

Rectal Signet Ring Cell Carcinoma: Post-Chemoradiotherapy Evaluation by MRI and Corresponding to Pathology

Background

Signet ring cell carcinoma (SRCC) is recognized as an uncommon subtype of colorectal carcinoma (CRC). It showed characteristic magnetic resonance imaging (MRI) manifestations. However, the MRI features post-chemoradiotherapy (CRT) were not reported, and it is unknown whether the current tumor regression grade (TRG) system by MRI (mrTRG) is applicable to SRCC.

Purpose

To summarize the image features of rectal SRCC on post-CRT images corresponding to the pathology, and to determine the predicting value of mrTRG compared with TRG by pathology (pTRG).

Methods

We retrospectively enrolled seven patients (male: female = 3:4; mean age, 45.1 years) with biopsy-pathology proved SRCC, who underwent pre- and post-CRT MR imaging followed by surgery. An experienced gastrointestinal radiologist accessed mrTRG using a 5-point grading system by mandard standard on T2 weighted image (T2WI) and then added diffusion weighted image (DWI) in a 1-month interval. Additionally, MRI features were recorded on pre- and post-CRT images as follows: pattern (target sign) and main signal intensity of T2WI, characterized manifestation of DWI, and mean Apparent Diffusion Coefficient (ADC)values. The mrTRG and all MR image features were compared to the post-operative pathology.

Results

At post-CRT histology, five patients got a good response (TRG 1, n = 4; TRG 2, n = 1), one patient got a partial response, and one patient got a poor response. The accuracy of MRI predicted the pathology response by mandard standard was 14% and increased to 71.4% when added DWI. After CRT, different degrees of homogeneous high SI without enhancement representing acellular mucin were observed in all patients, and the thick-ring high SI turned into a thin-target sign in most good responders. Moreover, the tumor volume decreased or slightly increased in good responders, while it markedly increased in the partial and poor responder by 57% and 73.8%, respectively.

Conclusion

Homogeneous high SI on T2WI and thin target sigh on DWI were the main MRI changes of RSRCC, which was corresponding to the mucinous regression and represents for good response post-CRT. The mrTRG and tumor volume was not a reliable indicator to the pathology response. We considered that DWI should be added to T2WI to evaluate RSRCC response to CRT.

Complete Response Evaluation of Locally Advanced Rectal Cancer to Neoadjuvant Chemoradiotherapy Using Textural Features Obtained from T2 Weighted Imaging and ADC Maps

BACKGROUND

The prediction of pathological responses for locally advanced rectal cancer using magnetic resonance imaging (MRI) after neoadjuvant chemoradiotherapy (CRT) is a challenging task for radiologists, as residual tumor cells can be mistaken for fibrosis. Texture analysis of MR images has been proposed to understand the underlying pathology.

OBJECTIVE

This study aimed to assess the responses of lesions to CRT in patients with locally advanced rectal cancer using the first-order textural features of MRI T2-weighted imaging (T2-WI) and apparent diffusion coefficient (ADC) maps.

METHODS

Forty-four patients with locally advanced rectal cancer (median age: 57 years) who underwent MRI before and after CRT were enrolled in this retrospective study. The first-order textural parameters of tumors on T2-WI and ADC maps were extracted. The textural features of lesions in pathologic complete responders were compared to partial responders using Student's t- or Mann-Whitney U tests. A comparison of textural features before and after CRT for each group was performed using the Wilcoxon rank sum test. Receiver operating characteristic curves were calculated to detect the diagnostic performance of the ADC.

RESULTS

Of the 44 patients evaluated, 22 (50%) were placed in a partial response group and 50% were placed in a complete response group. The ADC changes of the complete responders were statistically more significant than those of the partial responders (P = 0.002). Pathologic total response was predicted with an ADC cut-off of 1310 x 10-6 mm2/s, with a sensitivity of 72%, a specificity of 77%, and an accuracy of 78.1% after neoadjuvant CRT. The skewness of the T2-WI before and after neoadjuvant CRT showed a significant difference in the complete response group compared to the partial response group (P = 0.001 for complete responders vs. P = 0.482 for partial responders). Also, relative T2-WI signal intensity in the complete response group was statistically lower than that of the partial response group after neoadjuvant CRT (P = 0.006).

CONCLUSION

As a result of the conversion of tumor cells to fibrosis, the skewness of the T2-WI before and after neoadjuvant CRT was statistically different in the complete response group compared to the partial response group, and the complete response group showed statistically lower relative T2-WI signal intensity than the partial response group after neoadjuvant CRT. Additionally, the ADC cut-off value of 1310 × 10-6 mm2/s could be used as a marker for complete response along with absolute ADC value changes within this dataset.

MRI radiomics in the prediction of therapeutic response to neoadjuvant therapy for locoregionally advanced rectal cancer: a systematic review

Introduction: The standard of care for locoregionally advanced rectal cancer is neoadjuvant therapy (NA CRT) prior to surgery, of which 10-30% experience a complete pathologic response (pCR). There has been interest in using imaging features, also known as radiomics features, to predict pCR and potentially avoid surgery. This systematic review aims to describe the spectrum of MRI studies examining high-performing radiomic features that predict NA CRT response.Areas covered: This article reviews the use of pre-therapy MRI in predicting NA CRT response for patients with locoregionally advanced rectal cancer (T3/T4 and/or N1+). The primary outcome was to identify MRI radiomic studies; secondary outcomes included the power and the frequency of use of radiomic features.Expert opinion: Advanced models incorporating multiple radiomics categories appear to be the most promising. However, there is a need for standardization across studies with regards to; the definition of NA CRT response, imaging protocols, and radiomics features incorporated. Further studies are needed to validate current radiomics models and to fully ascertain the value of MRI radiomics in the response prediction for locoregionally advanced rectal cancer.

How to measure tumour response in rectal cancer? An explanation of discrepancies and suggestions for improvement

Various methods categorize tumour response after neoadjuvant therapy, including down-staging and tumour regression grading. Response categories allow comparison of different treatments within clinical trials and predict outcome. A reproducible response categorization could identify subgroups with high or low risk for the most appropriate subsequent treatments, like watch and wait. Lack of standardization and interpretation difficulties currently limit the usability of these approaches. In this review we describe these difficulties for the evaluation of chemoradiation in rectal cancer. An alternative approach of tumour response is based on patterns of residual disease, including fragmentation. We summarise the evidence behind this alternative method of response categorisation, which explains a number of very relevant clinical discrepancies. These issues include differences between downstaging and tumour regression, high local regrowth in advanced tumours during watchful waiting procedures, the importance of resection margins, the limited value of post-treatment biopsies and the relatively poor outcome of patients with a near complete pathological response. Recognition of these patterns of response can allow meaningful development of novel biomarkers in the future.

Pathological Tumor Regression Grade Classifications in Gastrointestinal Cancers: Role on Patients' Prognosis

Preoperative chemotherapy or combined radiotherapy and chemotherapy (CRT), followed by surgery, represents the standard approach for locally advanced esophageal, gastric, and rectal carcinomas. To adequately evaluate the effects of neoadjuvant CRT in the resection specimens, several histopathologic tumor regression grade (TRG) scoring systems have been introduced into clinical practice. The primary goal of these TRG systems relies on a correct prognostic stratification of patients in the attempt to help clinical decision-making and influence surgical strategies, postoperative adjuvant therapies, and surveillance intensity. However, most TRG systems suffer from poor reproducibility and low interobserver concordance rates. Many efforts have been made in the identification of alternative, robust, simple, and universally accepted TRG scoring systems, which would help in the comparison of different treatment strategies and in the standardization of multimodal therapies. The aim of this review is to analyze the most commonly used TRG systems in gastrointestinal cancers highlighting their pitfalls and usefulness, depending on the tumor type.

Magnetic resonance imaging in locally advanced rectal cancer: quantitative evaluation of the complete response to neoadjuvant therapy

Purpose

To assess the diagnostic performance of diffusion-weighted imaging (DWI) for the discrimination of complete responder (CR) from the non-complete responder (n-CR) in patients with locally advanced rectal cancer (LARC) undergoing chemotherapy and radiation (CRT).

Material and methods

Between December 2009 and January 2014, 32 patients (33 lesions: one patient had two synchronous lesions) were enrolled in this retrospective study. All patients underwent a pre- and post-CRT conventional MRI study completed with DWI. For both data sets (T2-weighted and DWI), the pre- and post-CRT tumour volume (V_T2; V_DWI) and the tumour volume reduction ratio (ΔV%) were determined as well as pre- and post-CRT apparent diffusion coefficient (ADC) and ADC change (ΔADC%). Histopathological findings were the standard of reference. Receiver operating characteristic (ROC) curves were generated to compare performance of T2-weighted and DWI volumetry, as well as ADC.

Results

The area under the ROC curve (AUC) revealed a good accuracy of pre- and post-CRT values of V_T2 (0.86; 0.91) and V_DWI (0.82; 1.00) as well as those of ΔV_T2% (0.84) and ΔV_DWI% (1.00) for the CR assessment, with no statistical difference. The AUC of pre- and post-CRT ADC (0.53; 0.54) and that of ΔADC% (0.58) were significantly lower.

Conclusions

Both post-CRT V_DWI and ΔV_DWI% (AUC = 1) are very accurate for the assessment of the CR, in spite of no significant differences in comparison to the conventional post-CRT V_T2 (AUC = 0.91) and ΔV_T2% (AUC = 0.84). On the contrary, both ADC and ΔADC% values are not reliable.

MR Imaging with Apparent Diffusion Coefficient Histogram Analysis: Evaluation of Locally Advanced Rectal Cancer after Chemotherapy and Radiation Therapy

Purpose To determine response to neoadjuvant chemotherapy and radiation therapy in patients with locally advanced rectal cancer (LARC) by using magnetic resonance (MR) apparent diffusion coefficient (ADC) histogram analysis. Materials and Methods Ninety-two patients with LARC underwent MR imaging with rectal barium before and after chemotherapy and radiation therapy (CRT). Rectal expansion with barium expanded the lumen, provided similar imaging geometry before and after CRT, and eliminated fecal matter, air, and residual fluid. T2-weighted images, the percentage change in ADC, and ADC histogram skewness and kurtosis were assessed. The histopathologic tumor regression grade (TRG) ranged from 1a (66%-99% residual tumor cells) to 3 (no residual cells). The Wilcoxon signed-rank test, the Spearman correlation test, multivariable linear regression, and one-way analysis of variance were used to determine post- and pretreatment differences and correlations between tumor size and ADC. Results Of the 92 patients, 16 (17.4%) had TRG 3, 27 (29.3%) had TRG 2b, 24 (26.1%) had TRG 2a, 14 (15.2%) had TRG 1b, and 11 (12%) had TRG 1a. Post-CRT skewness (regression coefficient = 10.9, P = .06) and percentage ADC change (regression coefficient = -0.18, P = .03) were associated with the percentage of residual tumor. Post-CRT skewness and percentage ADC change, respectively, showed negative and positive correlation with histopathologic TRG (post-CRT skewness: P = .024; percentage ADC change: P = .001). Conclusion In patients with LARC, post-CRT skewness of the ADC histogram and percentage change in ADC were useful for predicting a favorable response to neoadjuvant CRT. ^© RSNA, 2018 Online supplemental material is available for this article.

Importance of the Circumferential Extent of Tumors and Clinical Lymph Node Status as Prognostic Factors after Preoperative Chemoradiotherapy and Surgery in Patients with Rectal Cancer

Aims and background

To evaluate the clinical factors that influence pathological and clinical outcomes after preoperative concurrent chemoradiotherapy in patients with rectal cancer.

Methods

Between 1999 and 2004, 121 patients with cT3-4 or node-positive rectal cancer received preoperative chemoradiotherapy and surgery. Preoperative radiation therapy with 45 Gy was delivered. Fluorouracil-based chemotherapy was administered to most of the patients.

Results

Pathological complete remission was 14.3% after preoperative chemoradiotherapy. More than 60% tumor circumferential extent was an independent adverse factor for complete remission (P = 0.011, HR 4.643, 95% CI 1.415–15.231). Local recurrence developed in 9.9% of the cases. Serum CEA level ≥5 ng/ml (P = 0.057, HR 3.022, 95% CI 0.967–9.441) and >60% circumferential extent of tumor (P = 0.064, HR 4.232, 95% CI 0.918–19.531) were marginal adverse factors for local recurrence. Five-year disease-free survival and overall survival were 72.2% and 86.6%, respectively. Disease-free survival was poor for patients with the lymph nodes ≥1 cm in diameter (P = 0.028), cN2 stage disease (P = 0.047) and >60% circumferential extent of tumor (P = 0.058). Multivariate analysis for disease-free survival showed that the lymph node size ≥1 cm was an adverse factor (P = 0.019, HR 2.380, 95% CI 1.115–4.906). Patients with >60% circumferential extent of tumor and cN2 stage had a more unfavorable survival than the other patients (disease-free survival, P = 0.018; overall survival, P = 0.015). Patients with >60% circumferential extent of tumor and/or lymph node ≥1 cm also had an unfavorable survival (disease-free survival, P = 0.016; overall survival, P = 0.049).

Conclusions

In rectal cancer, circumferential extent of tumor and clinical lymph node status were important factors for preoperative chemoradiotherapy and surgery. A further prospective study is needed to confirm and expand these findings.

Tumor Volume Reduction Assessed by Planning Computed Tomography in Patients with Rectal Cancer during Preoperative Chemoradiation: Impact of Residual Tumor Volume on the Prediction of Pathologic Tumor Regression

Aims and Background

To determine whether the residual tumor volume measured using the Eclipse treatment planning system correlates with pathologic tumor regression grade after preoperative chemoradiotherpy for rectal cancer.

Materials and Methods

The study included 30 patients with rectal cancer who had undergone preoperative chemoradiotherpy followed by surgery from June 2008 to April 2011 at the Korea University Guro Hospital. The tumor volume was measured using the Eclipse treatment planning system in the initial simulation computed tomography and boost planning computed tomography. The correlation between the residual tumor volume in boost planning computed tomography and the pathologic tumor regression grade was analyzed. Tumor regression grade defined in the American Joint Committee on Cancer 7th edition was used.

Results

The mean and median residual tumor volume was 57.34% ± 20.37% and 52.35% (range, 18.42%-95.79%), respectively. After surgery, pathologic complete response (tumor regression grade 0) occurred in 4 patients (13.33%), moderate response (tumor regression grade 1) in 18 patients (60%), minimal response (tumor regression grade 2) in 4 patients (13.33%), and poor response (tumor regression grade 3) in 4 patients (13.33%). When residual tumor volume was categorized into two groups (<50% and ≥50%), complete or moderate regression (tumor regression grade 0 or 1) was significantly greater for patients with a residual tumor volume <50% (P <0.05). The mean residual tumor volume of tumor regression grade 0 or 1 was 49.07% ± 18.39% and that of tumor regression grade 2 or 3 was 76.31% ± 16.94% (P <0.05).

Conclusions

Residual tumor volume measured using routine boost planning computed tomography during preoperative chemoradiotherpy correlated significantly with pathologic tumor regression grade after surgery.

Intravoxel incoherent motion diffusion-weighted imaging for discriminating the pathological response to neoadjuvant chemoradiotherapy in locally advanced rectal cancer

To investigate the usefulness of intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) in discriminating the pathological complete response (pCR) to neoadjuvant chemoradiotherapy (nCRT) in locally advanced rectal cancer (LARC), 42 patients underwent preoperative IVIM-DWI before (pre-nCRT) and after nCRT (post-nCRT). The values of pre-nCRT and post-nCRT IVIM-DWI parameters (ADC, D, D* and f), together with the percentage changes (∆% parametric value) induced by nCRT, were compared between the pCR (tumour regression grade [TRG] 4) and non-pCR (TRG 0, 1, 2 or 3) groups and between the GR (TRG 3 or 4) and PR (TRG 0, 1 or 2) groups based on the Dworak TRG system. After nCRT, the ADC and D values for LARC increased significantly (all P < 0.05). The TRG score revealed a positive correlation with pref (r = 0.357, P = 0.020), postD (r = 0.551, P < 0.001) and Δ%D (r = 0.605, P < 0.001). The pCR group (n = 10) had higher preD*, pref, postD, ∆%ADC and ∆%D values than the non-pCR group (n = 32) (all P < 0.05). The GR group (n = 15) exhibited higher postD, ∆%ADC and ∆%D values than the PR group (n = 27) (all P < 0.05). Based on ROC analysis, ∆%D had a higher area under the curve value than ∆%ADC (P = 0.009) in discriminating the pCR from non-pCR groups. In conclusion, IVIM-DWI may be helpful in identifying the pCR to nCRT for LARC and is more accurate than traditional DWI.

Value of diffusion-weighted MRI and apparent diffusion coefficient measurements for predicting the response of locally advanced rectal cancer to neoadjuvant chemoradiotherapy

PURPOSE

The aim of our study was to assess the performance value of magnetic resonance imaging (MRI) in the restaging of locally advanced rectal cancer after neoadjuvant chemoradiotherapy (CRT) and in the identification of good vs. poor responders to neoadjuvant therapy.

MATERIALS AND METHODS

A total of 34 patients with locally advanced rectal cancer underwent MRI prior to and after CRT. T stage and tumor regression grade (TRG) on post-CRT MRI was compared with the pathological staging ypT and TRG. Tumor volume and the apparent diffusion coefficient (ADC) were measured using diffusion-weighted imaging (DWI) before and after neoadjuvant CRT; the percentage of tumor volume reduction and the change of ADC (ΔADC) was also calculated. ADC parameters and the percentage of tumor volume reduction were correlated to histopathological results. The diagnostic performance of ADC and volume reduction to assess tumor response was evaluated by calculating the area under the ROC curve and the optimal cut-off values.

RESULTS

A significant correlation between the T stage and the TRG defined in DW-MRI after CRT and the ypT and the TRG observed on the surgical specimens was found (p = 0.001; p < 0.001). The mean post-CRT ADC and ΔADC in responder patients was significantly higher compared to non-responder ones (p = 0.001; p = 0.01). Furthermore, the mean post-CRT ADC values were significantly higher in tumors with T-downstage (p = 0.01).

CONCLUSION

DW-MRI may have a significant role in the restaging and in the evaluation of post-CRT response of locally advanced rectal cancer. Quantitative analysis of DWI through ADC map may result in a promising noninvasive tool to evaluate the response to therapy.

Pathologic Assessment of Rectal Carcinoma after Neoadjuvant Radio(chemo)therapy: Prognostic Implications

Neoadjuvant radio(chemo)therapy is increasingly used in rectal cancer and induces a number of morphologic changes that affect prognostication after curative surgery, thereby creating new challenges for surgical pathologists, particularly in evaluating morphologic changes and tumour response to preoperative treatment. Surgical pathologists play an important role in determining the many facets of rectal carcinoma patient care after neoadjuvant treatment. These range from proper handling of macroscopic specimens to accurate microscopic evaluation of pathological features associated with patients' prognosis. This review presents the well-established pathological prognostic indicators and discusses challenging features in order to provide both surgical pathologists and treating physicians with a checklist that is useful in a neoadjuvant setting.

Assessing pathological complete response to neoadjuvant chemoradiotherapy in locally advanced rectal cancer: a systematic review

AIM

Pathological complete response to neoadjuvant chemoradiotherapy is found in 20% of patients with rectal cancer undergoing long-course chemoradiotherapy. Some authors have suggested that these patients do not need to undergo surgery and can be managed with careful follow-up, with surgery only used in the event of clinical failure. Widespread adoption of this regimen is limited by the accuracy of methods to confirm a pathological complete response (pCR).

METHOD

A systematic search of PubMed, Medline and Cochrane databases was conducted to identify clinical, histological and radiological features in those patients with rectal cancer who achieved a pCR following chemoradiotherapy. Searches were conducted with the following keywords and MeSH search terms: 'rectal neoplasm', 'response', 'neoadjuvant', 'preoperative chemoradiation' and 'tumour response'. After review of title and abstracts, 89 articles addressing the assessment of pCR were identified.

RESULTS

Histology and clinical assessment are the most effective methods of assessment of pCR, with histology considered the gold standard. Clinical assessment is limited to low rectal tumours and is open to significant inter-rater variability, while histological examination requires a surgical specimen. Diffusion-weighted MRI and (18) F-fluorodeoxyglucose positron emission tomography/CT demonstrate the greatest potential for the assessment of pCR, but both modalities have limited accuracy.

CONCLUSION

Determination of a pCR is crucial if a nonoperative approach is to be undertaken proactively. Various methods are available, but currently they lack sufficient sensitivity and specificity to define management. This is likely to be an area of further research in the future.

Systematic review and meta-analysis of the accuracy of MRI and endorectal ultrasound in the restaging and response assessment of rectal cancer following neoadjuvant therapy

AIM

Restaging imaging by MRI or endorectal ultrasound (ERUS) following neoadjuvant chemoradiotherapy is not routinely performed, but the assessment of response is becoming increasingly important to facilitate individualization of management.

METHOD

A search of the MEDLINE and Scopus databases was performed for studies that evaluated the accuracy of restaging of rectal cancer following neoadjuvant chemoradiotherapy with MRI or ERUS against the histopathological outcome. A systematic review of selected studies was performed. The methodological quality of studies that qualified for meta-analysis was critically assessed to identify studies suitable for inclusion in the meta-analysis.

RESULTS

Sixty-three articles were included in the systematic review. Twelve restaging MRI studies and 18 restaging ERUS studies were eligible for meta-analysis of T-stage restaging accuracy. Overall, ERUS T-stage restaging accuracy (mean [95% CI]: 65% [56-72%]) was nonsignificantly higher than MRI T-stage accuracy (52% [44-59%]). Restaging MRI is accurate at excluding circumferential resection margin involvement. Restaging MRI and ERUS were equivalent for prediction of nodal status: the accuracy of both investigations was 72% with over-staging and under-staging occurring in 10-15%.

CONCLUSION

The heterogeneity amongst restaging studies is high, limiting conclusive findings regarding their accuracies. The accuracy of restaging imaging is different for different pathological T stages and highest for T3 tumours. Morphological assessment of T- or N-stage by MRI or ERUS is currently not accurate or consistent enough for clinical application. Restaging MRI appears to have a role in excluding circumferential resection margin involvement.

MRI tumor volume reduction rate vs tumor regression grade in the pre-operative re-staging of locally advanced rectal cancer after chemo-radiotherapy

OBJECTIVE

To compare tumor volume reduction rate (TVRR) measured by MR volumetry after preoperative chemoradiotherapy (CRT) and pathological tumor regression grade (TRG) in locally advanced rectal cancer (LARC).

MATERIAL AND METHODS

In total, 20 patients with LARC (cT3-T4) treated with CRT followed by Total Mesorectal Excision (TME) between April 2011 and April 2013 were analyzed retrospectively. Pre- and post- CRT tumor volumes (MR volumetry) were measured on 3D MR sequences. TVRR was determined using the equation TVRR (%)=(pre-CRT tumor volume-post-CRT tumor volume)×100/pre-CRT tumor volume. The downstaging (defined as ypT0-T2) of tumor mass was evaluated and the correlation between TVRR and TRG was calculated with the method proposed by Dworak using the Spearman rank test.

RESULTS

The median TVRR was 77.3% (range, 26.4-99.3%); TVRR was >60% in 18 cases (90%) and in 8 of these patients (44.4 %) it was >80%. Downstaging of tumor lesions was obtained in 15 patients (75%). In 4 cases there was a complete tumor regression (TRG4) at histological examination and in the same patients there was also a TVRR>80% measured by MR volumetry. A statistically significant correlation between TVRR and TRG (r(s)=0.5466, p=0.0126) was observed.

CONCLUSION

TVRR after preoperative CRT correlates with TRG in LARC. The MR volumetry is a prognostic factor to estimate the tumor response after preoperative CRT. TVRR data may be an useful biomarker for tailoring surgery and postoperative adjuvant chemotherapy.

Tumor Volume Reduction Rate Predicts Pathologic Tumor Response of Locally Advanced Rectal Cancer Treated with Neoadjuvant Chemotherapy alone: Results from a Prospective Trial

Purpose: To evaluate tumor volume reduction rate (TVRR) measured by three-dimensional region-of-interest (3D-ROI) magnetic resonance (MR) volumetry in predicting pathological tumor response of preoperative chemotherapy alone for locally advanced rectal cancer (LARC).

Methods: LARC patients who received neoadjuvant chemotherapy only from a prospective and randomized trial were recruited. Tumor volumes were measured with 3D-ROI MR volumetry. TVRR was determined using the equation TVRR = (V_Pre-Therapy - V_{Post-Therapy)} / V_Pre-Therapy ×100%. Correlation between TVRR and clinical or pathological characteristics and predictive value of TVRR for pathological tumor response in terms of Tumor Regression Grade (TRG), T downstage, N downstage and overall downstage were analyzed.

Results: 80 eligible cases of LARC were included in our study with TVRR of (51.7±25.1) %. TVRR was higher in well-differentiated tumors compared with poor-differentiated tumors (P=0.040). TVRR was found to be related with TRG (P<0.001), T downstage (P<0.001) and overall downstage (P<0.001). Risk of achieving TRG 2/3 decreased to 57.5% (P=0.002) and odds of achieving overall downstage increase to 179.3% (P<0.001) when TVRR increased by every 10%. A sensitivity of 0.704 and specificity of 0.804 were calculated when ROC curve was constructed to predict TRG using TVRR with a cutoff of 65%.

Conclusion: TVRR is correlated with TRG and overall downstage significantly in LARC patients treated with preoperative chemotherapy alone and shows great value in predicting favorable TRG and overall downstage with good sensitivity and specificity. It could be considered as a promising parameter candidate for efficacy evaluation.

Endoscopic evaluation of clinical response after preoperative chemoradiotherapy for lower rectal cancer: the significance of endoscopic complete response

PURPOSE

The management of rectal cancer is a significant oncologic challenge because rectal cancer has a poor prognosis among the various types of colorectal cancer. There have been several recent reports on a nonoperative approach for advanced lower rectal cancer, and this may be best for local disease control. However, objective evaluation of tumor response after preoperative chemoradiotherapy has not been standardized. The purpose of this study is to evaluate our method of endoscopic evaluation of complete response.

METHODS

This is a retrospective chart review. All patients received a long course of preoperative chemoradiotherapy (5-fluorouracil-based chemotherapy and 45-50.4 Gy) followed by radical surgical resection from May 2005 to March 2012 in The Cancer Institute Hospital of Japanese Foundation for Cancer Research. One hundred fifty-seven patients were reviewed consecutively. Criteria for endoscopic complete response were defined with a focus on the degree of ulcer healing and pit pattern without magnification.

RESULTS

Endoscopic CR (E-CR) evaluation with our definitions reflected histopathologic response evaluation with an accuracy of 91.7 %, sensitivity of 27.8 %, specificity of 100 %, positive predictive value (PPV) of 100 %, and negative predictive value (NPV) of 91.4 % (p < 0.001). Our criteria of E-CR led all cases of y-clinical CR (ycCR) to pathological CR.

CONCLUSIONS

Endoscopic evaluation focused on the degree of ulcer healing, and pit pattern without magnification is useful for judging ycCR.

Effects of Preoperative Chemoradiotherapy on the Likelihood of Sphincter Preservation Surgery in Locally Advanced Distal Rectal Cancer: A Longitudinal Study Based on Pelvic Magnetic Resonance Imaging

BACKGROUND

It is unclear whether preoperative chemoradiotherapy (pCRT) increases the rate of sphincter-preserving surgery (SPS), avoiding abdominoperineal resection (APR), for the treatment of distal rectal cancer. We examined whether pCRT increases the likelihood of SPS based on changes in tumor height using pelvic magnetic resonance imaging (MRI).

METHODS

Between January 2009 and December 2013, 105 patients underwent long-course pCRT for locally advanced distal rectal cancer (≤5 cm from the anal verge) and were included in this study. The surgical procedures were analyzed in terms of radiologic findings, including the distance from the inferior margin of tumor to the superior margin of the anorectal ring (tumor height) measured by pelvic MRI before and after pCRT.

RESULTS

Eighty-six (81.9 %) patients underwent SPS. Overall clinical downstaging occurred in 48 (45.7 %) patients. Tumor height increased significantly after pCRT (from 15.0 ± 15.3 to 18.1 ± 16.9 mm, change 3.1 ± 9.7 mm, p = 0.01). The mean change in tumor height was not significantly different between patients who underwent SPS or APR (mean change 3.3 ± 9.6 vs. 2.3 ± 10.5 mm, p = 0.68). The mean change was significantly greater in the double-stapled anastomosis group than in the handsewn anastomosis group (mean change 5.6 ± 9.9 vs. -0.6 ± 8.6 mm, p = 0.02).

CONCLUSIONS

This was the first MRI-based longitudinal study to show that pCRT does not appear to increase the likelihood of SPS in locally advanced distal rectal cancer, although it could improve the potential of double-stapled anastomoses.

Abdominoperineal excision following preoperative radiotherapy for rectal cancer: Unfavorable prognosis even with negative circumferential resection margin

AIM: To evaluate whether an abdominoperineal excision (APE) is associated with increased local recurrence (LR) and shortened disease-free survival (DFS) in mid-low rectal cancer with a negative circumferential resection margin (CRM).

METHODS: 283 consecutive cases of mid-low rectal cancer underwent preoperative 30 Gy/10 F radiotherapy and surgery in Peking University Cancer Hospital between August 2003 and August 2009. Patients with positive CRM and intraoperative distant metastasis were precluded according to exclusion criteria. Survival analyses were performed in patients with APE or non-APE procedures.

RESULTS: 256 of the 283 (90.5%) cases were enrolled in the analysis, including 78 (30.5%) and 178 (69.5%) cases who received APE and non-APE procedures. Fewer female patients (P = 0.016), lower level of tumor (P = 0.000) and higher body mass index (P = 0.006) were found in the APE group. On univariate analysis, the APE group had a higher LR rate (5.1% vs 1.1%, P = 0.036) and decreased DFS (73.1% vs 83.4%, P = 0.021). On multivariate analysis, APE procedure was also an independent risk factor for LR (HR = 5.960, 1.085-32.728, P = 0.040) and decreased DFS (HR = 2.304, 1.298-4.092, P = 0.004). In stratified analysis for lower rectal cancer, APE procedure was still an independent risk factor for higher LR rate (5.6% vs 0%, P = 0.024) and shortened DFS (91.5% vs 73.6%, P = 0.002).

CONCLUSION: Following preoperative 30 Gy/10 F radiotherapy, APE procedure was still a predictor for LR and decreased DFS even with negative CRM. More intensive preoperative treatment should be planned for the candidates who are scheduled to receive APE with optimal imaging assessment.

Current approaches and challenges for monitoring treatment response in colon and rectal cancer

Introduction: With the advent of multidisciplinary and multimodality approaches to the management of colorectal cancer patients, there is an increasing need to define how we monitor response to novel therapies in these patients. Several factors ranging from the type of therapy used to the intrinsic biology of the tumor play a role in tumor response. All of these can aid in determining the ideal course of treatment, and may fluctuate over time, pending down-staging or progression of disease. Therefore, monitoring how disease responds to therapy requires standardization in order to ultimately optimize patient outcomes. Unfortunately, how best to do this remains a topic of debate among oncologists, pathologists, and colorectal surgeons. There may not be one single best approach. The goal of the present article is to shed some light on current approaches and challenges to monitoring treatment response for colorectal cancer.

Methods: A literature search was conducted utilizing PubMed and the OVID library. Key-word combinations included colorectal cancer metastases, neoadjuvant therapy, rectal cancer, imaging modalities, CEA, down-staging, tumor response, and biomarkers. Directed searches of the embedded references from the primary articles were also performed in selected circumstances.

Results: Pathologic examination of the post-treatment surgical specimen is the gold standard for monitoring response to therapy. Endoscopy is useful for evaluating local recurrence, but not in assessing tumor response outside of the limited information gained by direct examination of intra-lumenal lesions. Imaging is used to monitor tumors throughout the body for response, with CT, PET, and MRI employed in different circumstances. Overall, each has been validated in the monitoring of patients with colorectal cancer and residual tumors.

Conclusion: Although there is no imaging or serum test to precisely correlate with a tumor's response to chemo- or radiation therapy, these modalities, when used in combination, can aid in allowing clinicians to adjust medical therapy, pursue operative intervention, or (in select cases) identify complete responders. Improvements are needed, however, as advances across multiple modalities could allow appropriate selection of patients for a close surveillance regimen in the absence of operative intervention.

The role of perfusion effects in monitoring of chemoradiotherapy of rectal carcinoma using diffusion-weighted imaging

PURPOSE

The aim of this study was to characterize and understand the therapy-induced changes in diffusion parameters in rectal carcinoma under chemoradiotherapy (CRT). The current literature shows conflicting results in this regard. We applied the intravoxel incoherent motion model, which allows for the differentiation between diffusion (D) and perfusion (f) effects, to further elucidate potential underlying causes for these divergent reports.

MATERIALS AND METHODS

Eighteen patients with primary rectal carcinoma undergoing preoperative CRT were examined before, during, and after neoadjuvant CRT using diffusion-weighted imaging. Using the intravoxel incoherent motion approach, f and D were extracted and compared with postoperative tumor downstaging and volume.

RESULTS

Initial diffusion-derived parameters were within a narrow range (D1 = 0.94 ± 0.12 × 10(-3) mm(2)/s). At follow-up, D rose significantly (D2 = 1.18 ± 0.13 × 10(-3) mm(2)/s; P < 0.0001) and continued to increase significantly after CRT (D3 = 1.24 ± 0.14 × 10(-3) mm(2)/s; P < 0.0001). The perfusion fraction f did not change significantly (f1 = 9.4 ± 2.0%, f2 = 9.4 ± 1.7%, f3 = 9.5 ± 2.7%). Mean volume (V) decreased significantly (V1 = 16,992 ± 13,083 mm(3); V2 = 12,793 ± 8317 mm(3), V3 = 9718 ± 6154 mm(3)). T-downstaging (10:18 patients) showed no significant correlation with diffusion-derived parameters.

CONCLUSIONS

Conflicting results in the literature considering apparent diffusion coefficient (ADC) changes in rectal carcinoma under CRT for patients showing T-downstaging are unlikely to be due to perfusion effects. Our data support the view that under effective therapy, an increase in D/ADC can be observed.

Clinical utility of integrated positron emission tomography/computed tomography imaging in the clinical management and radiation treatment planning of locally advanced rectal cancer

PURPOSE

The role of 18F-fluorodeoxyglucose positron emission tomography-computed tomography (FDG-PET/CT) in the staging and radiation treatment planning of locally advanced rectal cancer is ill defined. We studied the role of integrated PET/CT in the staging, radiation treatment planning, and use as an imaging biomarker in rectal cancer patients undergoing multimodality treatment.

METHODS AND MATERIALS

Thirty-four consecutive patients with T3-4N0-2M0-1 rectal adenocarcinoma underwent FDG-PET/CT scanning for staging and radiation treatment planning. Planned clinical management was compared before and after the addition of PET/CT information. Three radiation oncologists independently delineated CT-based gross tumor volumes (GTVCT) using clinical information and CT imaging data, as well as gradient autosegmented PET/CT-based GTVs (GTVPETCT). The mean GTV, interobserver concordance index (CCI), and proximal and distal margins were compared. The maximal standardized uptake value (SUVmax), metabolic tumor volume (MTV), and dual-time point PET parameters were correlated with clinicopathologic endpoints.

RESULTS

Clinical management was altered by PET/CT in 18% (n = 6) of patients with clinical upstaging in 6 patients and radiation treatment planning altered in 5 patients. Of the 30 evaluable preoperative patients, the mean GTVPETCT was significantly smaller than the mean GTVCT volumes: 88.1 versus 102.8 cc (P = .03). PET/CT significantly increased interobserver CCI in contouring GTV compared with CT only-based contouring: 0.56 versus 0.38 (P < .001). The proximal and distal margins were altered by a mean of 0.4 ± 0.24 cm and -0.25 ± 0.18 cm, respectively. MTV was inversely associated with 2-year progression-free survival (PFS) and overall survival (OS): smaller MTVs (<33 cc) had superior 2-year PFS (86% vs 60%, P = .04) and OS (100% vs 45%, P < .01) compared with larger MTVs (>33 cc). SUVmax and dual-time point PET parameters did not correlate with any endpoints.

CONCLUSIONS

FDG-PET/CT imaging impacts overall clinical management and is useful in the radiation treatment planning of rectal cancer patients by decreasing interobserver variability in contouring target boost volumes. Pretreatment MTV may provide useful prognostic information and requires further study.

Diffusion-weighted magnetic resonance for prediction of response after neoadjuvant chemoradiation therapy for locally advanced rectal cancer: preliminary results of a monoinstitutional prospective study

PURPOSE

To evaluate diffusion-weighted imaging (DWI) for assessment of treatment response in locally advanced rectal cancer (LARC) 8 weeks after neoadjuvant chemoradiotherapy (CRT).

METHODS AND MATERIALS

A total of 28 patients with LARC underwent magnetic resonance imaging (MRI) prior to and 8 weeks after CRT. Tumor volume (TV) was calculated on T2-weighted MRI scans as well as the apparent diffusion coefficient (ADC) was calculated using Echo-planar DWI-sequences. All data were correlated to surgical results and histopathologic tumor regression grade (TRG), according to Mandard's classification. Post-treatment difference ADC (%ΔADC) and TV (%ΔTV) changes at 8 weeks were compared complete response (CR; TRG1) and non-complete response tumors (non-CR; TRG2-5).

RESULTS

The mean % ADC increase of CR group was significantly higher compared to non-CR group (77.2 ± 54.63% vs. 36.0 ± 29.44%; p = 0.05). Conversely, the mean % TV reduction did not significantly differ in CR group from non-CR group (73.7% vs. 63.77%; p = 0.21). Accordingly, the diagnostic accuracy of the mean % ADC increase to discriminate CR from non-CR group was significantly higher than that of the mean % TV reduction (0.913 vs. 0.658; p = 0.022). No correlation was found between mean % TV reduction and TRG (rho = 0.22; p = 0.3037), whereas a negative correlation between mean % ADC increase and TRG was recorded (r = -0.69; p = 0.006).

CONCLUSION

The mean % ADC increase appears to be a reliable tool to differentiate CR from non-CR after CRT in patients with LARC.

Locally advanced rectal cancer: diffusion-weighted MR tumour volumetry and the apparent diffusion coefficient for evaluating complete remission after preoperative chemoradiation therapy

OBJECTIVE

To evaluate DW MR tumour volumetry and post-CRT ADC in rectal cancer as predicting factors of CR using high b values to eliminate perfusion effects.

METHODS

One hundred rectal cancer patients who underwent 1.5-T rectal MR and DW imaging using three b factors (0, 150, and 1,000 s/mm(2)) were enrolled. The tumour volumes of T2-weighted MR and DW images and pre- and post-CRT ADC150-1000 were measured. The diagnostic accuracy of post-CRT ADC, T2-weighted MR, and DW tumour volumetry was compared using ROC analysis.

RESULTS

DW MR tumour volumetry was superior to T2-weighted MR volumetry comparing the CR and non-CR groups (P < 0.001). Post-CRT ADC showed a significant difference between the CR and non-CR groups (P = 0.001). The accuracy of DW tumour volumetry (Az = 0.910) was superior to that of T2-weighed MR tumour volumetry (Az = 0.792) and post-CRT ADC (Az = 0.705) in determining CR (P = 0.015). Using a cutoff value for the tumour volume reduction rate of more than 86.8 % on DW MR images, the sensitivity and specificity for predicting CR were 91.4 % and 80 %, respectively.

CONCLUSION

DW MR tumour volumetry after CRT showed significant superiority in predicting CR compared with T2-weighted MR images and post-CRT ADC.

Intermediate-fraction neoadjuvant radiotherapy for rectal cancer

BACKGROUND

In China, standard neoadjuvant chemoradiation therapy has not been well accepted, not only because of financial constraints but also because of the poorly-tolerated long duration of the regimen.

OBJECTIVE

The current study aimed to evaluate the impact of a modified neoadjuvant radiation regimen on the prognosis of rectal cancer patients in China.

DESIGN

This was a nonrandomized cohort study evaluating outcomes of patients who chose to undergo preoperative radiotherapy compared with those who chose not to undergo preoperative radiotherapy (controls).

SETTINGS

The study was carried out in Peking University Cancer Hospital, a tertiary care cancer center in China.

PATIENTS

Records of patients with locally advanced, mid-to-low rectal cancer who underwent total mesorectal excision at Peking University Cancer Hospital from 2001 through 2005 were analyzed in this study.

INTERVENTION

Patients who chose preoperative radiotherapy received a total dose of 30 Gy delivered in 10 once-daily fractions of 3.0 Gy each, with at least a 14-day delay of surgery after delivery of the last fraction.

MAIN OUTCOME MEASURES

Tumor downstaging was evaluated. Local recurrence, distant metastases, and disease-free and overall survival were analyzed with the Kaplan-Meier method.

RESULTS

A total of 101 patients accepted and 162 patients declined the modified preoperative radiotherapy regimen. Of the 101 patients receiving preoperative radiotherapy, 5 (5%) had a complete response, and 50 (50%) achieved TNM downstaging. The local recurrence rate was 5% with preoperative radiotherapy and 18% in the control groups (p = 0.02). Within the preoperative radiotherapy group, 5-year disease-free survival and overall survival rates were significantly higher in patients with T-, N-, or TNM-downstaging than in patients without downstaging. Evaluation of literature reports indicated that clinical safety and effectiveness of the modified protocol are comparable to results of standard neoadjuvant procedures.

LIMITATIONS

The allocation to study groups was not randomized, and patient self-selection may have introduced bias, particularly because patients with greater financial means were more likely to choose to undergo the preoperative radiotherapy regimen.

CONCLUSIONS

Compared with surgery alone, this modified preoperative radiotherapy regimen is associated with significantly reduced local recurrence and complication rates, with improved survival in patients who show downstaging. The modified protocol offers a clinical outcome equivalent to standard preoperative radiotherapy regimens while offering an alternative for increasing the flexibility of preoperative radiation regimens in China.

Comparison between CT volume measurement and histopathological assessment of response to neoadjuvant therapy in rectal cancer

OBJECTIVES

The aim of this study was to compare volume measurements on computed tomography (CT) images with histopathological assessments of chemoradiotherapy (CRT)-induced tumor regression in locally advanced rectal cancer (RC).

METHODS

In 25 patients (13 males, 12 females; median age, 63 years; age range, 44-79 years) with locally advanced RC treated with preoperative CRT and surgery, two radiologists measured tumor volume on CT images before and after CRT. CT-based tumor volumetry and the modified response evaluation criteria in solid tumors (mRECISTs) were compared with T and N downstaging after CRT, and with the tumor regression grade (TRG).

RESULTS

Tumor volumes were significantly smaller on CT images after CRT. The tumors regressed in 52% (13/25), 36% (9/25) and 40% (10/25) of patients, based on T downstaging, TRG and mRECIST findings, respectively. In terms of T downstaging, the pre- and post-CRT tumor volumes of responders and non-responders to the treatment differed statistically, while their tumor volume reduction rates and volume reductions according to the 65% mRECIST threshold did not. In terms of N downstaging and TRG, the differences between the responders' and the non-responders' pre- and post-CRT tumor volumes, tumor volume reduction rates, and mRECIST thresholds were never statistically significant.

CONCLUSION

Measuring tumor size on CT images is of limited value in predicting the histopathological response to preoperative CRT in RC patients, so it may be unwise to select surgical treatment strategies based on CT volumetry.

Assessment of response to chemoradiation therapy in rectal cancer using MR volumetry based on diffusion-weighted data sets: a preliminary report

PURPOSE

This study evaluated the feasibility of magnetic resonance (MR) volumetry using a diffusion-weighted data set (V(DWI)) and compared it with conventional T2-weighted volumetry (V(C)) in patients affected by rectal cancer treated with chemoradiation therapy (CHRT).

MATERIALS AND METHODS

Fourteen patients with a biopsy diagnosis of rectal cancer underwent MR examination before and after CHRT. T2-weighted images were used to extrapolate V(C). A diffusion-weighted (DW) sequence was acquired [spin-echo diffusion-weighted echo-planar imaging (SE-DW-EPI)] with a b-value of 800 s/mm(2) and volume (V(DWI)) was calculated by semiautomatic segmentation of tumour hyperintensity. Two radiologists independently assessed volumes and analysed data in order to establish interobserver agreement and compare and correlate volumes to tumour regression grade (TRG), as evaluable at pathological examination of the surgical specimen.

RESULTS

Interobserver agreement was 0.977 [(95% confidence interval (CI) 0.954-0.989) and 0.956 (95% CI 0.905-0.980) for V(C) and V(DWI) and 0.964 (95% CI 0.896-0.988) and 0.271 (95% CI-0.267 to 0.686) between V(C) and V(DWI) before and after CHRT. The correlation between TRG and V(C) and V(DWI) was, respectively, rho = 0.597 (p<0.05) and r(2)=0.156 (p=0.162) and rho=0.847 (p<0.001).

CONCLUSIONS

V(DWI) seems to be a promising tool for assessing response to CHRT in rectal cancer. Further studies on large series of patients are needed to refine the technique and evaluate its potential predictive value.

MR volumetric measurement of low rectal cancer helps predict tumor response and outcome after combined chemotherapy and radiation therapy

PURPOSE

To retrospectively determine whether magnetic resonance (MR) volumetry of rectal cancer is a reproducible method for predicting disease-free survival (DFS) in patients with locally advanced low or midrectal tumors who undergo combined chemotherapy and radiation therapy (CRT) before total mesorectal excision.

MATERIALS AND METHODS

The institutional review board does not require approval for the use of patient data obtained for an observational retrospective study. Fifty-eight patients were included in the study; 42 patients had low-lying tumors. Two radiologists independently measured tumor volumes before and after CRT with use of semiautomated software. The radiologists were blinded to the clinical information for each patient. The tumor volume reduction ratio, circumferential resection margin, T stage, and occurrence of downstaging were compared with the histopathologic response and DFS. The threshold of tumor volume reduction for predicting DFS was assessed with receiver operating characteristic curve analysis. DFS was estimated with the Kaplan-Meier method and compared between groups with the log-rank test.

RESULTS

The interobserver correlation coefficient between the two radiologists was 0.87 (95% confidence interval [CI]: 0.76, 0.93) for pre-CRT volumetry and 0.81 (95% CI: 0.74, 0.90) for post-CRT volumetry. A tumor volume reduction of at least 70% was significantly associated with good histologic regression (tumor regression grade [TRG], 3 or 4) (P <.0001) compared with a volume reduction rate of less than 70%. DFS was studied in 51 patients. The mean follow-up of survivors at the time of analysis was 52 months ± 20 (standard deviation). Patients with a volume reduction ratio of at least 70% had a higher DFS (P <.0001). Tumor volume reduction was an independent prognostic parameter in multivariate analysis for DFS (P = .003; 95% CI: 0.01, 0.4).

CONCLUSION

The results demonstrate that volumetric measurements are reliable markers of rectal cancer prognosis, enabling the prediction of DFS and TRG. The cutoff of 70% is an easy parameter to use as a surrogate for clinical response to predict both TRG and outcome.

Comparison of different SUV-based methods for response prediction to neoadjuvant radiochemotherapy in locally advanced rectal cancer by FDG-PET and MRI

PURPOSE

The aim of this study was to compare different analysis methods of 2-deoxy-2-[(18)F]fluoro-D-glucose positron emission tomography (FDG-PET) and magnetic resonance imaging (MRI) data for prediction of histopathological response (HPR) to neoadjuvant radiochemotherapy (RCTx) in patients with advanced rectal cancer.

PROCEDURES

Twenty-eight patients of a previously published clinical trial underwent serial FDG-PET/computed tomography scans at baseline, 14 days after initiation, and after completion of RCTx. In addition, MRI was performed at baseline and after the end of therapy. Response prediction was correlated with different image analysis algorithms comprising pure metabolic parameters taking into account the FDG uptake, volume-based parameters measuring the lesion volume in either MRI or PET data, and integrated parameters combining metabolic and volumetric information. The established two-dimensional (2D) regions of interest (ROI; diameter 1.5 cm) served as standard of reference. Changes between the parameters at the defined time points were calculated and analyzed for their potential to predict HPR to RCTx using receiver operating characteristic (ROC) analysis. Additionally, the interobserver reliability of fixed-size algorithms was analyzed.

RESULTS

Histopathology classified eight of 28 patients as non-responders and 20 patients as responders to RCTx. ROC analysis of the standard 2D ROI technique revealed areas under the curve (AUCs) of 0.64 and 0.71 for the early and late time points. Corresponding AUCs for three-dimensional (3D) volume of interest technique resulted in AUCs of 0.75 for both early and late time points, respectively. Volumetric parameters showed AUCs ranging from 0.52 to 0.57 (early time points) and 0.46 to 0.76 (later time points), respectively. Corresponding AUCs for the integrated parameters were ranging between 0.70 and 0.73 (early time points) and 0.66 and 0.76 (late time points). Analysis of intra-class correlation coefficients (ICC) for three different readers resulted in the best intra-class correlation values for the changes of 3D standard uptake value (SUV(3D)), for both early (ICC = 0.96) and late (ICC = 0.96) time points, respectively.

CONCLUSIONS

Our study emphasizes that 3D-based approaches for assessing SUV values consistently belonged to the group of parameters with the highest AUC values for prediction of HPR to neoadjuvant RCTx in patients with rectal cancer. MRI was not a good predictor for therapy response; hence, the MRI information derived from combined anatomic and metabolic parameters showed unsatisfying results too.

Morphology and prognostic value of tumor budding in rectal cancer after neoadjuvant radiotherapy

Tumor budding is an acknowledged prognostic marker in colorectal cancer. This study was conducted to investigate the morphology and prognostic significance of budding in rectal cancer after neoadjuvant radiotherapy. Surgical specimens from 96 consecutive patients who underwent neoadjuvant radiotherapy and curative resection were retrieved to assess budding and other clinicopathologic factors. The morphology and prognostic significance of postirradiation tumor budding were closely associated with tumor regression grade. In the tumor regression grade 1 group, tumor budding presented as "false budding" and did not have a significant association with prognosis. In the tumor regression grade 2 and 3 groups, budding was observed surrounded by radiation-induced fibrosis and large populations of infiltrating inflammatory cells, and budding intensity was significantly associated with histologic differentiation, ypN stage, and lymphovascular invasion (P < .05). Moreover, the low-grade budding subgroup showed a significantly higher rate of 5-year disease-free survival than the high-grade budding subgroup (87.5% versus 55.6%, P < .0001). Multivariate analysis showed that pretreatment serum carcinoembyronic antigen, tumor regression grade, and tumor budding were the major independent factors affecting long-term disease-free survival. In conclusion, postirradiation budding has distinct morphology and prognostic significance in rectal cancer after neoadjuvant radiotherapy.

Extending the role of Transanal Endoscopic Microsurgery (TEM) in rectal cancer

Increasingly it is becoming clear that there is a role for local excision of early rectal cancer by Transanal Endoscopic Microsurgery (TEM) as part of an organ-preservation strategy. This role is based on careful preoperative assessment, thorough postoperative histopathological examination and standardized follow up, with recourse to completion or salvage radical surgery in the face of poor prognostic factors, or early concerns over recurrent disease. Additionally, TEM is also proposed in selected circumstances after neoadjuvant treatment for rectal cancer. This latter topic is even more controversial with clinical evidence still evolving, but specialist centres report impressive results that cannot be ignored in the modern management of rectal cancer.

18Fluoro-deoxy-glucose positron emission tomography in assessing tumor response to preoperative chemoradiation therapy for locally advanced rectal cancer

BACKGROUND

This study aims to evaluate the efficacy of (18)F-FDG PET in assessing tumor response after preoperative chemoradiation therapy (CRT) for rectal cancer.

METHODS

Maximum standardized uptake value (SUV) was measured for 37 patients who underwent (18)F-FDG PET before and 4 weeks after completion of preoperative CRT. Pre-SUV, post-SUV, the difference between pre- and post-SUV (ΔSUV), and reduction rate (RR) were correlated with tumor response.

RESULTS

A lower mean post-SUV and a higher mean RR were shown in good tumor response (T-downstaging(+) and tumor regression grade 1, 2). Considering pathologic complete response (pCR), the mean post-SUV and the mean RR were significantly different between pCR (+) patients (N = 13) and pCR (-) patients (N = 24) (2.7 vs. 4.8, P < 0.001, 73.9% vs. 58.7%, P = 0.009). With a 3.35 cut-off value for the post-SUV by receiver operating characteristic analysis, 84.6% sensitivity, 79.2% specificity, and 81.2% overall accuracy were obtained for discriminating between pCR (+) and pCR (-) (area under the curve = 0.885, P < 0.001).

CONCLUSIONS

(18)F-FDG PET is potentially useful as a method for assessing tumor response after preoperative CRT for rectal cancer. Post-SUV and RR were significantly associated with pathological treatment response, especially in pCR.

High-dose-rate intraluminal brachytherapy during preoperative chemoradiation for locally advanced rectal cancers

AIM: To determine the feasibility and safety of high dose rate intraluminal brachytherapy (HDR-ILBT) boost during preoperative chemoradiation for rectal cancer.

METHODS: Between 2008 and 2009, thirty-six patients with locally advanced rectal cancer (≥ T3 or N+), were treated initially with concurrent capecitabine (825 mg/m² oral twice daily) and pelvic external beam radiotherapy (EBRT) (45 Gy in 25 fractions), then were randomized to group A; HDR-ILBT group (n = 17) to receive 5.5-7 Gy × 2 to gross tumor volume (GTV) and group B; EBRT group (n = 19) to receive 5.4 Gy × 3 fractions to GTV with EBRT. All patients underwent total mesorectal excision.

RESULTS: Grade 3 acute toxicities were registered in 12 patients (70.6%) in group A and in 8 (42.1%) in group B. Complete pathologic response of T stage (ypT0) in group A was registered in 10 patients (58.8%) and in group B, 3 patients (15.8%) had ypT0 (P < 0.0001). Sphincter preservation was reported in 6/9 patients (66.7%) in group A and in 5/10 patients (50%) in group B (P < 0.01). Overall radiological response was 68.15% and 66.04% in Group A and B, respectively. During a median follow up of 18 mo, late grade 1 and 2 sequelae were registered in 3 patients (17.6%) and 4 patients (21.1%) in the groups A and B, respectively.

CONCLUSION: HDR-ILBT was found to be effective dose escalation technique in preoperative chemoradiation for rectal cancers, with higher response rates, downstaging and with manageable acute toxicities.

Long-term outcome in patients with a pathological complete response after chemoradiation for rectal cancer: a pooled analysis of individual patient data

BACKGROUND

Locally advanced rectal cancer is usually treated with preoperative chemoradiation. After chemoradiation and surgery, 15-27% of the patients have no residual viable tumour at pathological examination, a pathological complete response (pCR). This study established whether patients with pCR have better long-term outcome than do those without pCR.

METHODS

In PubMed, Medline, and Embase we identified 27 articles, based on 17 different datasets, for long-term outcome of patients with and without pCR. 14 investigators agreed to provide individual patient data. All patients underwent chemoradiation and total mesorectal excision. Primary outcome was 5-year disease-free survival. Kaplan-Meier survival functions were computed and hazard ratios (HRs) calculated, with the Cox proportional hazards model. Subgroup analyses were done to test for effect modification by other predicting factors. Interstudy heterogeneity was assessed for disease-free survival and overall survival with forest plots and the Q test.

FINDINGS

484 of 3105 included patients had a pCR. Median follow-up for all patients was 48 months (range 0-277). 5-year crude disease-free survival was 83.3% (95% CI 78.8-87.0) for patients with pCR (61/419 patients had disease recurrence) and 65.6% (63.6-68.0) for those without pCR (747/2263; HR 0.44, 95% CI 0.34-0.57; p<0.0001). The Q test and forest plots did not suggest significant interstudy variation. The adjusted HR for pCR for failure was 0.54 (95% CI 0.40-0.73), indicating that patients with pCR had a significantly increased probability of disease-free survival. The adjusted HR for disease-free survival for administration of adjuvant chemotherapy was 0.91 (95% CI 0.73-1.12). The effect of pCR on disease-free survival was not modified by other prognostic factors.

INTERPRETATION

Patients with pCR after chemoradiation have better long-term outcome than do those without pCR. pCR might be indicative of a prognostically favourable biological tumour profile with less propensity for local or distant recurrence and improved survival.

FUNDING

None.

Clinical implications of the tumor volume reduction rate in head-and-neck cancer during definitive intensity-modulated radiotherapy for organ preservation

PURPOSE

To investigate the prognostic value of the volume reduction rate (VRR) in patients with head-and-neck cancer treated with intensity-modulated radiotherapy (IMRT).

METHODS AND MATERIALS

Seventy-six patients with oropharyngeal cancer (OPC) and another 76 with hypopharyngeal cancer (HPC) were enrolled in volumetric analysis. All patients received allocated radiotherapy courses. Adaptive computed tomography was done 4 to 5 weeks after the start of IMRT. Primary tumor volume measurement was derived using separate images for the pretreatment gross tumor volume (pGTV) and the interval gross tumor volume.

RESULTS

In the OPC group, the pGTV ranged from 6.6 to 242.6 mL (mean, 49.9 mL), whereas the value of the VRR ranged from 0.014 to 0.74 (mean, 0.43). In HPC patients, the pGTV ranged from 4.1 to 152.4 mL (mean, 35.6 mL), whereas the VRR ranged from -1.15 to 0.79 (mean, 0.33). Multivariate analysis of the primary tumor relapse-free survival for OPC revealed three prognostic factors: T4 tumor (p = 0.0001, hazard ratio 7.38), pGTV ≥20 mL (p = 0.01, hazard ratio 10.61), and VRR <0.5 (p = 0.001, hazard ratio 6.49). Multivariate analysis of the primary tumor relapse-free survival for HPC showed two prognostic factors: pGTV ≥30 mL (p = 0.001, hazard ratio 2.87) and VRR <0.5 (p = 0.03, hazard ratio 2.25).

CONCLUSION

The VRR is an outcome predictor for local control in OPC and HPC patients treated with IMRT. Those with large tumor volumes or a VRR <0.5 should be considered for a salvage operation or a dose-escalation scheme.

Neo-adjuvant chemo-radiation of rectal cancer with volumetric modulated arc therapy: summary of technical and dosimetric features and early clinical experience

BACKGROUND

To report about initial technical and clinical experience in preoperative radiation treatment of rectal cancer with volumetric modulated arcs with the RapidArc (RA) technology.

METHODS

Twenty-five consecutive patients (pts) were treated with RA. All showed locally advanced rectal adenocarcinoma with stage T2-T4, N0-1. Dose prescription was 44 Gy in 22 fractions (or 45 Gy in 25 fractions). Delivery was performed with single arc with a 6 MV photon beam. Twenty patients were treated preoperatively, five did not receive surgery. Twenty-three patients received concomitant chemotherapy with oral capecitabine. A comparison with a cohort of twenty patients with similar characteristics treated with conformal therapy (3DC) is presented as well.

RESULTS

From a dosimetric point of view, RA improved conformality of doses (CI95% = 1.1 vs. 1.4 for RA and 3DC), presented similar target coverage with lower maximum doses, significant sparing of femurs and significant reduction of integral and mean dose to healthy tissue. From the clinical point of view, surgical reports resulted in a down-staging in 41% of cases. Acute toxicity was limited to Grade 1-2 diarrhoea in 40% and Grade 3 in 8% of RA pts, 45% and 5% of 3DC pts, compatible with known effects of concomitant chemotherapy. RA treatments were performed with an average of 2.0 vs. 3.4 min of 3DC.

CONCLUSION

RA proved to be a safe, qualitatively advantageous treatment modality for rectal cancer, showing some improved results in dosimetric aspects.

Locally advanced rectal carcinoma treated with preoperative chemotherapy and radiation therapy: preliminary analysis of diffusion-weighted MR imaging for early detection of tumor histopathologic downstaging

PURPOSE

To determine whether changes in apparent diffusion coefficients (ADCs) of rectal carcinoma obtained 1 week after the beginning of chemotherapy and radiation therapy (CRT) correlate with tumor histopathologic downstaging after preoperative CRT.

MATERIALS AND METHODS

This prospective study was approved by an institutional review board; informed consent was obtained from all patients. Thirty-seven patients (mean age, 54.7 years; 13 women, 24 men) with primary rectal carcinoma who were undergoing preoperative CRT were recruited for the study. Diffusion-weighted (DW) magnetic resonance (MR) imaging was performed with a 1.5-T MR imager in all patients before therapy, at the end of the 1st and 2nd week of therapy, and before surgery. Tumor ADCs were calculated. Linear mixed-effects modeling was applied to analyze change in ADCs and volumes following treatment.

RESULTS

Patients were assigned to the tumor downstaged group (n = 17) or the tumor nondownstaged group (n = 20) on the basis of histopathologic examination results following surgery. Before CRT, the mean tumor ADC in the downstaged group was lower than that in the nondownstaged group (1.07 x 10(-3) mm(2)/sec +/- 0.13 [standard deviation] vs 1.19 x 10(-3) mm(2)/sec +/- 0.15, F = 6.91, P = .013). At the end of the 1st week of CRT, the mean tumor ADC increased significantly from 1.07 x 10(-3) mm(2)/sec +/- 0.13 to 1.32 x 10(-3) mm(2)/sec +/- 0.16 (F = 37.63, P <.001) in the downstaged group, but there was no significant ADC increase in the nondownstaged group (F = 1.18, P = .291). The mean percentage of tumor ADC change in the downstaged group was significantly higher than that in the nondownstaged group at each time point (F = 18.39, P < .001).

CONCLUSION

Early increase of mean tumor ADC and low pretherapy mean ADC in rectal carcinoma correlate with good response to CRT. DW MR imaging is a promising noninvasive technique for helping predict and monitor early therapeutic response in patients with rectal carcinoma who are undergoing CRT.

Tumor volume reduction rate measured by magnetic resonance volumetry correlated with pathologic tumor response of preoperative chemoradiotherapy for rectal cancer

PURPOSE

To determine whether the tumor volume reduction rate (TVRR) measured using three-dimensional region-of-interest magnetic resonance volumetry correlates with the pathologic tumor response after preoperative chemoradiotherapy (CRT) for locally advanced rectal cancer.

METHODS AND MATERIALS

The study included 405 patients with locally advanced rectal cancer (cT3-T4) who had undergone preoperative CRT and radical proctectomy. The tumor volume was measured using three-dimensional region-of-interest magnetic resonance volumetry before and after CRT but before surgery. We analyzed the correlation between the TVRR and the pathologic tumor response in terms of downstaging and tumor regression grade (TRG). Downstaging was defined as ypStage 0-I (ypT0-T2N0M0), and the TRG proposed by Dworak et al. was used.

RESULTS

The mean TVRR was 65.0% +/- 22.3%. Downstaging and complete regression occurred in 167 (41.2%) and 58 (14.3%) patients, respectively. The TVRRs according to ypT classification (ypT0-T2 vs. ypT3-T4), ypN classification (ypN0 vs. ypN1-N2), downstaging (ypStage 0-I vs. ypStage II-III), good regression (TRG 3-4 vs. TRG 1-2), and complete regression (TRG 4 vs. TRG 1-3) were all significantly different (p <.05). When the TVRR was categorized into three groups (<60%, 60-80%, and >80%), the rates of ypT0-T2, ypN0, downstaging, and good regression were all significantly greater for patients with a TVRR of >or=60%, as was the complete regression rate for patients with a TVRR >80% (p <.05).

CONCLUSION

The TVRR measured using three-dimensional region-of-interest magnetic resonance volumetry correlated significantly with the pathologic tumor response in terms of downstaging and TRG after preoperative CRT for locally advanced rectal cancer.

Transrectal ultrasonography in preoperative staging of rectal carcinoma: diagnostic value and relationship with TNM staging

AIM: To investigate the diagnostic value of transrectal ultrasonography (TRUS) in preoperative staging of rectal carcinoma and the relationship between TRUS and TNM staging.

METHODS: Sixty-five patients with pathologically confirmed rectal carcinoma were detected by TRUS before surgery. The circumference of the bowel wall involved by tumor was recorded. The preoperative transrectal ultrasonographic staging of rectal carcinoma was performed using the TNM staging system. The preoperative staging results were then compared with those of postoperative pathologic staging.

RESULTS: The overall accuracy rate of preoperative staging of rectal carcinoma by TRUS was 86.15%. The diagnostic accuracy in T₁-T₄-stage patients by TRUS was 93.85%, 87.69%, 90.77% and 100%, respectively. The circumference of the bowel wall involved by tumor was positively correlated with pathological tumor stage (r = 0.89, P < 0.01). The overall accuracy rate of preoperative staging of rectal carcinoma by TRUS in combination with the circumference of the bowel wall involved by tumor was 95.38%.

CONCLUSION: TRUS has a high diagnostic accuracy in preoperative staging of rectal carcinoma. TRUS in combination with the circumference of the bowel wall involved by tumor can improve the diagnostic accuracy of preoperative staging of rectal carcinoma.

Factors associated with local recurrence after neoadjuvant chemoradiation with total mesorectal excision for rectal cancer

BACKGROUND

The purpose of the present study was to investigate risk factors associated with local recurrence in patients with locally advanced rectal cancer who received preoperative chemoradiotherapy in combination with total mesorectal excision (TME).

METHODS

Rectal cancer patients who were treated with neoadjuvant chemoradiation with TME were studied. We compared 26 patients who developed local recurrence with 119 recurrence-free patients during the follow-up period.

RESULTS

The median follow-up period was 52 months (range: 14-131 months). Based on the use of univariate and multivariate analyses, circumferential margin involvement (p = 0.02), the presence of lymphovascular or perineural invasion (p = 0.02), and positive nodal disease (p = 0.03) were contributing factors for local recurrence. The local recurrence rate was different between ypN(+) patients and ypN(-) patients with more than 12 nodes retrieved (p = 0.01). There was no difference in local recurrence rates between ypN(+) patients and ypN(-) patients with < 12 nodes (p = 0.35) or between ypN(-) patients with < 12 nodes or > or = 12 nodes (p = 0.18).

CONCLUSIONS

Patients with circumferential margin involvement, the presence of lymphovascular or perineural invasion, and positive nodal disease should be regarded as a high-risk group. We also determined that lymph node retrieval (< 12 nodes) in patients with node-negative disease was a risk factor for local recurrence.

Tumor volume changes assessed by three-dimensional magnetic resonance volumetry in rectal cancer patients after preoperative chemoradiation: the impact of the volume reduction ratio on the prediction of pathologic complete response

PURPOSE

The aim of this study was to determine the correlation between tumor volume changes assessed by three-dimensional (3D) magnetic resonance (MR) volumetry and the histopathologic tumor response in rectal cancer patients undergoing preoperative chemoradiation therapy (CRT).

METHODS AND MATERIALS

A total of 84 patients who underwent preoperative CRT followed by radical surgery were prospectively enrolled in the study. The post-treatment tumor volume and tumor volume reduction ratio (% decrease ratio), as shown by 3D MR volumetry, were compared with the histopathologic response, as shown by T and N downstaging and the tumor regression grade (TRG).

RESULTS

There were no significant differences in the post-treatment tumor volume and the volume reduction ratio shown by 3D MR volumetry with respect to T and N downstaging and the tumor regression grade. In a multivariate analysis, the tumor volume reduction ratio was not significantly associated with T and N downstaging. The volume reduction ratio (>75%, p = 0.01) and the pretreatment carcinoembryonic antigen level (< or =3 ng/ml, p = 0.01), but not the post-treatment volume shown by 3D MR (< or = 5 ml), were, however, significantly associated with an increased pathologic complete response rate.

CONCLUSION

More than 75% of the tumor volume reduction ratios were significantly associated with a high pathologic complete response rate. Therefore, limited treatment options such as local excision or simple observation might be considered after preoperative CRT in this patient population.

Locally advanced rectal cancer: MR imaging for restaging after neoadjuvant radiation therapy with concomitant chemotherapy. Part I. Are we able to predict tumor confined to the rectal wall?

PURPOSE

To retrospectively assess accuracy of magnetic resonance (MR) imaging after radiation therapy with concomitant chemotherapy for downsizing of the primary lesion to ypT0-2 tumor confined to rectal wall in locally advanced rectal cancer, with histopathologic findings as reference standard, and to evaluate additional value of volumetric analysis.

MATERIALS AND METHODS

The institutional review board approved the study and waived informed consent. Sixty-seven patients met criteria of the study. T2-weighted MR images obtained before and after radiation therapy with concomitant chemotherapy were assessed for tumor stage by expert abdominal radiologist, colorectal surgeon, and general radiologist. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated; tumor volume was measured (compared with Mann-Whitney U test). Findings were correlated with histopathologic findings.

RESULTS

Sixty-seven patients (38 men, 29 women; mean age, 63 years) who underwent radiation therapy with concomitant chemotherapy and surgery (all but one) were evaluated. The PPV for prediction of tumor confined to rectal wall (ypT0-2) was 91% (10 of 11), 86% (six of seven), and 88% (seven of eight) for expert abdominal radiologist, surgeon, and general radiologist, respectively. In 24 patients, sensitivity was 42% (10), 25% (six), and 29% (seven). ypT0-2 tumors had significantly smaller volumes than did ypT3-4 tumors before radiation therapy with concomitant chemotherapy (55 vs 92 cm(3), P = .038). Volume reduction rates were significantly higher in ypT0-2 than in ypT3-4 tumors (89% vs 61%, P < .001). If volume before radiation therapy with concomitant chemotherapy was 50 cm(3) or smaller and volume reduction rate was 75% or higher, excised tumor was always confined to rectal wall (ypT0-2). By using these criteria, 43% (six of 14) of cases with overstaging could have been predicted to be ypT0-2 tumors correctly.

CONCLUSION

Downsizing to ypT0-2 tumors can be accurately predicted by combining morphologic tumor staging predictions with results from volumetric analyses. MR images obtained after radiation therapy with concomitant chemotherapy might be helpful in more individualized treatment planning.

Locally advanced rectal cancer: MR imaging in prediction of response after preoperative chemotherapy and radiation therapy

PURPOSE

To prospectively differentiate, at magnetic resonance (MR) imaging, patients with locally advanced nonmucinous rectal cancer who will respond to long-course chemotherapy and radiation therapy (CRT) from those who will not respond, with histopathologic results as the reference standard.

MATERIALS AND METHODS

Institutional review board approval for this study was obtained, and all patients provided written informed consent. High-spatial-resolution T2-weighted MR images were acquired before and 6-8 weeks after CRT in 53 patients (33 men, 20 women; mean age, 63 years; age range, 42-79 years). Patients were categorized as responders to CRT (patients with T3 cancer that converted to T2 or a lower stage, patients with T4 cancer that converted to T3 or a lower stage) or as nonresponders (patients with stable or progressive disease). At the posttreatment MR imaging examination, a decrease in signal intensity was considered to represent a morphologic response with fibrosis. Before CRT and surgery, tumor volume was calculated at MR imaging by multiplying cross-sectional area by section thickness. Tumor length was measured at MR imaging and in the histopathologic specimen. Nodal downstaging was evaluated. The relationship between pathologic response, morphologic MR imaging response, and percentage volume reduction was evaluated with the Mann-Whitney-Wilcoxon two-sample test.

RESULTS

Morphologic response assessment with MR imaging achieved a positive predictive value (PPV) of 84.2% (32 of 38) and a negative predictive value (NPV) of 66.7% (10 of 15). Volume reduction extent (> or = 70%) was significantly different between patients in whom disease was downstaged and those in whom it was not downstaged (P = .000005) and showed additional diagnostic value, with an overall accuracy of 86.8% (46 of 53). Presurgical MR imaging and histopathologic tumor length did not show a significant difference. MR imaging accuracy for lymph node (N) stage was 86.8% (46 of 53) on the basis of morphologic criteria.

CONCLUSION

After CRT, morphologic and volumetric evaluation at MR imaging had a high PPV and a low NPV for response assessment. The detection of small clusters of residual tumor cells within fibrosis remains a problem.

SUPPLEMENTAL MATERIAL

http://radiology.rsnajnls.org/cgi/content/full/250/3/730/DC1.