Relative Value of Restaging MRI, CT, and FDG-PET Scan After Preoperative Chemoradiation for Rectal Cancer

Application of spectral CT in diagnosis, classification and prognostic monitoring of gastrointestinal cancers: progress, limitations and prospects

Gastrointestinal (GI) cancer is the leading cause of cancer-related deaths worldwide. Computed tomography (CT) is an important auxiliary tool for the diagnosis, evaluation, and prognosis prediction of gastrointestinal tumors. Spectral CT is another major CT revolution after spiral CT and multidetector CT. Compared to traditional CT which only provides single-parameter anatomical diagnostic mode imaging, spectral CT can achieve multi-parameter imaging and provide a wealth of image information to optimize disease diagnosis. In recent years, with the rapid development and application of spectral CT, more and more studies on the application of spectral CT in the characterization of GI tumors have been published. For this review, we obtained a substantial volume of literature, focusing on spectral CT imaging of gastrointestinal cancers, including esophageal, stomach, colorectal, liver, and pancreatic cancers. We found that spectral CT can not only accurately stage gastrointestinal tumors before operation but also distinguish benign and malignant GI tumors with improved image quality, and effectively evaluate the therapeutic response and prognosis of the lesions. In addition, this paper also discusses the limitations and prospects of using spectral CT in GI cancer diagnosis and treatment.

Evaluation of survival of the patients with metastatic rectal cancer by staging 18F-FDG PET/CT radiomic and volumetric parameters

OBJECTIVE

The aim of this study is to predict the prognosis in patients with metastatic rectal cancer (mRC) by obtaining a model with machine learning (ML) algorithms through volumetric and radiomic data obtained from baseline 18-Fluorine Fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) images.

METHODS

Sixty-two patients with mRC who underwent 18F-FDG PET/CT imaging for staging between January 2015 and January 2021 were evaluated using LIFEx software. The volume of interest (VOI) of the primary tumor was generated and volumetric and textural features were obtained from this VOI. In addition, metabolic tumor volume (tMTV) and total lesion glycolysis (tTLG) values of tumor foci in the whole body. Clinical and radiomic data were evaluated with ML algorithms to create a model that predicts survival. Significant associations between these features and 1-year and 2-year survival were investigated.

RESULTS

Random forest algorithm was the most successful algorithm in predicting 2-year survival (AUC: 0.843, PRC: 0.822, and MCC: 0.583). The model obtained with this algorithm was able to predict 49 patients with 79.03% accuracy. While tMTV and tTLG values were successful in predicting 1-year survival (p: 0.002 and 0.007, respectively), texture characteristics from the primary tumor did not show a significant relationship with 1-year survival.

CONCLUSIONS

In addition to the important role of 18F-FDG PET/CT in staging patients with mRC, this study shows that it is possible to predict survival with ML methods, with parameters obtained using texture analysis from the primary tumor and whole body volumetric parameters.

The Role of Preoperative Imaging in the Detection of Lateral Lymph Node Metastases in Rectal Cancer: A Systematic Review and Diagnostic Test Meta-analysis

BACKGROUND

Different techniques exist for the imaging of lateral lymph nodes in rectal cancer.

OBJECTIVE

This study aimed to compare the diagnostic accuracy of pelvic MRI, 18 F-FDG-PET/CT, and 18 F-FDG-PET/MRI for the identification of lateral lymph node metastases in rectal cancer.

DATA SOURCES

Data sources include PubMed, Embase, Cochrane Library, and Google Scholar.

STUDY SELECTION

All studies evaluating the diagnostic accuracy of pelvic MRI, 18 F-FDG-PET/CT, and 18 F-FDG-PET/MRI for the preoperative detection of lateral lymph node metastasis in patients with rectal cancer were selected.

INTERVENTIONS

The interventions were pelvic MRI, 18 F-FDG-PET/CT, and/or 18 F-FDG-PET/MRI.

MAIN OUTCOME MEASURES

Definitive histopathology was used as a criterion standard.

RESULTS

A total of 20 studies (1,827 patients) were included out of an initial search yielding 7,360 studies. The pooled sensitivity of pelvic MRI was 0.88 (95% CI, 0.85-0.91), of 18 F-FDG-PET/CT was 0.83 (95% CI, 0.80-0.86), and of 18 F-FDG-PET/MRI was 0.72 (95% CI, 0.51-0.87) for the detection of lateral lymph node metastasis. The pooled specificity of pelvic MRI was 0.85 (95% CI, 0.78-0.90), of 18 F-FDG-PET/CT was 0.95 (95% CI, 0.86-0.98), and of 18 F-FDG-PET/MRI was 0.90 (95% CI, 0.78-0.96). The area under the curve was 0.88 (95% CI, 0.85-0.91) for pelvic MRI and was 0.83 (95% CI, 0.80-0.86) for 18 F-FDG-PET/CT.

LIMITATIONS

Heterogeneity in terms of patients' populations, definitions of suspect lateral lymph nodes, and administration of neoadjuvant treatment.

CONCLUSIONS

For the preoperative identification of lateral lymph node metastasis in rectal cancer, this review found compelling evidence that pelvic MRI should constitute the imaging modality of choice. In contrast, to confirm the presence of lateral lymph node metastasis, 18 F-FDG-PET/MRI modalities allow discarding false positive cases because of increased specificity.

PROSPERO REGISTRATION NUMBER

CRD42020200319.

ACR Appropriateness Criteria® Staging of Colorectal Cancer: 2021 Update

Preoperative imaging of rectal carcinoma involves accurate assessment of the primary tumor as well as distant metastatic disease. Preoperative imaging of nonrectal colon cancer is most beneficial in identifying distant metastases, regardless of primary T or N stage. Surgical treatment remains the definitive treatment for colon cancer, while organ-sparing approach may be considered in some rectal cancer patients based on imaging obtained before and after neoadjuvant treatment. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

A decade of multi-modality PET and MR imaging in abdominal oncology

OBJECTIVES

To investigate trends observed in a decade of published research on multimodality PET(/CT)+MR imaging in abdominal oncology, and to explore how these trends are reflected by the use of multimodality imaging performed at our institution.

METHODS

First, we performed a literature search (2009-2018) including all papers published on the multimodality combination of PET(/CT) and MRI in abdominal oncology. Retrieved papers were categorized according to a structured labelling system, including study design and outcome, cancer and lesion type under investigation and PET-tracer type. Results were analysed using descriptive statistics and evolutions over time were plotted graphically. Second, we performed a descriptive analysis of the numbers of MRI, PET/CT and multimodality PET/CT+MRI combinations (performed within a ≤14 days interval) performed during a similar time span at our institution.

RESULTS

Published research papers involving multimodality PET(/CT)+MRI combinations showed an impressive increase in numbers, both for retrospective combinations of PET/CT and MRI, as well as hybrid PET/MRI. Main areas of research included new PET-tracers, visual PET(/CT)+MRI assessment for staging, and (semi-)quantitative analysis of PET-parameters compared to or combined with MRI-parameters as predictive biomarkers. In line with literature, we also observed a vast increase in numbers of multimodality PET/CT+MRI imaging in our institutional data.

CONCLUSIONS

The tremendous increase in published literature on multimodality imaging, reflected by our institutional data, shows the continuously growing interest in comprehensive multivariable imaging evaluations to guide oncological practice.

ADVANCES IN KNOWLEDGE

The role of multimodality imaging in oncology is rapidly evolving. This paper summarizes the main applications and recent developments in multimodality imaging, with a specific focus on the combination of PET+MRI in abdominal oncology.

MRI accuracy and interobserver agreement in locally advanced cervix carcinoma

OBJECTIVES

The main standard of care for locally advanced cervix carcinoma (LACC) is radiochemotherapy (RCT) followed by brachytherapy. A surgical approach may still be discussed based on pelvic MRI-derived residual tumour evaluation. As no interobserver agreement study has ever been conducted to our knowledge, the aim of the present study was to report on pelvic MRI accuracy and interobserver agreement in LACC.

METHODS

We carried out a retrospective study in a French university hospital. Medical records of all consecutive patients treated with curative intent for LACC by RCT followed by brachytherapy and completion pelvic surgery between January 2014 and January 2020 were reviewed. Local response was assessed through pelvis MRI and histological analysis after completion surgery. MRI data were independently evaluated by two radiologists with varying experience. The two main interobserving criteria we used were complete response and residual tumour.

RESULTS

23 patients fulfilled the inclusion criteria. Agreement between the junior and senior radiologist was moderate to strong. Indeed, regarding main criteria, κ was 0.65 for complete response and 0.57 for residual tumour. Interestingly, the present study shows a lower sensitivity whatever the radiologists than in the international literature.

CONCLUSION

The present study highlights a low interobserver variability regarding pelvic MRI in the assessment of RCT followed by brachytherapy in LACC. Yet, sensitivity was lower than in literature.

ADVANCES IN KNOWLEDGE

Radiology is part of treatment decision-making, the issue of heterogeneity regarding radiologists' training and experience to cancer (sensitivity and specificity) turns essential, so does MRI accuracy.

Staging of Locally Advanced Rectal Cancer Beyond TME

The management of rectal cancer is complex and continually evolving. With advancements in technology and the use of multidisciplinary teams to guide the treatment decision making, staging, oncologic, and functional outcomes are improving, and the management is moving toward personalized treatment strategies to optimize each individual patient's outcomes. Key in this evolution is imaging. Magnetic resonance imaging (MRI) has emerged as the dominant method of pelvic imaging in rectal cancer, and use of MRI for staging is best practice in multiple international guidelines. MRI allows a noninvasive assessment of the tumor site, relationship to surrounding structures, and provides highly accurate rectal cancer staging, which is necessary for determining the appropriate treatment strategy. However, the applications of MRI extend far beyond pretreatment staging. MRI can be used to predict outcomes in locally advanced rectal cancer and guide the surgical or nonsurgical plan, serving as a predictive and prognostic biomarker. With continued MRI hardware improvement and new sequence development, MRI may offer new perspectives in the assessment of treatment response and new innovations that could provide better insight into the staging, restaging, and outcomes with rectal cancer.

What Is the Utility of Restaging Imaging for Patients With Clinical Stage II/III Rectal Cancer After Completion of Neoadjuvant Chemoradiation and Prior to Proctectomy?

BACKGROUND

In the United States, patients with clinical stage II or III rectal cancer typically receive neoadjuvant chemoradiation therapy (chemo/XRT) over a 5-6 week period followed by a 6-10 week break prior to proctectomy. In the current study, we evaluate the utilization of restaging studies performed and detection of disease progression during this window.

METHODS

A retrospective review of patients with clinical stage II/III rectal cancer was performed. Medical records were analyzed to collect clinicopathologic data and the performance and results of preoperative, early postoperative, and first surveillance CT and/or PET/CT in patients completing long course neoadjuvant chemo/XRT and undergoing proctectomy.

RESULTS

Between 2005 and 2017, 176 patients with clinical stage II or III rectal adenocarcinoma completed neoadjuvant chemo/XRT and underwent proctectomy. Preoperative restaging with CT CAP and/or CT/PET was performed in 72 (40.9%) patients with no detection of disease progression. Of the 104 patients without preoperative restaging, 1 had intraoperative detection of liver metastases and 31 had early postoperative reimaging (within 30 days of proctectomy) of which 2 had detection of new pulmonary metastases. Among 72 patients with no preoperative or early postoperative reimaging, first surveillance imaging was available in 47 and detected new metastases in 8 (17%).

DISCUSSION

In patients with clinical stage II/III rectal cancer who undergo long course neoadjuvant chemo/XRT, perioperative reimaging with CT CAP and/or PET/CT detects new metastases in a small percentage of patients. A multi-institutional, prospective analysis using standardized staging protocols is warranted to better determine the value of preoperative restaging in these patients.

Limited Role for Routine Restaging After Neoadjuvant Therapy in Locally Advanced Rectal Cancer

BACKGROUND

Although many patients with locally advanced rectal cancer undergo restaging imaging after neoadjuvant chemoradiotherapy and before surgery, the benefit of this practice is unclear. The purpose of this study was to examine the impact of reimaging on outcomes.

MATERIALS AND METHODS

We performed a retrospective analysis of consecutive patients with stage 2 and 3 rectal adenocarcinoma treated with neoadjuvant chemoradiotherapy between May 2005 and April 2018. Patient and disease characteristics, imaging, treatment, and oncologic outcomes were compared between those who underwent restaging and those who went directly to surgery. Predictors of outcomes and cost effectiveness of restaging were determined.

RESULTS

Of 224 patients, 146 underwent restaging. Six restaged patients had findings leading to a change in management. There was no difference in freedom from recurrence (P = 0.807) and overall survival (P = 0.684) based on restaging. Pretreatment carcinoembryonic antigen level >3 ng/mL (P = 0.010), clinical T stage 4 (P = 0.016), and pathologic T4 (P = 0.047) and N2 (P = 0.002) disease increased the risk of death, whereas adjuvant chemotherapy decreased the risk of death (P < 0.001) on multivariate analysis. Disease recurrence was lower with pelvic exenteration (P = 0.005) and in females (P = 0.039) and higher with pathologic N2 (P = 0.003) and N3 (P = 0.002) disease. The average cost of reimaging is $40,309 per change in management; however, $45 is saved per patient when downstream surgical costs are considered.

CONCLUSIONS

Imaging restaging after neoadjuvant chemoradiotherapy in patients with locally advanced rectal cancer rarely changes treatment and does not improve survival. In a subset of patients at higher risk for worse outcome, reimaging may be beneficial.

18F-FDG PET/MRI for Rectal Cancer TNM Restaging After Preoperative Chemoradiotherapy: Initial Experience

OBJECTIVE

F-FDG-PET/MRI is a novel hybrid techinque that has been recently introduced in oncological imaging, showing promising results. The aim of this study is to assess the value of whole-body F-FDG-PET/MRI for predicting the pathological stage of locally advanced rectal cancer after preoperative chemoradiotherapy.

DESIGN

This was a prospective observational study.

SETTINGS

The study was conducted at a tertiary care hospital.

PATIENTS

Thirty-six patients with locally advanced rectal cancer (25 male, median age 68.5 years) were prospectively assessed with PET/MRI and thoracoabdominal CT before and after preoperative chemoradiotherapy. Twenty-seven patients underwent low anterior or abdominoperineal resection. Nine patients with a complete clinical response underwent organ-preserving treatment (8 local excision and 1 watch-and-wait approach) with >1-year follow-up.

MAIN OUTCOME MEASURES

One radiologist evaluated pelvic MRI and CT. A second radiologist and a nuclear medicine physician jointly assessed PET/MRI. The imaging was compared with histology or follow-up (ypT0 vs T ≥1 and ypN0 vs ypN+ categories). Metastases were confirmed with biopsy or a follow-up CT scan at least at 1 year after preoperative chemoradiotherapy. The sensitivity, specificity, and accuracy values of the imaging techniques were calculated using standard formulas.

RESULTS

The accuracy for ypT staging was 89% and 92%, and the accuracy for ypN was 86% and 92% for MRI and PET/MRI. Compared with CT, PET/MRI correctly diagnosed 4 of 5 metastases, but it did not detect a lung metastatic nodule. In 11% of the patients, the PET/MRI changed the treatment strategy.

LIMITATIONS

This study is limited by its small sample size.

CONCLUSIONS

Although the whole-body PET/MRI was more accurate than the pelvic MRI alone for the prediction of tumor and node response to preoperative chemoradiotherapy, the technique performed worse than CT in detecting small lung metastasis. See Video Abstract at http://links.lww.com/DCR/B108. TOMOGRAFÍA POR EMISIÓN DE POSITRONES DE 18F- FLUORODEOXIGLUCOSA (FDG) / RESONANCIA MAGNÉTICA (TEP/RM) PARA ESTADIFICACIÓN TUMORAL TNM DE CÁNCER DEL RECTO DESPUÉS DE LA QUIMIORRADIOTERAPIA PREOPERATORIA - EXPERIENCIA INICIAL: Evaluar el valor de la tomografía por emisión de positrones de 18F-fluorodeoxiglucosa / resonancia magnética (TEP/RM) para predecir el estadio patológico del cáncer de recto localmente avanzado después de la quimiorradioterapia preoperatoria.Este fue un estudio prospectivo observacional.El estudio se realizó en un hospital de atención terciaria.Treinta y seis pacientes con cáncer rectal localmente avanzado (25 hombres, edad media de 68.5 años) fueron evaluados prospectivamente con TEP/RM y tomografía computarizada (TC) toraco-abdominal antes y después de la quimiorradioterapia preoperatoria. Veintisiete pacientes se sometieron a resección anterior baja o abdominoperineal. Nueve pacientes con una respuesta clínica completa se sometieron a un tratamiento de preservación de órganos (8 escisión local y 1 un enfoque de observar y esperar) con un seguimiento de> 1 año.Un radiólogo evaluó la RM pélvica y la TC. Un segundo radiólogo y un médico de medicina nuclear evaluaron conjuntamente TEP / RM. La imagen se comparó con la histología o el seguimiento (ypT0 vs T ≥1 y ypN0 vs ypN + categorías). Las metástasis se confirmaron con biopsia o una TC de seguimiento al menos 1 año después de la quimiorradioterapia preoperatoria. Los valores de sensibilidad, especificidad y precisión de las técnicas de imagen se calcularon utilizando fórmulas estándar.La precisión para la estadificación ypT fue del 89% y 92%, y la precisión para ypN fue del 86% y 92% para RM y TEP/RM respectivamente. En comparación con la TC, la TEP / RM diagnosticó correctamente 4 de 5 metástasis, pero no detectó un nódulo metastásico pulmonar. En el 11% de los pacientes, la TEP / RM cambió la estrategia de tratamiento.Este estudio está limitado por su pequeño tamaño de muestra.Si bien la TEP / RM de todo el cuerpo fue más precisa que la RM pélvica sola para la predicción de la respuesta tumoral y ganglionar a la quimiorradioterapia preoperatoria, la técnica funcionó peor que la TC para detectar metástasis pulmonares pequeños. Consulte Video Resumen en http://links.lww.com/DCR/B108.

Restaging Patients with Rectal Cancer Following Neoadjuvant Chemoradiation: A Systematic Review

BACKGROUND

In the USA, most patients with clinical stage II/III rectal cancer receive neoadjuvant chemoradiation (chemo/XRT) over 5-6 weeks followed by a 6-10-week break before proctectomy. As chemotherapy is delivered at radio-sensitizing doses, there is essentially a 3-month window during which potential systemic disease is untreated. Evidence regarding the utility of restaging patients prior to proctectomy is limited.

METHODS

PubMed, Scopus, Web of Science, and the Cochrane Library were searched for studies evaluating the utility of restaging patients with rectal cancer after completion of long-course chemo/XRT, and reporting associated changes in management. Studies that were non-English, included <50 patients, or examining the diagnostic accuracy of imaging modalities were excluded. Study quality was evaluated using the modified Newcastle Ottawa Scale.

RESULTS

Eight studies were identified including a total of 1251 patients restaged between completion of chemo/XRT and proctectomy. All studies were retrospective. Restaging identified new metastatic disease in 72 (6.0%) patients, with 4 studies reporting specific sites: liver (n = 28), lung (n = 8), adrenal (n = 1), bone (n = 1), and multiple sites (n = 7). Overall progression (distant or local) was detected in 88 (7.0%) patients and resulted in a change in management in 77 (87.5%) of these patients. Tumor-related prognostic characteristics were inconsistently reported among studies, precluding meta-analysis.

CONCLUSIONS

Although restaging between completion of neoadjuvant chemo/XRT and proctectomy detects disease progression in only a small percentage of patients, findings alter the treatment plan in the vast majority of these patients. Multi-institutional collaboration with analysis of well-defined prognostic variables may better identify patients most likely to benefit from restaging.

Predictive Value of [18F]FDG PET/CT for Lymph Node Metastasis in Rectal Cancer

[¹⁸F]Fluorodeoxyglucose ([¹⁸F]FDG) Positron emission tomography/computed tomography (PET/CT) is commonly used for rectal cancer staging, but improved diagnostic methods for nodal metastases are needed. We aimed to evaluate whether the combination model of the metabolic tumor volume of primary tumor (T_MTV) and maximum standardized uptake value of lymph node (N_SUVmax) on pretreatment [¹⁸F]FDG PET/CT could improve nodal metastases prediction in rectal cancer. We enrolled a total of 166 rectal cancer patients who underwent pretreatment [¹⁸F]FDG PET/CT and surgical resection without neoadjuvant treatment between January 2009 and August 2016. Visual and semiquantitative PET/CT parameters were obtained. Associations between clinicopathological, PET/CT-derived variables and nodal metastases were evaluated by logistic regression analysis. Nodal metastases were confirmed histologically in 68 of the 166 patients (41%). Uni- and multivariate analyses demonstrated T_MTV and N_SUVmax were independent predictive factors for nodal metastases. The c-statistics of the combination model was 0.806 (Standard Error, 0.034; 95% Confidence Interval, 0.737-0.863), which showed significant improvement compared to T_MTV (0.698, P = 0.0002) or N_SUVmax (0.720, P = 0.0008) alone. T_MTV and N_SUVmax are independently correlated with nodal metastases. Furthermore, the combination model showed improved performance for risk prediction; thus, [¹⁸F]FDG PET/CT might have a role in rectal cancer staging and treatment planning.

Molecular Imaging Using PET/CT for Radiation Therapy Planning for Adult Cancers: Current Status and Expanding Applications

Accurate tumor delineation is a priority in radiation therapy (RT). Metabolic imaging has a key and evolving role in target volume selection and delineation. This is especially so for non-small cell lung cancer, squamous cell cancer of the head and neck, and lymphoma, for which positron emission tomography/computed tomography (PET/CT) is complimentary to structural imaging modalities, not only in delineating primary tumors, but also often in revealing previously undiagnosed regional nodal disease. At some sites, PET/CT has been confirmed to enable target size reduction compared with structural imaging alone, with enhanced normal tissue sparing and potentially allowing for dose escalation. These contributions often dramatically affect RT strategies. However, some limitations exist to the use of fluorodeoxyglucose-PET in RT planning, including its relatively poor spatial resolution and partial voluming effects for small tumors. A role is developing for contributions from metabolic imaging to RT planning at other tumor sites and exciting new applications for the use of non-fluorodeoxyglucose metabolic markers for RT planning.

Value of FDG-PET/CT Volumetry After Chemoradiotherapy in Rectal Cancer

BACKGROUND

Neoadjuvant chemoradiotherapy followed by an optimal surgery is the standard treatment for patients with locally advanced rectal cancer. FDG-PET/CT is commonly used as the modality for assessing the effect of chemoradiotherapy.

OBJECTIVE

The purpose of this study was to investigate whether PET/CT-based volumetry could contribute to the prediction of pathological complete response or prognosis after neoadjuvant chemoradiotherapy.

DESIGN

This was a retrospective cohort study.

SETTINGS

This study was conducted at a single research center.

PATIENTS

Ninety-one consecutive patients with locally advanced rectal cancer were enrolled between January 2005 and December 2015.

INTERVENTION

Patients underwent PET/CT before and after neoadjuvant chemoradiotherapy.

MAIN OUTCOME MEASURES

Maximum standardized uptake value and total lesion glycolysis on PET/CT before and after neoadjuvant chemoradiotherapy were calculated using isocontour methods. Correlations between these variables and clinicopathological factors and prognosis were assessed.

RESULTS

PET/CT-associated variables before chemoradiotherapy were not correlated with either clinicopathological factors or prognosis. Maximum standardized uptake value was associated with pathological complete response, but total lesion glycolysis was not. Maximum standardized uptake value correlated with ypT, whereas total lesion glycolysis correlated with both ypT and ypN. High total lesion glycolysis was associated with a considerably poorer prognosis; the 5-year recurrence rate was 65% and the 5-year mortality rate 42%, whereas in lesions with low total lesion glycolysis, these were 6% and 2%. On multivariate analysis, high total lesion glycolysis was an independent risk factor for recurrence (HR = 4.718; p = 0.04).

LIMITATIONS

The gain in fluoro-2-deoxy-D-glucose uptake may differ between scanners, thus the general applicability of this threshold should be validated.

CONCLUSIONS

In patients with locally advanced rectal cancer, high total lesion glycolysis after neoadjuvant chemoradiotherapy is strongly associated with a worse prognosis. Total lesion glycolysis after chemoradiotherapy may be a promising preoperative predictor of recurrence and death. See Video Abstract at http://links.lww.com/DCR/A464.

Tumor compactness improves the preoperative volumetry-based prediction of the pathological complete response of rectal cancer after preoperative concurrent chemoradiotherapy

In addition to clinical factors (tumor and node stage) and treatment factors (equivalent radiotherapy dose and chemotherapy regimen), we assessed whether different performances of various tumor volume measurements help predict the pathological complete response (pCR) of locally advanced rectal cancer (LARC) after preoperative concurrent chemoradiotherapy (CCRT). A total of 122 patients with LARC treated with a long course of CCRT, between December 2009 and March 2015, were enrolled in this bi-institutional study. Tumor delineation was based on standard T2-weighted magnetic resonance imaging or contrast-enhanced computed tomography before CCRT. Tumor compactness was defined as the ratio of the volume and the surface area. The tumor compactness-corrected TV (TCTV) was defined as the ratio of the real TV (RTV) and tumor compactness. Twenty-three (18.9%) patients had a pCR. Areas under the curve of the receiver operating characteristic for pCR prediction calculated using the RTV, cylindrical approximated TV (CATV), and TCTV were 0.724, 0.747, and 0.780, respectively. The prediction performance of TCTV was significantly more efficient than that of both RTV (P = 0.0057) and CATV (P = 0.0329). Multivariate logistic regression analysis revealed tumor compactness (P = 0.001), RTV (P = 0.042), and preoperative clinical nodal status (P = 0.044) as significant predictors of a pCR. In addition, poor tumor compactness was closely associated with lymphovascular space invasion (P = 0.008) and pathological nodal status (P = 0.003). For patients with LARC receiving preoperative CCRT, tumor compactness is a useful radiomic parameter for improving the volumetric based prediction model.

Long-Term Outcome of Rectal Cancer With Clinically (EUS/MRI) Metastatic Mesorectal Lymph Nodes Treated by Neoadjuvant Chemoradiation: Role of Organ Preservation Strategies in Relation to Pathologic Response

BACKGROUND

Organ preservation strategies are under investigation for patients with locally advanced rectal cancer (LARC) who achieve a complete pathologic response in the primary tumor (ypT0) after neoadjuvant chemoradiation therapy (CRT). This study explored the value of this approach for cN+ patients.

METHODS

Data were retrieved from our institutional prospective rectal cancer database. Tumors with mesorectal lymph nodes larger than 5 mm shown on endorectal ultrasonography, pelvic magnetic resonance imaging, or both were staged as cN+.

RESULTS

The study population comprised 226 patients (142 men and 84 women; median age, 64 years) with LARC who underwent CRT followed by surgery including total mesorectal excision (TME) (n = 179) and full-thickness local excision (LE) (n = 47) between 1996 and 2013. At staging, 123 patients (54.4 %) were cN+. In 65 cases (28.7 %), ypCR was observed. Metastatic mesorectal lymph nodes (ypN+) were detected in 41.6 % of the cN+ patients and in 2.8 % of the cN0 patients (P < 0.01). Among the cN+ patients, 16 % of the ypT0 cases were ypN+ compared with 51.8 % of the no-ypT0 cases (P < 0.01). Among the cN+ patients who underwent TME, the 5-year disease-specific survival (DSS) and disease-free survival (DFS) rates were respectively 100 and 91.6 % for the ypT0 patients compared with 71.2 and 58.0 % for the no-ypT0 patients (P = 0.01). Among the ypN+ patients, the 5-year DSS and DFS rates were both 100 % for the ypT0 cases compared with 59.1 and 43.3 % for the no-ypT0 patients. Among the cN+ and ypT0 patients, the 5-year DSS and DFS were respectively 100 and 85.7 % for the TME patients compared with 100 and 91.6 % for the LE patients. In the multivariate analysis, ypT0 was the only independent prognostic factor.

CONCLUSIONS

Protocols aimed at organ preservation in LARC that achieve ypT0 after CRT can be offered also to cN+ patients.