Factors associated with degree of tumour response to neo-adjuvant radiotherapy in rectal cancer and subsequent corresponding outcomes

MRI-Based Radiomic Models Outperform Radiologists in Predicting Pathological Complete Response to Neoadjuvant Chemoradiotherapy in Locally Advanced Rectal Cancer

RATIONALE AND OBJECTIVES

The 15%-27% of patients with locally advanced rectal cancer (LARC) achieved pathologic complete response (pCR) to neoadjuvant chemoradiotherapy (nCRT) and could avoid proctectomy. We aimed to investigate the effectiveness of treatment response prediction using MRI-based pre-, post-, and delta-radiomic features for LARC patients treated with nCRT and to compare these radiomic models with radiologists' visual assessment.

MATERIALS AND METHODS

A total of 126 patients with LARC who received nCRT before surgery were included and randomly divided into a training set (n = 84) and a validation set (n = 42). 250 radiomic features were extracted from T2-weighted images from pre- and post-nCRT MRI. Pearson correlation analysis and AONVA or Relief were used to identify radiomic descriptors associated with pCR. Five machine-learning classifiers were compared to construct radiomic models. The radiomic nomogram was built via multivariate logistic regression analysis. Two senior radiologists independently rated tumor regression grades and compared with radiomic models. Area under the curve (AUC) of the models and pooled observers were compared by using the DeLong test.

RESULTS

The optimal pre-, post-, and delta-radiomic models yielded an AUC of 0.717 (95% CI: 0.639-0.795), 0.805 (95%CI: 0.736-0.874), and 0.724 (95%CI: 0.648-0.800), respectively. The radiomic nomogram based on pre-nCRT cN stage, pre-nCRT radscore, and post-nCRT radscore achieved an AUC of 0.852 (95%CI: 0.774-0.930), which was higher than the single radiomic models and pooled readers (all p < 0.05).

CONCLUSIONS

The radiomic nomogram is an effective and invasive tool to predict pCR in LARC patients after nCRT, which outperforms radiologists.

MRI radiomics independent of clinical baseline characteristics and neoadjuvant treatment modalities predicts response to neoadjuvant therapy in rectal cancer

Background

To analyse the performance of multicentre pre-treatment MRI-based radiomics (MBR) signatures combined with clinical baseline characteristics and neoadjuvant treatment modalities to predict complete response to neoadjuvant (chemo)radiotherapy in locally advanced rectal cancer (LARC).

Methods

Baseline MRI and clinical characteristics with neoadjuvant treatment modalities at four centres were collected. Decision tree, support vector machine and five-fold cross-validation were applied for two non-imaging and three radiomics-based models’ development and validation.

Results

We finally included 674 patients. Pre-treatment CEA, T stage, and histologic grade were selected to generate two non-imaging models: C model (clinical baseline characteristics alone) and CT model (clinical baseline characteristics combining neoadjuvant treatment modalities). The prediction performance of both non-imaging models were poor. The MBR signatures comprising 30 selected radiomics features, the MBR signatures combining clinical baseline characteristics (CMBR), and the CMBR incorporating neoadjuvant treatment modalities (CTMBR) all showed good discrimination with mean AUCs of 0.7835, 0.7871 and 0.7916 in validation sets, respectively. The three radiomics-based models had insignificant discrimination in performance.

Conclusions

The performance of the radiomics-based models were superior to the non-imaging models. MBR signatures seemed to reflect LARC’s true nature more accurately than clinical parameters and helped identify patients who can undergo organ preservation strategies.

Sarcopenia assessed by skeletal muscle mass volume is a prognostic factor for oncological outcomes of rectal cancer patients undergoing neoadjuvant chemoradiotherapy followed by surgery

INTRODUCTION

Recently, sarcopenia has been reported to be associated with poor postoperative outcomes in various cancers. However, its clinical significance for rectal cancer patients undergoing neoadjuvant chemoradiotherapy (NACRT) followed by surgery remains unknown.

MATERIALS AND METHODS

This study included 46 patients with locally advanced rectal cancer who underwent curative surgery after NACRT. Sarcopenia was assessed by measuring the cross-sectional psoas muscle area (PA) at L3 and total bilateral psoas muscle volume (PV). Patients with a lower PV or PA value than the median were assigned to the sarcopenia group while others were assigned to the non-sarcopenia group. Clinical outcomes were then compared between groups.

RESULTS

The sarcopenia group included 22 patients. The rate of overall postoperative complications did not differ between groups. Five-year relapse-free survival (RFS) was significantly lower in the sarcopenia group when sarcopenia was assessed by PV after NACRT (44.0% vs. 82.6%, P = 0.00494). In contrast, RFS did not differ between groups when sarcopenia was assessed by PA. Multivariable analysis identified PV after NACRT as the most significant risk factor for RFS (hazard ratio 4.00; 95% CI 1.27-12.66, P = 0.018).

CONCLUSION

Sarcopenia assessed by total PV after NACRT may be an accurate and reliable predictor of poor oncological outcomes in rectal cancer patients.

Clinical outcome of neoadjuvant chemoradiation in rectal cancer treatment

To determine the clinical and pathological outcome of locally advanced rectal cancer patients treated with neoadjuvant chemoradiation (chemoradiotherapy [CRT]) followed by curative surgery and to identify predictive factors of pathological complete response (pCR).Locally advanced rectal cancer patients undergoing CRT followed by curative surgery from January 2012 to December 2017 were included. Patient's demographic data, pretreatment tumor characteristics, type of CRT regimens, type of surgery, postoperative complications, pathological reports and follow up records were analyzed. Univariate and multivariate analyses were applied to identify predictive factors for pCR. Five-year disease free and overall survival were estimated by Kaplan-Meier method and compared between pCR and non-pCR groups.A total of 85 patients were analyzed. Eighteen patients (21.1%) achieved pCR. The sphincter-saving surgery rate was 57.6%. After univariate analyses, tumor length >4 cm (P = .007) and positive lymph nodes (P = .040) were significantly associated with decreased rate of pCR. Complete clinical response was significantly associated with higher rate of pCR (P = .015). Multivariate analyses demonstrated that tumor length >4 cm (P = .010) was significantly associated with decreased rate of pCR. After a median follow-up of 65 months (IQR 34-79), the calculated 5-year overall survival and disease-free survival rates were 81.4% and 69.7%, respectively. Patients who achieved pCR tend to had longer 5-year disease-free survival (P = .355) and overall survival (P = .361) than those who did not.Tumor length >4 cm was associated with decreased rate of pCR in locally advanced rectal cancer who had CRT followed by surgery. Longer waiting time or more intense adjuvant treatment may be considered to improved pCR and oncological outcomes.

Can normalized carcinoembryonic antigen following neoadjuvant chemoradiation predict tumour recurrence after curative resection for locally advanced rectal cancer?

AIM

The aim of this work was to evaluate whether normalized carcinoembryonic antigen (CEA) following neoadjuvant chemoradiation predicts the prognosis following curative resection in locally advanced rectal cancer.

METHOD

Patients who underwent neoadjuvant chemoradiation and curative resection for locally advanced rectal cancer between 2010 and 2015 were divided into three groups: Group A (n = 119, normal-to-normal): normal CEA before and after neoadjuvant chemoradiation; Group B (n = 37, high-to-normal): elevated CEA before and normal CEA after neoadjuvant chemoradiation; Group C (n = 36, high-to-high): elevated CEA before and after neoadjuvant chemoradiation. Overall and disease-free survival were compared. Univariate and multivariate analyses identified potential predictors for recurrence.

RESULTS

One hundred and ninety two patients [median age 59 years (range 31-87), 65.1% male] were identified: 54.7% had low rectal cancer: 12.5% were clinical stage T4 and 70.3% were clinically node positive; 21.9% achieved complete pathological response; 24.5% had abdominoperineal resection (APR); and 70.3% underwent adjuvant chemotherapy following curative resection. Significantly more patients in Group C underwent APR (p = 0.0209), had advanced pathological T stage (P = 0.0065) and a higher prevalence of perineural invasion (p = 0.0042). Overall and disease-free survival were significantly higher for Group A than for Group C [hazard ratio (HR) = 4.32, 95% CI = 1.66-11.21, p = 0.0026 and HR=2.68, 95% CI = 1.33-5.40, p = 0.0057, respectively]. No significant difference was noted between Groups A and B for overall (p = 0.0591) or disease-free (p = 0.2834) survival. Another risk factor associated with recurrence and death was clinical T4 stage; nodal positivity was a risk factor only for recurrence.

CONCLUSION

Elevated CEA after neoadjuvant chemoradiation and clinical stage T4 disease were unfavourable predictors for overall and disease-free survival. Normalized CEA during neoadjuvant chemoradiation may serve as a prognosticator, although pretreatment CEA may significantly affect survival.

Resistance to Cell Death in Mucinous Colorectal Cancer-A Review

Mucinous colorectal cancer (CRC) is estimated to occur in approximately 10-15% of CRC cases and is characterized by abundant extracellular mucin. Mucinous CRC is frequently associated with resistance to apoptosis. Inferior prognosis is observed in mucinous CRC, particularly in rectal cancer and metastatic cases. Mucins are heavily glycosylated secretory or transmembrane proteins that participate in protection of the colonic epithelium. MUC2 overexpression is a hallmark of mucinous CRCs. Mucinous CRC is associated with KRAS and BRAF mutation, microsatellite instability and the CpG island methylator phenotype. Mutations of the APC gene and p53 mutations which are characteristic non-mucinous colorectal adenocarcinoma are less common in mucinous CRC. Both physical and anti-apoptotic properties of mucin provide mechanisms for resistance to cell death. Mucin glycoproteins are associated with decreased expression of pro-apoptotic proteins, increased expression of anti-apoptotic proteins and increased cell survival signaling. The role for BCL-2 proteins, including BCL-X_L, in preventing apoptosis in mucinous CRC has been explored to a limited extent. Additional mechanisms opposing cell death include altered death receptor expression and altered mutation rates in genes responsible for chemotherapy resistance. The roles of alternate cell death programs including necroptosis and pyroptosis are not well understood in mucinous CRC. While the presence of MUC2 is associated with an immunosuppressive environment, the tumor immune environment of mucinous CRC and the role of immune-mediated tumor cell death likewise require further investigation. Improved understanding of cell death mechanisms in mucinous CRC may allow modification of currently used regimens and facilitate targeted treatment.

Adding Boost to Standard Neoadjuvant Radiation for Rectal Cancer Improves Likelihood of Complete Response

BACKGROUND

Pathologic tumor response is a prognostic factor for survival in patients with rectal cancer. Standard neoadjuvant radiation (nRT) dosing for locally advanced rectal cancer ranges from 4500 to 5400 centigray (cGy), but it is unknown if tumor regression differs as a consequence adding a boost to the tumor bed.

METHODS

The National Cancer Database (NCDB) 2006-2016 was used to identify patients 18 years of age and older with clinical stage II and III rectal cancer who received pelvic nRT dosed between 4500 and 5400 cGy. Standard nRT dose (no boost, NB) and dose with boost (DWB) were defined respectively as 4500 and 5040-5400 cGy. Complete pathologic response (pCR) was defined as postoperative pathologic stage of zero. A multivariate logistic regression was performed to evaluate the association between radiation dosing and pCR.

RESULTS

The study cohort was 28,841 patients; the majority received DWB 22,701 (78.7%), while 6140 (21.3%) received NB. pCR was achieved in 3135 (14.4%) patients. On multivariate analysis, patients who received NB were significantly less likely to have complete tumor response (OR 1.41, 95% CI 1.2-1.66, p < 0.001). Other factors significantly associated with pCR included insurance, facility type, tumor characteristics, clinical stage, and time between radiation and surgery.

CONCLUSIONS

This is the first investigation demonstrating that standard dose neoadjuvant radiation for rectal cancer was associated with a lower likelihood of pCR compared with standard dose with boost. Past studies demonstrate that rectal cancer patient survival is strongly correlated with pCR. Prospective trials should focus on examining neoadjuvant radiation dosing to evaluate if DWB improves outcomes.

Predicting poor response to neoadjuvant chemoradiotherapy for locally advanced rectal cancer: Model constructed using pre-treatment MRI features of structured report template

PURPOSE

To develop a predictive model with pre-treatment magnetic resonance imaging (MRI) findings of the structured report template and clinical parameters for poor responses prediction after neoadjuvant chemoradiotherapy (neoCRT) in locally advanced rectal cancers (LARC) patients.

METHOD

Patients with clinicopathologically confirmed LARC (training and validation datasets, n = 100 and 71, respectively) were enrolled. Patients' clinical data were retrospectively collected. MRI findings of the structured report template were analysed. The tumour regression grade (TRG) system as proposed by Mandard et al was used. Poor response was defined as TRG 3-5. Univariate logistic regression analysis and a lasso regression model were performed to select the significant predictive features from the training set. A nomogram was constructed based on a multivariable logistic regression analysis. Calibration, discrimination, and clinical usefulness of the nomogram were assessed. The calibrative and discriminative ability of our model were compared with those of models including the tumour-node-metastasis (TNM) stage and clinical factors.

RESULTS

The MRI-reported T4b stage, MRI-reported extramural venous invasion (EMVI) positivity, MRI-detected number of positive mesorectal lymph nodes (LNs) > 0, and preoperative oxaliplatin and capecitabine (CAPOX) chemotherapy regimen were incorporated into our nomogram. The nomogram showed good discrimination, with areas under the receiver operating characteristic (ROC) curves of 0·823 and 0·820 in the training and test sets, respectively, and good calibration in both datasets. The decision curve analysis confirmed that the nomogram was clinically useful. The calibrative and discriminative ability of our model were better than those models including the TNM stage and clinical factors.

CONCLUSION

A nomogram based on pre-treatment MRI features of the structured report template and clinical risk factors has potential for use as a non-invasive tool to preoperatively predict poor responses in LARC patients after neoCRT.

The impact of circumferential tumour location on the clinical outcome of rectal cancer patients managed with neoadjuvant chemoradiotherapy followed by total mesorectal excision

AIM

To investigate the impact of circumferential tumour location on neoadjuvant chemoradiotherapy (CRT) response and its prognostic value for locally advanced rectal cancer (LARC) patients after CRT and surgery.

METHODS

A retrospective study was performed on 486 patients with LARC who received neoadjuvant CRT and surgical treatment. The rate of pathological complete response (pCR) and survival among patients with anteriorly, laterally, and posteriorly located tumours were compared. Logistic regression was performed to identify pCR predictors.

RESULTS

The anterior tumours exhibited the highest pCR rate of 26.7%, which was slightly higher than the 20.0% and 12.3% for lateral and posterior tumours, respectively (P = 0.006). The 5-year Overall survival (OS) rates after CRT were similar among the anterior, lateral, and posterior groups (anterior vs lateral vs posterior: 81.1% vs 89.9% vs 84.1%, P = 0.6368). Multivariate analysis revealed that the circumferential tumour location, post-CRT serum CEA and post-CRT tumour thickness measured by MRI were independently correlated with achieving pCR.

CONCLUSION

This study is the first, to the best of our knowledge, to show that anterior LARC exhibited the highest pCR rate after neoadjuvant CRT. Patients with anterior rectal cancers do not have different prognoses from those with non-anterior cancers if they undergo neoadjuvant CRT.

Predictors of Early Distant Relapse in Rectal Cancer Patients Submitted to Preoperative Chemoradiotherapy

BACKGROUND

Neoadjuvant chemoradiotherapy (CRT) is a standard treatment for locally advanced rectal cancer. CRT leads to a better local control; however, this does not translate into a survival benefit. Long-term survival is mostly affected by the development of distant metastases after surgery. This study aimed to evaluate predictive clinical factors for the development of early metastatic disease after CRT.

METHODS

Clinical data of patients with stage II/III rectal cancer submitted to CRT between January 2000 and October 2014 were collected from prospectively maintained electronic databases of three Italian institutes. Patients were divided into two groups: those who developed metastasis within 12 months from surgical resection (Group A) and patients without or with late distant relapse (Group B).

RESULTS

Among 635 patients, 86 (13.5%) had early distant relapse within 1 year from surgery (Group A), and 549 (86.5%) did not (Group B). A higher rate of early distant relapse was associated with CEA levels above 3 ng/dL (20% vs. 10%; p <0.001), tumor lying under 5 cm from anal verge (20% vs. 9%; p <0.001), and age under 63 years (17% vs. 11%; p = 0.036). Multivariate analysis confirmed these factors to be independently correlated with a higher risk of early metastasis.

CONCLUSIONS

Younger age, low tumors, and high serum CEA may be associated with unfavorable early oncological outcomes after CRT and surgery for rectal cancer. These clinical factors could be useful to select patients for more aggressive therapeutic strategies.

Do microsatellite instability (MSI) and deficient mismatch repair (dMMR) affect the pathologic complete response (pCR) in patients with rectal cancer who received neoadjuvant treatment?

Recently, individualized approaches for the treatment of locally advanced rectal cancers (RC) have been introduced to determine the most beneficial one for boosting the tumor response and assessing the response more accurately. However, despite each patient and tumor have different molecular features, the studies at the molecular level are very limited. In this study, examining the clinical factors which are predictive of pathologic complete response (pCR), helping to determine a treatment program for the management of patients with locally advanced RC, and evaluating the relation between regression grade and MMR-MSI were aimed. 341 RC cases who had undergone surgery were included and divided into three groups according to their response to neoadjuvant treatment. The following parameters were analyzed for all patients: age at diagnosis, sex, tumor location, tumor differentiation, TNM stage, histological subtype, CEA (mean: < 5 ng/ml) level, lymphovascular-neural invasion, presence of mucinous subtype, grade, MMR, and MSI statuses. 147 patients (43.2%) had no response (group 1), 141 patients (41.3%) had an intermediate response (group 2), and 53 patients (15.5%) had a complete response (group 3). Neoadjuvant chemoradiotherapy was used in all of the patients with the same protocol. Multivariate analysis revealed that clinical T stage (p: 0.099) and MMR (p: 0.048) were the parameters which were significantly associated with pCR. Since MMR and MSI statuses were found to affect pCR, more careful patient selection for "watch and wait" protocol and further studies on molecular structures of the tumors for individualized therapies are required.

Oncologic Outcomes in Patients Who Undergo Neoadjuvant Chemoradiotherapy and Total Mesorectal Excision for Locally Advanced Rectal Cancer: A 14-Year Experience in a Single Institution

PURPOSE

This study evaluated the oncologic outcomes of locally advanced rectal cancer patients who underwent preoperative neoadjuvant chemoradiotherapy (CRT) followed by surgery and determined the prognostic significance of pathologic complete response (pCR).

METHODS

Between January 2002 and December 2015, 580 patients with rectal cancer who underwent surgery after neoadjuvant CRT were identified. Survival according to tumor response to CRT and pathologic stage was analyzed using the Kaplan-Meier method, and the Cox proportional hazard model was used to identify factors associated with survival outcomes.

RESULTS

A total of 111 patients (23.7%) achieved pCR while the other 469 patients showed residual disease. Patients with pCR had a lower pretreatment carcinoembryonic antigen level and earlier cT classification than those with residual disease. With a median follow-up of 78 months, disease-free survival (DFS) and overall survival (OS) were significantly better in the pCR group than in the residual disease group. The 5-year DFS and 5-year OS for patients with ypStage 0, I, II, or III were 92.5%, 85.1%, 72.2%, 54.3% (P < 0.001) and 94.5%, 91.0%, 83.1%, 69.3%, respectively (P < 0.001). Pathologic AJCC stage after CRT was the most statistically significant independent predictor of OS (HR, 6.97 [95% confidence interval, 3.16-15.39] for stage III vs. stage 0) and DFS (HR, 7.30 [95% confidence interval, 3.63-14.67] for stage III vs. stage 0).

CONCLUSION

Rectal cancer patients who achieved pCR showed improved survival compared to those with residual disease after preoperative CRT. Moreover, pCR was an independent indicator of OS and DFS, and pathologic AJCC stage was correlated with survival after preoperative CRT.

Predictive factors for response and toxicity after brachytherapy for rectal cancer; results from the HERBERT study

PURPOSE

The HERBERT study was a dose-finding feasibility study of a high-dose rate endorectal brachytherapy (HDREBT) boost after external beam radiotherapy (EBRT) in elderly patients with rectal cancer who were unfit for surgery. This analysis evaluates the association of patient, tumor and dosimetric parameters with tumor response and toxicity after HDREBT in definitive radiotherapy for rectal cancer.

PATIENTS AND METHODS

The HERBERT study included 38 inoperable patients with T2-3N0-1 rectal cancer. Thirteen fractions of 3 Gy EBRT were followed by three weekly HDREBT applications of 5-8 Gy per fraction. Clinical and dosimetric parameters were tested for correlation with clinical complete response (cCR), sustained partial/complete response (SR), patient reported bowel symptoms, physician reported acute and late proctitis (CTCAE v3) and endoscopically scored toxicity.

RESULTS

Thirty-five patients completed treatment and were included in the current analyses. Twenty of 33 evaluable patients achieved a cCR, the median duration of a sustained response was 32 months. Tumor volume at diagnosis showed a strong association with clinical complete response (OR 1.15; p = 0.005). No dose-response correlation was observed in this cohort. Prescribed dose to the brachytherapy CTV (D90) correlated with acute and late physician reported proctitis while CTV volume, CTV width and high dose regions in the CTV (D1cc/D2cc) were associated with endoscopic toxicity at the tumor site.

CONCLUSION

Tumor volume is the most important predictive factor for tumor response and a higher dose to the brachytherapy CTV increases the risk of severe clinically and endoscopically observed proctitis after definitive radiotherapy in elderly patients with rectal cancer.

Application of magnetic resonance diffusion kurtosis imaging for distinguishing histopathologic subtypes and grades of rectal carcinoma

Background

To evaluate the diagnostic performance of diffusion kurtosis imaging (DKI) for distinguishing different histopathological subtypes and grades of rectal carcinoma and to compare DKI with conventional diffusion-weighted imaging (DWI).

Methods

This prospective study involved 132 patients with rectal carcinoma, comprising 116 with adenocarcinoma not otherwise specified (AC) and 16 with mucinous carcinoma (MC). High spatial resolution magnetic resonance (MR) and DKI sequences (b values of 0, 600, 1000, 1500 and 2000 s/mm²) were performed for pretreatment evaluation. The mean kurtosis (MK) and mean diffusivity (MD) from DKI and the apparent diffusion coefficient (ADC) from DWI were measured by two experienced radiologists. The Mann-Whitney U test was used to evaluate different histopathological subtypes and grades. Receiver operating characteristic (ROC) curve analyses were performed to compare the diagnostic ability of different quantitative parameters.

Results

The MD and ADC values were significantly higher for MC than for AC (1.94 ± 0.51 vs. 1.33 ± 0.02 and 1.26 ± 0.64 vs. 0.92 ± 0.01, respectively; P < 0.001). The MK values were significantly lower for MC than for AC (0.66 ± 0.02 vs. 0.93 ± 0.09, P < 0.001). The MK and MD values demonstrated higher sensitivity (94%, both) and specificity (96, 93%, respectively) than the ADC values. However, all the parameters derived from both DKI and DWI showed no significant differences between different histological grades.

Conclusions

DKI is a more valuable imaging biomarker than conventional DWI for differentiating MC from AC. However, it is still debatable whether DKI is useful for distinguishing different histological grades.

Tumor regression grade as a clinically useful outcome predictor in patients with rectal cancer after preoperative chemoradiotherapy

BACKGROUND

The prognostic role of tumor regression grade is not clear. This study evaluated the prognostic significance of tumor regression grade in patients with rectal cancer after preoperative chemoradiotherapy.

METHODS

A total of 639 patients with confirmed rectal cancer who had undergone preoperative chemoradiotherapy and radical resection during the period October 2002 through December 2011 were included in this study. The tumor regression grade was graded: TRG0 (complete response), TRG1 (moderate), TRG2 (minimal), and TRG3 (poor). The prognostic significance of tumor regression grade was evaluated.

RESULTS

With a median follow-up of 56.7 months, the rates of 5-year overall survival, disease-free survival, and local recurrence-free survival among the TRG groups differed significantly (all P < .001). For patients with TRG0, TRG1, and TRG2-3, disease-free survivals were different between the ypStage (P < .001, P < .001, and P = .043). Multivariate analysis revealed findings to substantiate that the tumor regression grade represents a valuable and independent prognostic factor for long-term, disease-free survival (P = .041). Independent predictors of TRG2-3 consisted of lymphovascular invasion, tumor budding, and the pretreatment serum level of carcinoembryonic antigen in multivariate regression analysis. Clinical risk grouping, using 3 predictors for TRG2-3 was different (P < .001).

CONCLUSION

The tumor regression grade may represent a useful prognostic variable to better individualize the prognosis and potentially further therapy for each rectal cancer patient who underwent chemoradiotherapy.

The potential benefit of adjuvant chemotherapy in locally advanced rectal cancer treated with neoadjuvant chemoradiotherapy is not predicted by tumor regression grade

INTRODUCTION

Recommended treatment for locally advanced rectal cancer (LARC) is neoadjuvant chemoradiotherapy (NACRT) followed by surgery and total mesorectal excision (TME). The role of adjuvant chemotherapy (ACT) in this regimen is still debated. Assessment of Dworak's tumor regression grade (TRG) after NACRT could potentially select patients who might benefit from ACT.

MATERIALS AND METHODS

Data for patients who underwent NACRT and TME for LARC between 2007 and 2014 were retrieved from the Bordet Institute database. Overall survival (OS) and disease-free survival (DFS) were calculated for the whole population, according to whether or not they received ACT, and according to TRG.

RESULTS

We included 74 patients (38 males) with a median age of 62.7 years (33-84 years). AJCC stage cIIIb disease was the most frequent (73%). Pathologic complete response (pCR) was achieved in 13 patients (17.6%). ACT was administered to 42 patients (56.8%). Five-year OS and DFS of patients who received ACT or not were 92 and 84.5% (p = ns), and 79.9 and 84.8% (p = ns), respectively. OS was related to TRG (cut-off value of 3) (p = 0.001). ACT administration was not correlated with improved outcomes in any TRG groups.

CONCLUSION

TRG is a prognostic factor for both OS and DFS but does not appear to have a significant benefit for the selection of patients with LARC treated with NACRT who might benefit from the administration of ACT. Prospective randomized trials with larger populations are needed to identify factors that predict which patients may benefit from the administration of ACT.