Predictive clinicopathologic factors for limited response of T3 rectal cancer to combined modality therapy

Tissue-Based Markers as a Tool to Assess Response to Neoadjuvant Radiotherapy in Rectal Cancer-Systematic Review

According to current guidelines, the current treatment for locally advanced rectal cancer is neoadjuvant therapy, followed by a total mesorectal excision. However, radiosensitivity tends to differ among patients due to tumor heterogeneity, making it difficult to predict the possible outcomes of the neoadjuvant therapy. This review aims to investigate different types of tissue-based biomarkers and their capability of predicting tumor response to neoadjuvant therapy in patients with locally advanced rectal cancer. We identified 169 abstracts in NCBI PubMed, selected 48 reports considered to meet inclusion criteria and performed this systematic review. Multiple classes of molecular biomarkers, such as proteins, DNA, micro-RNA or tumor immune microenvironment, were studied as potential predictors for rectal cancer response; nonetheless, no literature to date has provided enough sufficient evidence for any of them to be introduced into clinical practice.

Pretreatment Inflammatory-Nutritional Biomarkers Predict Responses to Neoadjuvant Chemoradiotherapy and Survival in Locally Advanced Rectal Cancer

Background

To evaluate the value of pretreatment inflammatory-nutritional biomarkers in predicting responses to neoadjuvant chemoradiotherapy (nCRT) and survival in patients with locally advanced rectal cancer (LARC).

Methods

Patients with LARC who underwent nCRT and subsequent surgery between October 2012 and December 2019 were considered for inclusion. Neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), lymphocyte to monocyte ratio (LMR), and prognostic nutritional index (PNI) were calculated from according to routine laboratory data within 1 week prior to nCRT. The correlations between baseline inflammatory-nutritional biomarkers and responses were analyzed using Chi-square test or Fisher’s exact test, and multivariate logistic regression analysis was performed to identify the independent predictors of pathological responses to nCRT. Univariate and multivariate Cox proportional hazard models were used to assess the correlations of predictors with disease-free survival (DFS) and overall survival (OS).

Results

A total of 273 patients with LARC were enrolled in this study. Higher LMR and PNI were observed in the good-response group, meanwhile higher NLR and PLR were observed in the poor-response group. Multivariate logistic regression analysis results revealed that PLR and PNI independently predicted responses to nCRT. Multivariable Cox regression analysis determined that PNI was an independent predictor of DFS and OS in patients with LARC. The value of pretreatment PNI in predicting responses and survival was continuously superior to those of NLR, PLR, and LMR. The optimal cutoff value of the PNI was approximate 45. Subgroup analyses indicated that the pathological responses and survival in the high PNI group (≥ 45) were significantly better than those in the low PNI group (< 45), especially in patients with clinical stage III rectal cancer.

Conclusion

The pretreatment PNI can serve as a promising predictor of response to nCRT and survival in patients with LACR, which is superior to NLR, PLR, and LMR, and the patients with clinical stage III rectal cancer who have a higher PNI are more likely to benefit from nCRT.

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.

YKL-40/c-Met expression in rectal cancer biopsies predicts tumor regression following neoadjuvant chemoradiotherapy: a multi-institutional study

BACKGROUND

Neoadjuvant chemo-radiotherapy (CRT) followed by surgical resection is the standard treatment for locally advanced rectal cancer, although complete tumor pathological regression is achieved in only up to 30% of cases. A clinicopathological and molecular predictive stratification of patients with advanced rectal cancer is still lacking. Here, c-Met and YKL-40 have been studied as putative predictors of CRT response in rectal cancer, due to their reported involvement in chemoradioresistance in various solid tumors.

MATERIAL AND METHODS

A multicentric study was designed to assess the role of c-Met and YKL-40 expression in predicting chemoradioresistance and to correlate clinical and pathological features with CRT response. Immunohistochemistry and fluorescent in situ hybridization for c-Met were performed on 81 rectal cancer biopsies from patients with locally advanced rectal adenocarcinoma. All patients underwent standard (50.4 gy in 28 fractions + concurrent capecitabine 825 mg/m2) neoadjuvant CRT or the XELOXART protocol. CRT response was documented on surgical resection specimens and recorded as tumor regression grade (TRG) according to the Mandard criteria.

RESULTS

A significant correlation between c-Met and YKL-40 expression was observed (R = 0.43). The expressions of c-Met and YKL-40 were both significantly associated with a lack of complete response (86% and 87% of c-Met and YKL-40 positive cases, p< 0.01 and p = 0.006, respectively). Thirty of the 32 biopsies co-expressing both markers had partial or absent tumor response (TRG 2-5), strengthening their positive predictive value (94%). The exclusive predictive role of YKL-40 and c-Met was confirmed using a multivariate analysis (p = 0.004 and p = 0.007 for YKL-40 and c-Met, respectively). TRG was the sole morphological parameter associated with poor outcome.

CONCLUSION

c-Met and YKL-40 expression is a reliable predictor of partial/absent response to neoadjuvant CRT in rectal cancer. Targeted therapy protocols could take advantage of prior evaluations of c-MET and YKL-40 expression levels to increase therapeutic efficacy.

Response to neoadjuvant therapy in patients with early age-of-onset rectal cancer

BACKGROUND

The incidence of rectal cancer in patients ≤ 50 years of age is increasing. The response to neoadjuvant treatment in patients ≤ 50 years of age is not known. Factors affecting the response to neoadjuvant therapy in this age group have not been evaluated.

OBJECTIVE

This study aims to evaluate the rate and identify factors that affect pathologic response to neoadjuvant therapy in patients with early age-of-onset rectal cancer.

DESIGN

This study is a retrospective review.

SETTING

The investigation was conducted at a tertiary-care cancer referral center.

PATIENTS

Included were 193 consecutive patients ≤ 50 years of age with rectal cancer who underwent neoadjuvant therapy followed by surgical resection.

INTERVENTIONS

No interventions were performed.

MAIN OUTCOME MEASURES

The primary outcome measured was the pathologic response to neoadjuvant treatment.

RESULTS

The median age was 44 years, and 34% of the patients were female. The median distance from the anal verge was 7 cm. The median percentage of lumen occupied by tumor was 50%. The median CEA level was 3.5 ng/mL. The median treatment response was 80%. The mean number of lymph nodes examined was 15 per patient. Twenty-two percent of patients had a complete or near-complete (≥ 95%) response to neoadjuvant treatment. Seventy-seven percent of evaluable patients experienced tumor or lymph node downstaging on pathologic examination. The presence of adverse histologic features, percentage of lumen occupied by tumor, and CEA level differed between those with <95% response and those with ≥ 95% response to neoadjuvant therapy, although CEA level was not significant when stage IV patients were excluded.

LIMITATIONS

This is a retrospective review with heterogeneity in workup, treatment regimens, and interval to surgery. Long-term oncologic outcomes are not available.

CONCLUSIONS

The rate of response to neoadjuvant treatment appears similar in patients with early age-of-onset rectal cancer to non-age-based cohorts in the literature. Adverse histologic features and bulky circumferential tumors may be suggestive of a decreased response to neoadjuvant therapy.

Treatment of locally advanced rectal cancer: Controversies and questions

Rectal cancers extending through the rectal wall, or involving locoregional lymph nodes (T3/4 or N1/2), have been more difficult to cure. The confines of the bony pelvis and the necessity of preserving the autonomic nerves makes surgical extirpation challenging, which accounts for the high rates of local and distant relapse in this setting. Combined multimodality treatment for rectal cancer stage II and III was recommended from National Institute of Health consensus. Neoadjuvant chemoradiation using fluoropyrimidine-based regimen prior to surgical resection has emerged as the standard of care in the United States. Optimal time of surgery after neoadjuvant treatment remained unclear and prospective randomized controlled trial is ongoing. Traditionally, 6-8 wk waiting period was commonly used. The accuracy of studies attempting to determine tumor complete response remains problematic. Currently, surgery remains the standard of care for rectal cancer patients following neoadjuvant chemoradiation, whereas observational management is still investigational. In this article, we outline trends and controversies associated with optimal pre-treatment staging, neoadjuvant therapies, surgery, and adjuvant therapy.

Improvement in T-staging of rectal carcinoma: using a novel endorectal ultrasonography technique with sterile coupling gel filling the rectum

Our purpose was to study the accuracy of using endorectal ultrasonography (ERUS) with sterile coupling gels filling the rectum in the preoperative T-staging of rectal carcinoma. A total of 189 patients with confirmed rectal carcinoma were recruited. All underwent ERUS and surgery within the week following sonography. EURS was performed by introducing sterile coupling gel into the rectum. Two radiologists looked at the images at the same time and agreed upon staging. Rectal carcinoma was staged from Tis to T4. The accuracy of T-staging by ERUS was 89.95%. The sensitivity, specificity, PPV and NPV for ERUS at different stages were calculated. For early stage (Tis and T1), these values were 93.62%, 97.89%, 93.62% and 97.89%, respectively. ERUS filling with sterile coupling gel in the rectum overcomes the pressure effect from a water bath and the restriction caused by tumor stenosis, thus, greatly improving the accuracy of T-staging. The examination is real-time, safe and inexpensive.

Combination of differentiation and T stage can predict unresponsiveness to neoadjuvant therapy for rectal cancer

AIM

The study aimed to identify the factors predictive for extreme unresponsiveness to neoadjuvant therapy for rectal cancer.

METHOD

Ninety-six patients with rectal cancer received neoadjuvant therapy (41 were treated with radiotherapy and 55 with chemoradiotherapy) before surgery. Tumour response, downstaging, pathological complete response (pCR) and disease-free survival were evaluated.

RESULTS

Tumour response, downstaging and pCR occurred in 70 (72.9%), 47 (49.0%) and 14 (14.6%) patients, respectively. Univariate analyses showed that a large tumour size, T4 stage, elevated serum tumour markers, poor differentiation, radiotherapy alone and mucinous tumour were indicators of poor tumour response and/or downstaging. On multivariate analysis, chemoradiotherapy was found to be predictive for tumour response and downstaging, whereas mucinous type and T4 stage negatively affected tumour response. No variable was found to be associated with pCR, but poor differentiation and T4 stage together predicted extreme unresponsiveness with a high specificity and a high positive predictive value. Very poor disease-free survival was also observed in patients simultaneously carrying these phenotypes.

CONCLUSION

Neoadjuvant chemoradiotherapy is superior to radiotherapy alone in producing a response of rectal cancer. Unresponsiveness was most likely to occur in patients with poor differentiation and T4 disease.

Oncologic outcomes of primary and post-irradiated early stage rectal cancer: A retrospective cohort study

AIM: To evaluate the oncologic outcomes of primary and post-irradiated early stage rectal cancer and the effectiveness of adjuvant chemotherapy for rectal cancer patients.

METHODS: Eighty-four patients with stage I rectal cancer after radical surgery were studied retrospectively and divided into ypstage I group (n = 45) and pstage I group (n = 39), according to their preoperative radiation, and compared by univariate and multivariate analysis.

RESULTS: The median follow-up time of patients was 70 mo. No significant difference was observed in disease progression between the two groups. The 5-year disease-free survival rate was 84.4% and 92.3%, respectively (P = 0.327) and the 5-year overall survival rate was 88.9% and 92.3%, respectively, for the two groups (P = 0.692). The disease progression was not significantly associated with the pretreatment clinical stage in ypstage I group. The 5-year disease progression rate was 10.5% and 19.2%, respectively, for the patients who received adjuvant chemotherapy and for those who rejected chemotherapy in the ypstage I group (P = 0.681).

CONCLUSION: The oncologic outcomes of primary and post-irradiated early stage rectal cancer are similar. Patients with ypstage I rectal cancer may slightly benefit from adjuvant chemotherapy.

A systematic review of cancer related patient outcomes after anterior resection and abdominoperineal excision for rectal cancer in the total mesorectal excision era

PURPOSE

It is a widely held view that anterior resection (AR) for rectal cancer is an oncologically superior operation to abdominoperineal excision (APE). However, some centres have demonstrated better outcomes with APE. We conducted a systematic review of high-quality studies within the total mesorectal excision (TME) era comparing outcomes of AR and APE.

METHODS

A literature search was performed to identify studies within the TME era comparing AR and APE with regard to the following: circumferential resection margin (CRM) status, tumour perforation rates, specimen quality, local recurrence, overall survival (OS; 3 or 5 year), cancer-specific survival (CSS) and disease-free survival (DFS). Additional data regarding patient demographics and tumour characteristics was collected.

RESULTS

Twenty four studies fulfilled the eligibility criteria with Newcastle-Ottawa scores of six or greater. Where a significant difference was found, all studies reported lower and more advanced tumours for APE and 4/5 studies observed more frequent use of neoadjuvant and adjuvant therapies in APE patients. Tumour perforation rates and CRM involvement where reported, were significantly greater for APE. 8 out of 10 studies showing significant differences in local recurrence reported higher rates for APE but no differences were observed with distant recurrence. Where differences were noted, AR was reported to have increased DFS, CSS and OS compared to APE.

CONCLUSIONS

Patients treated with AR have lower rates of tumour perforation and CRM involvement and tend to have better outcomes with regard to disease recurrence and survival. However, tumours treated by APE are lower and more locally advanced.

Prognostic value of tumor response to neoadjuvant therapy in rectal carcinoma

BACKGROUND

Neoadjuvant treatment in the multimodal therapy concept of rectal carcinoma has considerable effects on prognosis appraisal.

OBJECTIVE

This study aimed to evaluate the tumor response specified as an improvement by at least one stage defined in terms of the International Union Against Cancer stages as a prognostic factor.

DESIGN

This investigation was designed as a prospective cohort study.

SETTING

This study was performed at a community-based hospital with a specialized colorectal unit.

PATIENTS

One hundred seventy-four patients with locally advanced rectal carcinoma, treated in the Dresden-Friedrichstadt hospital from 1997 to 2009, who received long-term preoperative chemoradiotherapy and underwent curative resection, were included in this study.

MAIN OUTCOME MEASURES

The main outcome measures were cause-specific and disease-free survival with respect to T and N category, International Union Against Cancer stage, venous and lymphatic invasions, grading, CEA level, complete pathologic response, tumor regression grading, International Union Against Cancer stage shift, T, N, and CEA shift, types of neoadjuvant therapy, adjuvant therapy, interval between completion of neoadjuvant chemoradiotherapy and surgery, and number of extracted lymph nodes in resected specimens. Univariate and multivariate analyses were performed.

RESULTS

Median follow-up was 45 months. One hundred twenty-one patients (69.5%) showed a response to the treatment, whereas 53 (30.5%) did not. Five-year cause-specific and disease-free survival for responders (n = 121) vs nonresponders (n = 53) were 92.6% and 73.7% vs 84.9% and 47.9%. In the univariate analysis, ypN category, venous and lymphatic invasion, tumor regression grading, International Union Against Cancer stage shift, and T and N shift were significantly predictive for cause-specific and disease-free survival. Furthermore, ypUICC stage, ypT category, grading, and complete pathologic response had an impact on disease-free survival. In the multivariate analysis, only the International Union Against Cancer stage shift kept its independent explanatory power for cause-specific P = .012, HR 3.10 (95% CI 1.28-7.51) and disease-free survival P < .001, HR 3.85 (95% CI 1.98-7.51).

LIMITATIONS

The determination of International Union Against Cancer stage shift depends on the pretreatment staging modalities.

CONCLUSION

Our investigation demonstrates that the response of tumor to neoadjuvant therapy is an independent prognostic factor in patients with rectal carcinoma.

Pretreatment transcriptional profiling for predicting response to neoadjuvant chemoradiotherapy in rectal adenocarcinoma

PURPOSE

Patients presenting with locally advanced rectal cancer currently receive preoperative radiotherapy with or without chemotherapy. Although pathologic complete response is achieved for approximately 10% to 30% of patients, a proportion of patients derive no benefit from this therapy while being exposed to toxic side effects of treatment. Therefore, there is a strong need to identify patients who are unlikely to benefit from neoadjuvant therapy to help direct them toward alternate and ultimately more successful treatment options.

EXPERIMENTAL DESIGN

In this study, we obtained expression profiles from pretreatment biopsies for 51 rectal cancer patients. All patients underwent preoperative chemoradiotherapy, followed by resection of the tumor 6 to 8 weeks posttreatment. Gene expression and response to treatment were correlated, and a supervised learning algorithm was used to generate an original predictive classifier and validate previously published classifiers.

RESULTS

Novel predictive classifiers based on Mandard's tumor regression grade, metabolic response, TNM (tumor node metastasis) downstaging, and normal tissue expression profiles were generated. Because there were only 7 patients who had minimal treatment response (>80% residual tumor), expression profiles were used to predict good tumor response and outcome. These classifiers peaked at 82% sensitivity and 89% specificity; however, classifiers with the highest sensitivity had poor specificity, and vice versa. Validation of predictive classifiers from previously published reports was attempted using this cohort; however, sensitivity and specificity ranged from 21% to 70%.

CONCLUSIONS

These results show that the clinical utility of microarrays in predictive medicine is not yet within reach for rectal cancer and alternatives to microarrays should be considered for predictive studies in rectal adenocarcinoma.

Using gene expression profiling to predict response and prognosis in gastrointestinal cancers-the promise and the perils

Cancer treatment is now moving toward a personalized approach, promising improved rates of response and survival. A number of studies have employed the use of microarrays to investigate the predictive potential of expression profiling in gastrointestinal (GI) cancer patients. However while many robust predictive classifiers relating to response and prognosis have been generated for GI cancer patients, these have yet to make the transition to the clinic. The main obstacle is the limited cross validation between predictive gene lists identified for the same tumor type and outcome. Differences in the experimental design, analysis, and interpretation of results all contribute to this variation, with numerous factors influencing which genes are highlighted as predictive. While predictive genomics shows immense potential, it is still a relatively new field and the validation of predictive gene lists derived from microarray data remains a challenge. Future studies must carefully consider all aspects of experimental design to ensure a clinically applicable predictive test can be developed. With this in mind, more extensive and collaborative research must be undertaken before microarray-based platforms can be used routinely in tailoring GI cancer treatment and change clinical practice. Larger cohorts and consistency in methodology will enable the findings from this research to make the transition to the clinic.

Predictive factors of tumor response after neoadjuvant chemoradiation for locally advanced rectal cancer

PURPOSE

Neoadjuvant chemoradiation followed by surgery is the standard of care for locally advanced rectal cancer. The aim of this study was to correlate tumor response to survival and to identify predictive factors for tumor response after chemoradiation.

METHODS AND MATERIALS

From 1998 to 2008, 168 patients with histologically proven locally advanced adenocarcinoma treated by preoperative chemoradiation before total mesorectal excision were retrospectively studied. They received a radiation dose of 45 Gy with a concomitant 5-fluorouracil (5-FU)-based chemotherapy. Analysis of tumor response was based on lowering of the T stage between pretreatment endorectal ultrasound and pathologic specimens. Overall and progression-free survival rates were correlated with tumor response. Tumor response was analyzed with predictive factors.

RESULTS

The median follow-up was 34 months. Five-year disease-free survival and overall survival rates were, of 44.4% and 74.5% in the whole population, 83.4% and 83.4%, respectively, in patients with pathological complete response, 38.6% and 71.9%, respectively, in patients with tumor downstaging, and 29.1 and 58.9% respectively, in patients with absence of response. A pretreatment carcinoembryonic antigen (CEA) level of <5 ng/ml was significantly independently associated with pathologic complete tumor response (p = 0.019). Pretreatment small tumor size (p = 0.04), pretreatment CEA level of <5 ng/ml (p = 0.008), and chemotherapy with capecitabine (vs. 5-FU) (p = 0.04) were significantly associated with tumor downstaging.

CONCLUSIONS

Downstaging and complete response after CRT improved progression-free survival and overall survival of locally advanced rectal adenocarcinoma. In multivariate analysis, a pretreatment CEA level of <5 ng/ml was associated with complete tumor response. Thus, small tumor size, a pretreatment CEA level of < 5 ng/ml, and use of capecitabine were associated with tumor downstaging.

Endosonographic staging of lower intestinal malignancy

The use of EUS in the assessment of rectal pathology is well established. The accurate staging of lower intestinal tumours predicts prognosis and guides the planning of individual patient treatment. Increased experience and the development of high resolution three-dimensional EUS has lead to the greater accuracy of rectal staging with EUS of rectal tumours now considered the gold standard showing T stage accuracy that ranges from 75% to 95%, with N stage accuracy ranging from 65% to 80%. The use of EUS in the staging of colonic pathology, however, is not so well established though advances in miniprobe EUS has improved the assessment of colonic tumours. EUS is also of benefit in the assessment of anal pathology though here, accurate correlation with histology has not been firmly established.

Sphincter preservation in low rectal cancer is facilitated by preoperative chemoradiation and intersphincteric dissection

OBJECTIVE

The aim of this study was to evaluate oncologic outcome in patients with locally advanced distal rectal cancer treated with preoperative chemoradiation followed by low anterior resection (LAR)/stapled coloanal anastomosis, LAR/intersphincteric dissection/hand-sewn coloanal anastomosis, or abdominoperineal resection (APR).

SUMMARY BACKGROUND DATA

Distal rectal cancer presents a surgical challenge, and the goals of treatment often include tumor eradication without sacrifice of the anal sphincters. The technique of intersphincteric resection removes the internal anal sphincter to gain additional distal rectal margin in hopes of avoiding a permanent stoma.

METHODS

We analyzed 148 patients with stage II and III rectal cancers (endorectal ultrasound staged uT3-4 and/or uN1) located < or =6 cm from the anal verge, treated by preoperative chemoradiation and total mesorectal excision from 1998 to 2004. Eighty-five patients (57%) had sphincter-preserving resection (41, LAR/stapled coloanal anastomosis; 44, LAR/intersphincteric resection/hand-sewn coloanal anastomosis); 63 patients had APR.

RESULTS

Patients undergoing APR were older, with more poorly differentiated tumors evidencing less response to chemoradiation and more likely to require extended resection. Complete resection with negative histologic margins was achieved in 92%; circumferential margins were positive in 2 (5%) of 44 in the intersphincteric resection group and 8 (13%) of 63 in the APR group. Distal margins were positive in 2 (5%) of 44 in the intersphincteric resection group. With median follow-up of 47 months, there were a total of 7 local recurrences (5%): 1, 0, and 6 in the stapled anastomosis, intersphincteric resection, and APR groups, respectively. Estimated 5-year recurrence-free survival for the stapled anastomosis, intersphincteric resection, and APR groups were 85%, 83%, and 47% respectively (P = 0.001).

CONCLUSIONS

In low rectal cancer, sphincter preservation is facilitated by a significant response to preoperative chemoradiation and intersphincteric resection, without compromise of margins or outcome. In those who have a less favorable response, abdominoperineal resection is more likely to be required and is associated with poorer outcome.

Pathologic stage is most prognostic of disease-free survival in locally advanced rectal cancer patients after preoperative chemoradiation

BACKGROUND

Preoperative chemoradiation is the standard treatment for locally advanced rectal cancer. However, it is uncertain whether pretreatment clinical stage, degree of response to neoadjuvant treatment, or pathologic stage is the most reliable predictor of outcome. This study compared various staging elements and treatment-related variables to identify which factors or combination of factors reliably prognosticates disease-free survival in rectal cancer patients receiving neoadjuvant combined modality therapy.

METHODS

From a prospectively maintained single institution database, 342 consecutive patients with locally advanced rectal cancer staged by endorectal ultrasound were identified. Patients underwent rectal resection 4 to 8 weeks after a 5.5-week course of pelvic radiotherapy/concurrent chemotherapy. The degree of tumor regression was histologically graded on each resected specimen using a previously reported response scale of 0% to 100%. Predictive models of disease-free survival were created utilizing available pretherapy and postoperative staging elements in addition to the degree of tumor regression noted histologically. Model accuracy was measured and compared by concordance index, with 95% confidence interval (CI).

RESULTS

Stratifying patients by degree of tumor regression predicted outcome with a concordance index of 0.65 (95% CI, 0.59-0.71), which was significantly better than models using preoperative stage elements (concordance index of 0.54; 95% CI, 0.50-0.58). However, the model found to be most predictive of disease-free survival stratified patients by final pathologic T classification and N classification elements, with a concordance index of 0.75 (95% CI, 0.70-0.80).

CONCLUSIONS

Tumor response to preoperative therapy is a strong predictor of disease-free survival. However, outcome is most accurately estimated by final pathologic stage, which is influenced by both preoperative stage and response to therapy.