Complete pathologic response after combined modality treatment for rectal cancer and long-term survival: a meta-analysis

Comprehensive evaluation of the effectiveness of gene expression signatures to predict complete response to neoadjuvant chemoradiotherapy and guide surgical intervention in rectal cancer

Neoadjuvant chemoradiotherapy (nCRT) may lead to complete tumor regression in rectal cancer patients. Prediction of complete response to nCRT may allow a personalized management of rectal cancer and spare patients from unnecessary radical total mesorectal excision with or without sphincter preservation. To identify a gene expression signature capable of predicting complete pathological response (pCR) to nCRT, we performed a gene expression analysis in 25 pretreatment biopsies from patients who underwent 5FU-based nCRT using RNA-Seq. A supervised learning algorithm was used to identify expression signatures capable of predicting pCR, and the predictive value of these signatures was validated using independent samples. We also evaluated the utility of previously published signatures in predicting complete response in our cohort. We identified 27 differentially expressed genes between patients with pCR and patients with incomplete responses to nCRT. Predictive gene signatures using subsets of these 27 differentially expressed genes peaked at 81.8% accuracy. However, signatures with the highest sensitivity showed poor specificity, and vice-versa, when applied in an independent set of patients. Testing previously published signatures on our cohort also showed poor predictive value. Our results indicate that currently available predictive signatures are highly dependent on the sample set from which they are derived, and their accuracy is not superior to current imaging and clinical parameters used to assess response to nCRT and guide surgical intervention.

Pathologic processing of the total mesorectal excision

Total mesorectal excision (TME) is the current optimal surgical treatment for patients with rectal carcinoma. A complete TME is related to lower local recurrence rates and increased patient survival. Many confounding factors in the patient's anatomy and prior therapy can make it difficult to obtain a perfect plane, and thus a complete TME. The resection specimen can be thoroughly evaluated, grossly and microscopically, to identify substandard surgical outcomes and increased risk of local recurrence. Complete and accurate data reporting is critical for patient care and helps surgeons improve their technique.

RandomizEd controlled trial for pre-operAtive dose-escaLation BOOST in locally advanced rectal cancer (RECTAL BOOST study): study protocol for a randomized controlled trial

Background

Treatment for locally advanced rectal cancer (LARC) consists of chemoradiation therapy (CRT) and surgery. Approximately 15% of patients show a pathological complete response (pCR). Increased pCR-rates can be achieved through dose escalation, thereby increasing the number patients eligible for organ-preservation to improve quality of life (QoL). A randomized comparison of 65 versus 50Gy with external-beam radiation alone has not yet been performed. This trial investigates pCR rate, clinical response, toxicity, QoL and (disease-free) survival in LARC patients treated with 65Gy (boost + chemoradiation) compared with 50Gy standard chemoradiation (sCRT).

Methods/design

This study follows the ‘cohort multiple randomized controlled trial’ (cmRCT) design: rectal cancer patients are included in a prospective cohort that registers clinical baseline, follow-up, survival and QoL data. At enrollment, patients are asked consent to offer them experimental interventions in the future. Eligible patients—histologically confirmed LARC (T3NxM0 <1 mm from mesorectal fascia, T4NxM0 or TxN2M0) located ≤10 cm from the anorectal transition who provided consent for experimental intervention offers—form a subcohort (n = 120). From this subcohort, a random sample is offered the boost prior to sCRT (n = 60), which they may accept or refuse. Informed consent is signed only after acceptance of the boost. Non-selected patients in the subcohort (n = 60) undergo sCRT alone and are not notified that they participate in the control arm until the trial is completed.

sCRT consists of 50Gy (25 × 2Gy) with concomitant capecitabine. The boost (without chemotherapy) is given prior to sCRT and consists of 15 Gy (5 × 3Gy) delivered to the gross tumor volume (GTV). The primary endpoint is pCR (TRG 1). Secondary endpoints include acute grade 3–4 toxicity, good pathologic response (TRG 1-2), clinical response, surgical complications, QoL and (disease-free) survival. Data is analyzed by intention to treat.

Discussion

The boost is delivered prior to sCRT so that GTV adjustment for tumor shrinkage during sCRT is not necessary. Small margins also aim to limit irradiation of healthy tissue. The cmRCT design provides opportunity to overcome common shortcomings of classic RCTs, such as slow recruitment, disappointment-bias in control arm patients and poor generalizability.

Trial registration

The Netherlands Trials Register NL46051.041.13. Registered 22 August 2013. ClinicalTrials.gov NCT01951521. Registered 18 September 2013.

Baseline neutrophil-lymphocyte ratio (≥2.8) as a prognostic factor for patients with locally advanced rectal cancer undergoing neoadjuvant chemoradiation

Background

The neutrophil-lymphocyte ratio (NLR) has been proposed as an indicator of systemic inflammatory response and may predict the clinical outcome in some cancers, such as head and neck cancer and gastric cancer. However, the value of this ratio is variable in different cancers. Studies of the relationship between NLR and both survival and response to chemoradiation have been limited with respect to locally advanced rectal cancer.

Methods and materials

From 2006 to 2011, 199 consecutive locally advanced rectal cancer patients who were treated with neoadjuvant chemoradiation in the Shanghai Cancer Center were enrolled and analysed retrospectively. Tumor response was evaluated by pathological findings. The baseline total white blood cell count (WBC) and the neutrophil, lymphocyte, platelet counts were recorded. The neutrophil-lymphocyte ratio (NLR) and the relationship with clinical outcomes such as overall survival (OS) and disease-free survival (DFS) was analyzed.

Results

With ROC analysis, the baseline NLR value was found to significantly predict prognosis in terms of OS well in locally advanced rectal cancer patients. A multivariate analysis identified that a cut-off value of NLR ≥ 2.8 could be used as an independent factor to indicate decreased OS (HR, 2.123; 95% CI, 1.140-3.954; P = 0.018). NLR ≥ 2.8 was also associated with worse DFS in univariate analysis (HR, 1.662; 95% CI, 1.037-2.664; P = 0.035), though it was not significant in the multivariate analysis (HR, 1.363; 95% CI, 0.840-2.214; P = 0.210). There was no observed significant correlation of mean value of NLR to the response to neoadjuvant chemoradiation. The mean NLR in the ypT0-2 N0 group was 2.68 ± 1.38, and it was 2.77 ± 1.38 in the ypT3-4/N+ group, with no statistical significance (P = 0.703). The mean NLR in the TRG 0–1 group was 2.68 ± 1.42, and it was 2.82 ± 1.33 in the TRG 2–3 group with no statistical significance (P = 0.873).

Conclusions

An elevated baseline NLR is a valuable and easily available prognostic factor for OS in addition to tumor response after neoadjuvant therapy. Baseline NLR could be a useful candidate factor for stratifying patients and making treatment decisions in locally advanced rectal cancer.

Prognostic role and predictors of complete pathologic response to neoadjuvant chemotherapy in primary unresectable ovarian cancer

OBJECTIVE

The objective of the study was to analyze in a large series of unresectable advanced ovarian cancer (AOC) patients the prognostic role of pathological response to neoadjuvant chemotherapy (NACT).

STUDY DESIGN

We retrospectively evaluated 322 unresectable AOC patients treated with NACT followed by interval debulking surgery (IDS). Pathological response was classified as follows: complete (cPR) in the absence of residual disease, microscopic (microPR) in the presence of microscopic tumor foci (maximum diameter ≤3 mm), and macroscopic (macroPR) when macroscopic residual disease was detected.

RESULTS

cPR was observed in 21 (6.5%), microPR in 104 (32.3%), and macroPR in 197 (61.2%) patients. No differences were observed in the distribution of baseline clinicopathological characteristics between the groups. Median progression-free survival was 36 months in cPR, 16 in microPR, and 13 in macroPR (P = .001). Median overall survival was 72 months in cPR, 38 in microPR, and 29 in macroPR (P = .018). The survival differences between microPR and macroPR patients were not confirmed when the analysis included only cases resected to no gross residual disease at IDS. cPR retained the independent prognostic role in the multivariate analysis. International Federation of Gynecology and Obstetrics stage IV was the only negative independent predictor of cPR (χ(2) = 5.362, P = .021).

CONCLUSION

cPR is an uncommon event in AOC patients receiving NACT and is associated with a longer progression-free survival and overall survival compared with women showing no cPR, even in patients receiving IDS with no gross residual disease. The proposed classification of pathological response may serve in the next future as an easily assessable and highly valuable prognostic tool in this clinical setting.

Mutational and clinical predictors of pathologic complete response in the treatment of locally advanced rectal cancer

PURPOSE

Preoperative chemoradiation (CRT) for locally advanced rectal adenocarcinoma achieves pathologic complete response (pCR) in 8-20% of patients. Mutations in critical cancer genes may contribute to lack of pCR. We retrospectively evaluated our institutional experience to determine potential mutational and clinical predictors of pCR in patients treated with CRT.

METHODS

Patients with locally advanced rectal adenocarcinoma treated with preoperative CRT (n = 79) were identified. A clinical cancer genotyping assay evaluated 140 hotspot mutation sites across 15 cancer genes in 47 patients with sufficient tissue. Mutational profiles were compared in pre- and post-CRT specimens and with pCR rate. Clinical variables were evaluated using logistic regression.

RESULTS

Genotyping identified mutations in KRAS (43%), APC (17%), BRAF (4%), NRAS (4%), PIK3CA (4%), and TP53 (11%). In the entire cohort, 21.5% had a pCR. No patients with BRAF, NRAS, APC, or TP53 achieved a pCR. pCR rate was 23.5% (4/17) in wild-type tumors versus 3.3% (1/30) in those with a mutation. There was no difference in the mutation rates in pre- versus post-CRT specimens. On univariate analysis, clinical predictors of pCR included post-RT carcinoembriogenic antigen level of ≤2.5 and smaller tumor size. No patients with a pCR developed recurrence.

CONCLUSION

Patients without mutations in commonly mutated cancer genes may be associated with a higher likelihood of having a pCR after preoperative CRT. This should be confirmed in a prospective study.

Impact of interval between preoperative chemotherapy and surgery on therapeutic effects in patients with stage ⅢA and ⅢB rectal cancer

AIM: To assess whether the time interval between neoadjuvant chemoradiotherapy and surgery affects the pathologic complete response (pCR) rate, disease-free survival (DFS), disease recurrence and overall survival (OS) in patients with stage ⅢA and ⅢB rectal cancer.

METHODS: We retrospectively studied 93 patients diagnosed with stage ⅢA and ⅢB rectal cancer by pathological examination who underwent neoadjuvant therapy followed by total mesorectal excision (TME) between March 2009 and March 2011 at our hospital. They were divided into two groups according to the interval between neoadjuvant therapy and surgery: A (≤7 wk, n = 49) and B (>7 wk, n = 44). The primary endpoints were reported as pCR rate, DFS, disease recurrence and OS. Secondary endpoints were type of surgery, postoperative complications, operative time and length of hospital stay.

RESULTS: The overall pCR rate was 10.75% (pCR: group A vs group B, 8.2% vs 13.6%; P = 0.027), and the overall 3-year DFS was 39.8% (DFS: group A vs group B, 28.6% vs 52.3%; P = 0.013). Disease recurrence was 20.4% in group A vs 4.5% in group B (P = 0.023). There were no significant differences in OS, type of surgery, postoperative complications, operative time or length of hospital stay between the two groups.

CONCLUSION: A neoadjuvant-surgery interval > 7 wk increases the rates of pCR and DFS and decreases disease recurrence in patients with stage ⅢA and ⅢB rectal cancer, with no effect on type of surgery, postoperative complications, operative time, length of hospital stay or oncologic outcome.

Does the addition of targeted biological agents to first-line chemotherapy for advanced colorectal cancer increase complete response? A systematic review and meta-analysis

AIM

The study assessed whether the addition of monoclonal antibodies (MoAbs) to first-line chemotherapy for advanced colorectal cancer (CRC) increases the complete response (CR) compared with controls.

METHOD

PubMed was reviewed for randomized clinical trials (RCTs) with approved MoAbs (bevacizumab, cetuximab and panitumumab) vs non-MoAbs as first-line therapy for patients with advanced CRC. The incidence and ratio of CR events were calculated in patients assigned to MoAbs compared with controls.

RESULTS

A total of 3790 patients from nine RCTs were included for analysis. The overall incidence of CR in patients treated with MoAbs was 2.4% (95% CI: 1.7-3.3%) compared with 1.3% (95% CI: 0.8-2.2%) in controls. Comparison of the different types of MoAbs showed that the incidence of CR was higher for bevacizumab (3.1%, 95% CI: 2.1-4.3%) than for cetuximab (0.8%, 95% CI: 0.4-1.8%). The addition of MoAbs to chemotherapy significantly increased the OR of obtaining a CR compared with controls (OR = 1.96; 95% CI: 1.12-3.46; P = 0.02). No significant differences in the OR were observed in any of the subgroups.

CONCLUSION

The CR is a rare event in advanced CRC; however, the addition of MoAbs to first-line chemotherapy significantly increases the curative rate of metastatic disease compared with controls.

Neoadjuvant chemoradiation with concomitant boost radiotherapy associated to capecitabine in rectal cancer patients

PURPOSE

The primary end-points were complete pathological response and local control. Secondary end-points were survivals, anal sphincter preservation, and toxicity profile.

METHODS

Patients with T3/T4 and or N+ rectal cancer (n = 65) were treated with preoperative concomitant boost radiotherapy (55 Gy/25 fractions) associated to concurrent chemotherapy with oral capecitabine.

RESULTS

All patients completed the programmed treatment. The complete pathological response was achieved by 17 % of the patients. Anal sphincter preservation surgery was possible for 86 % of the patients with low rectal cancer (≤ 5 cm from the anal verge). The T-stage and N-stage downstaging were achieved by 40 and 58 % of the patients, respectively. Circumferential radial margin was involved (close/positive) in eight patients. After a median follow-up of 26 months, local and distant recurrence occurred in two and 11 patients, respectively. The 3-year overall survival and disease-free survival were 86.8 and 81 %, respectively. Non-hematological ≥ grade 3 toxicities were observed in 15 % of the patients. On univariate analysis N-downstaging and positive circumferential radial margin were significantly associated with worse overall survival (p = 0.003 and p = 0.023, respectively), disease-free survival (p = 0.001 and p = 0.036, respectively), and metastasis-free survival (MFS) (p = 0.001 and p = 0.038, respectively).On multivariate analysis, the N-downstaging were significantly associated with better overall survival (OS) (p = 0.022).

CONCLUSIONS

Our data support the efficacy of preoperative treatment for rectal cancer in terms of local outcomes. Radiation treatment intensification may have a biological rationale; longer follow-up is needed.

Interval between neoadjuvant treatment and definitive surgery in locally advanced rectal cancer: impact on response and oncologic outcomes

PURPOSE

The optimal waiting period between neoadjuvant treatment completion and surgery in locally advanced rectal cancer (LARC) is controversial. The specific purpose of this study was to evaluate the effect of prolonging this interval on the pathologic response, postoperative morbidity, and long-term oncologic outcomes.

METHODS

Retrospective data analysis is reported from LARC patients who had been treated with chemoradiation followed by surgery and intra-operative radiotherapy, between February 1995 and December 2012. In total, two groups were studied, according to the time elapsed between neoadjuvant treatment and surgery: conventional interval (CI; <6 weeks) and delayed interval (DI; ≥6 weeks). Clinicopathological data related to tumor response, postoperative morbidity, and oncologic outcomes were compared.

RESULTS

This study included 335 consecutive LARC patients. There was a higher proportion of patients with clinical staging nodal involvement (cN+) in the DI group (76.6 vs. 64.1 %; p = 0.01). The pathologic complete response (pCR) was not significantly different among groups (8.8 vs. 12.1 %; p = 0.34). Longer intervals did not affect complication incidence or severity or hospital admission length. Certain postneoadjuvant tumor effect parameters were significantly increased in the DI group, including N-downstaging and T-downsizing. After a median follow-up of 71 months, patients in the DI group presented with superior 5-year overall survival (OS) (55.9 vs. 70.4 %, p = 0.014); however, no statistically significant differences were observed in 5-year disease-free survival (DFS) or 5-year local control (LC) (69.9 vs. 74.9 %, p = 0.223; 90.4 vs. 94.5 %, p = 0.123, respectively).

CONCLUSIONS

A modest surgical interval delay (≥6 weeks) did not increase postoperative complications and was identified as a favorable prognostic factor for OS, although no differences were observed in pCR, LC, or DFS. Innovative multidisciplinary strategies incorporating further time extension of the surgical interval can be safely explored.

Phase II trial of short-course radiotherapy followed by delayed surgery for locoregionally advanced rectal cancer

AIM

A prospective phase II study to investigate the feasibility and the rate of complete pathological response (ypT0) after short-course radiotherapy (SCRT) followed by surgery at 8 weeks.

METHOD

Operable patients with localized rectal cancer staged T3-4N0/+ or T2N+ were eligible and received 25 Gy (in one-third of patients, the gross tumor volume received a simultaneous integrated boost up to a total of 30 Gy) in five consecutive fractions to the posterior pelvis followed by surgery 8 weeks later. Pathological response and surgical toxicity were assessed in all patients.

RESULTS

Fifty-two patients (median age 68 years) completed the study. The median distance of the tumour from the anal verge was 6.5 cm. The median interval to surgery was 52 days. Three-quarters of patients underwent a low anterior resection. All underwent complete surgical resection and 100% had pathological negative margins. Ten per cent had stage ypT0 after radiotherapy. The median length of hospital stay was 8 days. Toxicity was comparable with the rates reported in the literature.

CONCLUSION

In this study, SCRT followed by delayed surgery was feasible and had acceptable toxicity. All patients underwent complete surgical resection and 100% had negative pathological margins. The rate of ypT0 was 10%.

T4 rectal cancer: do we always need an exenteration?

The management of rectal cancer has changed dramatically over the last few decades. Due to improvements in the multimodality treatment and the introduction of neoadjuvant chemoradiation, previously irresectable tumours can nowadays be cured by extensive multivisceral resections. These highly complex operations are associated with significant morbidity and mortality. Due to optimization of chemoradiotherapy, the introduction of IORT, increasing knowledge of tumour pathology and patterns of recurrence the need for extensive surgery diminishes. The question arises which patients with T4 rectal cancer really need extensive surgery and who can safely be considered for an organ preserving approach.

Gene expression profile is associated with chemoradiation resistance in rectal cancer

AIM

Patients with rectal cancer who achieve a complete pathological response after preoperative chemoradiation (CRT) have an improved oncological outcome. Identifying factors associated with a lack of response could help our understanding of the underlying biology of treatment resistance. This study aimed to develop a gene expression signature for CRT-resistant rectal cancer using high-throughput nucleotide microarrays.

METHOD

Pretreatment biopsies of rectal adenocarcinomas were prospectively collected and freshly frozen according to an institutional review board-approved protocol. Total tumour mRNA was extracted and gene expression levels were measured using microarrays. Patients underwent proctectomy after completing standard long-course CRT and the resected specimens were graded for treatment response. Gene expression profiles for nonresponders were compared with those of responders. Differentially expressed genes were analyzed for functional significance using the Ingenuity Pathway Analysis (IPA) software.

RESULTS

Thirty-three patients treated between 2006 and 2009 were included. We derived 812-gene and 183-gene signatures separating nonresponders from responders. The classifiers were able to identify nonresponders with a sensitivity and specificity of 100% using the 812-gene signature, and sensitivity and specificity of 33% and 100% using the 183-gene signature. IPA canonical pathway analysis revealed a significant ratio of differentially expressed genes in the 'DNA double-strand break repair by homologous recombination' pathway.

CONCLUSION

Certain rectal cancer gene profiles are associated with poor response to CRT. Alterations in the DNA double-strand break repair pathway could contribute to treatment resistance and provides an opportunity for further studies.

Retrospective analysis of pathological response in colorectal cancer liver metastases following treatment with bevacizumab

AIMS

Pathological response has been shown to be a predictor for survival after preoperative chemotherapy and surgical resection of colorectal cancer liver metastases. This retrospective analysis evaluated the effect on pathological response of adding bevacizumab to standard neoadjuvant chemotherapy in patients with metastatic colorectal cancer (mCRC) and liver metastases.

METHODS

Patient records from two Spanish centres were retrospectively examined for this analysis. Patients were included if they had stage IV mCRC with liver metastases, were unresectable or marginally resectable tumour before chemotherapy, and had oxaliplatin- or irinotecan-based chemotherapy, with or without bevacizumab, before resection. Tumour response was evaluated using response evaluation criteria in solid tumours (RECIST). Pathological response was assessed by pathologists blinded to treatment.

RESULTS

Ninety-five patients were included. Good pathological responses (PR0/PR1) were observed in 37 patients (39 %). The RECIST response rate was 51 %. Only 42 % of patients with a good pathological response had a complete or partial response according to RECIST, while 57 % of those with a poor pathological response had a complete or partial response according to RECIST. RECIST response rates were similar with and without bevacizumab, although 49 % of bevacizumab-treated patients had a good pathological response versus 27 % of those receiving chemotherapy alone (χ (2) P = 0.0302).

CONCLUSION

Pathological response may be a better indicator of treatment efficacy than RECIST for patients with mCRC receiving bevacizumab in the neoadjuvant setting. Adding bevacizumab to chemotherapy has the potential to increase pathological response rates. Well-designed prospective clinical studies are required to establish the efficacy and tolerability of this approach.

EURECCA consensus conference highlights about rectal cancer clinical management: the radiation oncologist's expert review

BACKGROUND AND PURPOSE

Although rectal and colon cancer management has progressed greatly in the last few decades clinical outcomes still need to be optimized. Furthermore, consensus is required on several issues as some of the main international guidelines provide different recommendations. The European Registration of Cancer Care (EURECCA) drew up documents to standardize management and care in Europe and aid in decision-making.

MATERIAL AND METHODS

In the present section the panel of experts reviews and discusses data from the literature on rectal cancer, focusing on recommendations for selecting between short-course radiotherapy (SCRT) and long-course radio-chemotherapy (LCRTCT) as preoperative treatment as well as on the controversies about adjuvant treatment in patients who had received a pre-operative treatment.

RESULTS

The starting-point of the present EURECCA document is that adding SCRT or LCRTCT to TME improved loco-regional control but did not increase overall survival in any single trial which, in any case, had improved with the introduction of total mesorectal excision (TME) into clinical practice. Moderate consensus was achieved for cT3 anyNM0 disease. In this frame, agreement was reached on either SCRT followed by immediate surgery or LCRTCT with delayed surgery for mesorectal fascia (MRF) negative tumors at presentation. LCRTCT was recommended for tumor shrinkage in MRF+ at presentations but if patients were not candidates for chemotherapy, SCRT with delayed surgery is an option/alternative. LCRTCT was recommended for cT4 anycNM0. SCRT offers the advantages of less acute toxicity and lower costs, and LCRTCT tumor shrinkage and down-staging, with 13-36% pathological complete response (pCR) rates. To improve the efficacy of preoperative treatment both SCRT and LCRTCT have been, or are being, associated with diverse schedules of chemotherapy and even new targeted therapies but without any definitive evidence of benefit. Nowadays, standard treatment is fluoropyrimidine alone since alternative agents and regimens have not been shown to be more active, only more toxic.

CONCLUSIONS

The EURECCA panel summarized available evidence in an attempt to reduce variance in rectal cancer management. This is expected to benefit patients. Results from ongoing randomized trials will help clarify some of the issues that are still under debate.

A Phase II Study of Additional Four-Week Chemotherapy With Capecitabine During the Resting Periods After Six-Week Neoadjuvant Chemoradiotherapy in Patients With Locally Advanced Rectal Cancer

Purpose

The aim of this study is to evaluate the efficacy and the safety of additional 4-week chemotherapy with capecitabine during the resting periods after a 6-week neoadjuvant chemoradiotherapy (NCRT) in patients with locally advanced rectal cancer.

Methods

Radiotherapy was delivered to the whole pelvis at a total dose of 50.4 Gy for 6 weeks. Oral capecitabine was administered at a dose of 825 mg/m² twice daily for 10 weeks. Surgery was performed 2-4 weeks following the completion of chemotherapy.

Results

Between January 2010 and September 2011, 44 patients were enrolled. Forty-three patients underwent surgery, and 41 patients completed the scheduled treatment. Pathologic complete remission (pCR) was noted in 9 patients (20.9%). T down-staging and N down-staging were observed in 32 patients (74.4%) and 33 patients (76.7%), respectively. Grade 3 to 5 toxicity was noted in 5 patients (11.4%). The pCR rate was similar with the pCR rates obtained after conventional NCRT at our institute and at other institutes.

Conclusion

This study showed that additional 4-week chemotherapy with capecitabine during the resting periods after 6-week NCRT was safe, but it was no more effective than conventional NCRT.

Prognostic significance of partial tumor regression after preoperative chemoradiotherapy for rectal cancer: a meta-analysis

BACKGROUND

Complete tumor regression after preoperative chemoradiotherapy for rectal cancer has been associated with better disease-free and overall survival. The survival experience for patients with partial tumor regression is less clear.

OBJECTIVE

The aim of this meta-analysis was to evaluate the prognostic significance of partial response after preoperative chemotherapy on disease-free survival in rectal cancer patients.

DATA SOURCES

Relevant studies were identified by a search of MEDLINE and EMBASE databases with no restrictions to October 31, 2012.

STUDY SELECTION

We included long-course radiotherapy that reported the association between degree of tumor regression and disease-free survival of rectal cancer.

INTERVENTIONS

Direct, indirect, and graph methods were used to extract HRs.

MAIN OUTCOME MEASURES

Study-specific HRs on the disease-free survival were pooled using a random-effects model. Eleven articles in total were selected. Analysis was performed first among the 6 studies that separated partial response from the complete response and later among all 11 of the studies.

RESULTS

Pooled HR was 0.49 (95% CI, 0.28-0.85) for the 6 studies that compared partial response with poor response. It was 0.41 (95% CI, 0.25-0.67) when all 11 of the studies were analyzed together.

LIMITATIONS

The studies were limited by not being prospective, randomized trials, and the tumor regression grades were not uniform.

CONCLUSIONS

Partial tumor response is associated with a 50% improvement in disease-free survival and should be considered as a favorable prognostic factor.

Molecular markers for targeted neoadjuvant rectal cancer therapy

SUMMARY Neoadjuvant chemoradiotherapy is the standard of care for locally advanced rectal cancer. While neoadjuvant chemoradiation has been demonstrated to improve oncological outcomes, there is a wide spectrum of responses to therapy. The ability to predict who will respond favorably or unfavorably to neoadjuvant therapy could prevent unnecessary morbidity and potentially lead to novel therapeutic targets. A number of individual biomarkers and multigene signatures have been investigated as potential means of predicting response to neoadjuvant chemoradiation. While promising, none of these predictive biomarkers have yet been introduced clinically. This review summarizes both individual and multigene biomarkers for rectal cancer response to neoadjuvant chemoradiation.

Optimal time interval between neoadjuvant chemoradiotherapy and surgery for rectal cancer

BACKGROUND

Neoadjuvant chemoradiotherapy (CRT) has been proven to increase local control in rectal cancer, but the optimal interval between CRT and surgery is still unclear. The purpose of this study was to analyse the influence of variations in clinical practice regarding timing of surgery on pathological response at a population level.

METHODS

All evaluable patients who underwent preoperative CRT for rectal cancer between 2009 and 2011 were selected from the Dutch Surgical Colorectal Audit. The interval between radiotherapy and surgery was calculated from the start of radiotherapy. The primary endpoint was pathological complete response (pCR; pathological status after chemoradiotherapy (yp) T0 N0).

RESULTS

A total of 1593 patients were included. The median interval between radiotherapy and surgery was 14 (range 6-85, interquartile range 12-16) weeks. Outcome measures were calculated for intervals of less than 13 weeks (312 patients), 13-14 weeks (511 patients), 15-16 weeks (406 patients) and more than 16 weeks (364 patients). Age, tumour location and R0 resection rate were distributed equally between the four groups; significant differences were found for clinical tumour category (cT4: 17·3, 18·4, 24·5 and 26·6 per cent respectively; P = 0·010) and clinical metastasis category (cM1: 4·4, 4·8, 8·9 and 14·9 per cent respectively; P < 0·001). Resection 15-16 weeks after the start of CRT resulted in the highest pCR rate (18·0 per cent; P = 0·013), with an independent association (hazard ratio 1·63, 95 per cent confidence interval 1·20 to 2·23). Results for secondary endpoints in the group with an interval of 15-16 weeks were: tumour downstaging, 55·2 per cent (P = 0·165); nodal downstaging, 58·6 per cent (P = 0·036); and (near)-complete response, 23·2 per cent (P = 0·124).

CONCLUSION

Delaying surgery until the 15th or 16th week after the start of CRT (10-11 weeks from the end of CRT) seemed to result in the highest chance of a pCR.

Metformin use and improved response to therapy in rectal cancer

Locally advanced rectal cancer is commonly treated with chemoradiation prior to total mesorectal excision (TME). Studies suggest that metformin may be an effective chemopreventive agent in this disease as well as a possible adjunct to current therapy. In this study, we examined the effect of metformin use on pathologic complete response (pCR) rates and outcomes in rectal cancer. The charts of 482 patients with locally advanced rectal adenocarcinoma treated from 1996 to 2009 with chemoradiation and TME were reviewed. Median radiation dose was 50.4 Gy (range 19.8–63). Nearly, all patients were treated with concurrent 5-fluorouracil-based chemotherapy (98%) followed by adjuvant chemotherapy (81.3%). Patients were categorized as nondiabetic (422), diabetic not taking metformin (40), or diabetic taking metformin (20). No significant differences between groups were found in clinical tumor classification, nodal classification, tumor distance from the anal verge or circumferential extent, pretreatment carcinoembryonic antigen level, or pathologic differentiation. pCR rates were 16.6% for nondiabetics, 7.5% for diabetics not using metformin, and 35% for diabetics taking metformin, with metformin users having significantly higher pCR rates than either nondiabetics (P = 0.03) or diabetics not using metformin (P = 0.007). Metformin use was significantly associated with pCR rate on univariate (P = 0.05) and multivariate (P = 0.01) analyses. Furthermore, patients taking metformin had significantly increased disease-free (P = 0.013) and overall survival (P = 0.008) compared with other diabetic patients. Metformin use is associated with significantly higher pCR rates as well as improved survival. These promising data warrant further prospective study.