Tailored selection of the interval between neoadjuvant chemoradiotherapy and surgery for locally advanced rectal cancer: analysis based on the pathologic stage or chemoradiation response

Temporal determinants of tumour response to neoadjuvant rectal radiotherapy

Introduction

In locally advanced rectal cancer, longer delay to surgery after neoadjuvant radiotherapy increases the likelihood of histopathological tumour response. Chronomodulated radiotherapy in rectal cancer has recently been reported as a factor increasing tumour response to neoadjuvant treatment in patients having earlier surgery, with patients receiving a larger proportion of afternoon treatments showing improved response. This paper aims to replicate this work by exploring the impact of these two temporal factors, independently and in combination, on histopathological tumour response in rectal cancer patients.

Methods

A retrospective review of all patients with rectal adenocarcinoma who received long course (≥24 fractions) neoadjuvant radiotherapy with or without chemotherapy at a tertiary referral centre was conducted. Delay to surgery and radiotherapy treatment time were correlated to clinicopathologic characteristics with a particular focus on tumour regression grade. A review of the literature and meta-analysis were also conducted to ascertain the impact of time to surgery from preoperative radiotherapy on tumour regression.

Results

From a cohort of 367 patients, 197 patients met the inclusion criteria. Complete pathologic response (AJCC regression grade 0) was seen in 46 (23%) patients with a further 44 patients (22%) having at most small groups of residual cells (AJCC regression grade 1). Median time to surgery was 63 days, and no statistically significant difference was seen in tumour regression between patients having early or late surgery. There was a non-significant trend towards a larger proportion of morning treatments in patients with grade 0 or 1 regression (p = 0.077). There was no difference in tumour regression when composite groups of the two temporal variables were analysed. Visualisation of data from 39 reviewed papers (describing 27379 patients) demonstrated a plateau of response to neoadjuvant radiotherapy after approximately 60 days, and a meta-analysis found improved complete pathologic response in patients having later surgery.

Conclusions

There was no observed benefit of chronomodulated radiotherapy in our cohort of rectal cancer patients. Review of the literature and meta-analysis confirms the benefit of delayed surgery, with a plateau in complete response rates at approximately 60-days between completion of radiotherapy and surgery. In our cohort, time to surgery for the majority of our patients lay along this plateau and this may be a more dominant factor in determining response to neoadjuvant therapy, obscuring any effects of chronomodulation on tumour response. We would recommend surgery be performed between 8 and 11 weeks after completion of neoadjuvant radiotherapy in patients with locally advanced rectal cancer.

Dose-time fractionation schedules of preoperative radiotherapy and timing to surgery for rectal cancer

Chemoradiotherapy (CRT) is extensively used prior to surgery for rectal cancer to provide significantly better local control, but the radiotherapy (RT), as the other component of CRT, has been subject to less interest than the drug component in recent years. With considerable developments in RT, the use of advanced techniques, such as intensity-modulated radiotherapy (IMRT) in rectal cancer, is garnering more attention nowadays. The radiation dose can be better conformed to the target volumes with possibilities for synchronous integrated boost without increased complications in normal tissue. Hopefully, both local recurrence and toxicities can be further reduced. Although those seem to be of interest, many issues remain unresolved. There is no international consensus regarding the radiation schedule for preoperative RT for rectal cancer. Moreover, an enormous disparity exists regarding the RT delivery. With the advent of IMRT, variations will likely increase. Moreover, time to surgery is also quite variable, as it depends upon the indication for RT/CRT in the clinical practices. In this review, we discuss the options and problems related to both the dose-time fractionation schedule and time to surgery; furthermore, it addresses the research questions that need answering in the future.

Meta-analysis of the effect of extending the interval after long-course chemoradiotherapy before surgery in locally advanced rectal cancer

BACKGROUND

The current standard of care in locally advanced rectal cancer (LARC) is neoadjuvant long-course chemoradiotherapy (nCRT) followed by total mesorectal excision (TME). Surgery is conventionally performed approximately 6-8 weeks after nCRT. This study aimed to determine the effect on outcomes of extending this interval.

METHODS

A systematic search was performed for studies reporting oncological results that compared the classical interval (less than 8 weeks) from the end of nCRT to TME with a minimum 8-week interval in patients with LARC. The primary endpoint was the rate of pathological complete response (pCR). Secondary endpoints were recurrence-free survival, local recurrence and distant metastasis rates, R0 resection rates, completeness of TME, margin positivity, sphincter preservation, stoma formation, anastomotic leak and other complications. A meta-analysis was performed using the Mantel-Haenszel method.

RESULTS

Twenty-six publications, including four RCTs, with 25 445 patients were identified. A minimum 8-week interval was associated with increased odds of pCR (odds ratio (OR) 1·41, 95 per cent c.i. 1·30 to 1·52; P < 0·001) and tumour downstaging (OR 1·18, 1·05 to 1·32; P = 0·004). R0 resection rates, TME completeness, lymph node yield, sphincter preservation, stoma formation and complication rates were similar between the two groups. The increased rate of pCR translated to reduced distant metastasis (OR 0·71, 0·54 to 0·93; P = 0·01) and overall recurrence (OR 0·76, 0·58 to 0·98; P = 0·04), but not local recurrence (OR 0·83, 0·49 to 1·42; P = 0·50).

CONCLUSION

A minimum 8-week interval from the end of nCRT to TME increases pCR and downstaging rates, and improves recurrence-free survival without compromising surgical morbidity.

Tumor location as an indication for adjuvant radiotherapy in pT3N0 rectal cancer after surgery

Background

The optimal care for pT3N0 rectal cancer remains controversial. And whether tumor location can be used to guide the administration of adjuvant radiotherapy for pT3N0 rectal cancer is not fully confirmed. The current study was designed to identify the benefit of adjuvant radiotherapy for pT3N0 rectal cancer.

Methods

We performed a retrospective study of 265 pT3N0 rectal cancer patients who were treated by surgery and adjuvant therapy from Mar. 2005 to Sept. 2015. All patients were divided into two groups according to receiving adjuvant radiotherapy or not. Overall survival (OS), disease-free survival (DFS) were compare between patients who did and did not receive adjuvant radiotherapy. Multivariate analysis was performed to explore clinical factors significantly associated with DFS, local recurrence-free survival (LRFS) and distant metastasis-free survival (DMFS).

Results

For patients with lower tumor, DFS in adjuvant chemo-radiotherapy group was higher than that in adjuvant chemotherapy group. Besides, the rates of local recurrence and distant metastasis were found lower in patients who did receive adjuvant radiotherapy than those who did not. For patients with upper tumor, the 5-year OS and DFS were similar between groups of adjuvant chemotherapy and adjuvant chemo-radiotherapy. Multivariable analysis indicated both the CEA and tumor location were independent predictors of LRFS. And adjuvant radiotherapy predicted the DFS, LRFS and DMFS in lower rectal cancer patients.

Conclusion

Tumor location can serve as an indication for the administration of adjuvant radiotherapy in pT3N0 rectal cancer patients.

Predictive role of microRNA-related genetic polymorphisms in the pathological complete response to neoadjuvant chemoradiotherapy in locally advanced rectal cancer patients

In rectal cancer, a pathologic complete response (pCR) to pre-operative treatment is a favourable prognostic marker, but is reported in a minority of the patients. We aimed at identifying microRNA-related host genetic polymorphisms predictive of pCR.

A panel of 114 microRNA-related tagging polymorphisms was selected and analyzed on 265 locally advanced rectal cancer patients treated with neoadjuvant chemo-radiotherapy. Patients were stratified in two subgroups according to the radiotherapy dose (50.4Gy for 202 patients, 55.0Gy for 78 patients). Interactions among genetic and clinical-pathological variants were investigated by recursive partitioning analysis.

Only polymorphisms with a consistent significant effect in the two subgroups of patients were selected as predictive markers of pCR. The results were validated by bootstrap analysis. SMAD3-rs744910, SMAD3-rs745103, and TRBP-rs6088619 were associated to an increased chance of pCR (p=0.0153, p=0.0471, p=0.0125). DROSHA-rs10719 and SMAD3-rs17228212 had an opposite detrimental effect on pathological tumour response (p=0.0274, p=0.0049). Recursive partitioning analysis highlighted that a longer interval time between the end of radiotherapy and surgery increases the chance of pCR in patients with a specific combination of SMAD3-rs744910 and TRBP-rs6088619 genotypes.

This study demonstrated that microRNA-related host genetic polymorphisms can predict pCR to neo-adjuvant chemo-radiotherapy, and could be used to personalize the interval time between the end of radiotherapy and surgery.

Optimal Interval to Surgery After Neoadjuvant Chemoradiotherapy in Rectal Cancer: A Systematic Review and Meta-analysis

This study aimed to evaluate the influence of a waiting interval of ≥ 8 weeks between the end of preoperative neoadjuvant chemoradiotherapy (nCRT) and surgery on the outcomes of patients with locally advanced rectal cancer. We conducted a comprehensive literature review of retrospective and prospective studies from PubMed, Embase, and Cochrane Library databases to investigate the length of the preoperative nCRT-surgery waiting interval and outcomes in patients with locally advanced rectal cancer. The primary outcome measure was pathologic complete response (pCR) rate. Secondary outcome measures included overall survival, disease-free survival, operative time, and the incidence of local recurrence, postoperative complications, anastomotic leakage, and sphincter-preserving surgery. Standardized mean differences and risk ratios were calculated. Thirteen studies involving 19,652 patients were included. The meta-analysis demonstrated that pCR was significantly increased in patients with locally advanced rectal cancer and a waiting interval of ≥ 8 weeks between preoperative nCRT and surgery compared to a waiting interval of < 8 weeks, or a waiting interval of > 8 weeks compared to ≤ 8 weeks (risk ratio = 1.25; 95% confidence interval, 1.16-1.35; P < .0001). There were no significant differences in overall survival, disease-free survival, operative time, or incidence of local recurrence, postoperative complications, or sphincter-preserving surgery. This study revealed that performing surgery after a waiting interval of ≥ 8 weeks after the end of preoperative nCRT is safe and efficacious for patients with locally advanced rectal cancer, significantly improving pCR without increasing operative time or incidence of postoperative complications, compared to a waiting interval of ≤ 8 weeks.

Pharmacogenetics Biomarkers and Their Specific Role in Neoadjuvant Chemoradiotherapy Treatments: An Exploratory Study on Rectal Cancer Patients

Background: Pathological complete response (pCR) to neoadjuvant chemoradiotherapy (CRT) in locally advanced rectal cancer (LARC) is still ascribed to a minority of patients. A pathway based-approach could highlight the predictive role of germline single nucleotide polymorphisms (SNPs). The primary aim of this study was to define new predictive biomarkers considering treatment specificities. Secondary aim was to determine new potential predictive biomarkers independent from radiotherapy (RT) dosage and cotreatment with oxaliplatin. Methods: Thirty germ-line SNPs in twenty-one genes were selected according to a pathway-based approach. Genetic analyses were performed on 280 LARC patients who underwent fluoropyrimidine-based CRT. The potential predictive role of these SNPs in determining pathological tumor response was tested in Group 1 (94 patients undergoing also oxaliplatin), Group 2 (73 patients treated with high RT dosage), Group 3 (113 patients treated with standard RT dosage), and in the pooled population (280 patients). Results: Nine new predictive biomarkers were identified in the three groups. The most promising one was rs3136228-MSH6 (p = 0.004) arising from Group 3. In the pooled population, rs1801133-MTHFR showed only a trend (p = 0.073). Conclusion: This exploratory study highlighted new potential predictive biomarkers of neoadjuvant CRT and underlined the importance to strictly define treatment peculiarities in pharmacogenetic analyses.

Genetic polymorphisms in 5-Fluorouracil-related enzymes predict pathologic response after neoadjuvant chemoradiation for rectal cancer

BACKGROUND

Many patients with rectal cancer undergo preoperative neoadjuvant chemoradiation, with approximately 70% exhibiting pathologic downstaging in response to treatment. Currently, there is no accurate test to predict patients who are likely to be complete responders to therapy. 5-Fluorouracil is used regularly in the neoadjuvant treatment of rectal cancer. Genetic polymorphisms affect the activity of thymidylate synthase, an enzyme involved in 5-Fluorouracil metabolism, which may account for observed differences in response to neoadjuvant treatment between patients. Detection of genetic polymorphisms might identify patients who are likely to have a complete response to neoadjuvant therapy and perhaps allow them to avoid operation.

METHODS

DNA was isolated from whole blood taken from patients with newly diagnosed rectal cancer who received neoadjuvant therapy (n = 50). Response to therapy was calculated with a tumor regression score based on histology from the time of operation. Polymerase chain reaction was performed targeting the promoter region of thymidylate synthase. Polymerase chain reaction products were separated using electrophoresis to determine whether patients were homozygous for a double-tandem repeat (2R), a triple-tandem repeat (3R), or were heterozygous (2R/3R). A single nucleotide polymorphism, 3G or 3C, also may be present in the second repeat unit of the triple-tandem repeat allele. Restriction fragment length polymorphism assays were performed in patients with at least one 3R allele using HaeIII.

RESULTS

Patients with at least 1 thymidylate synthase 3G allele were more likely to have a complete or partial pathologic response to 5-Fluorouracil neoadjuvant therapy (odds ratio 10.4; 95% confidence interval, 1.3-81.6; P = .01) than those without at least one 3G allele.

CONCLUSION

Identification of rectal cancer patients with specific genetic polymorphisms in enzymes involved in 5-Fluorouracil metabolism seems to predict the likelihood of complete or partial pathologic response to preoperative neoadjuvant therapy.

Effect of Interval between Neoadjuvant Chemoradiotherapy and Surgery on Oncological Outcome for Rectal Cancer: A Systematic Review and Meta-Analysis

Aim. To evaluate the influence of interval between neoadjuvant chemoradiotherapy (NCRT) and surgery on oncological outcome. Methods. A systematic search was conducted in PubMed, the Cochrane Library, and Embase databases for publications reporting oncological outcomes of patients following rectal cancer surgery performed at different NCRT-surgery intervals. Relative risk (RR) of pathological complete response (pCR) among different intervals was pooled. Results. Fifteen retrospective cohort studies representing 4431 patients met the inclusion criteria. There was a significantly increased rate of pCR in patients treated with surgery followed 7 or 8 weeks later (RR, 1.45; 95% CI, 1.18-1.78; and P < 0.01 and RR, 1.49; 95% CI, 1.15-1.92; and P = 0.002, resp.). There is no consistent evidence of improved local control or overall survival with longer or shorter intervals. Conclusion. Performing surgery 7-8 weeks after the end of NCRT results in the highest chance of achieving pCR. For candidates of abdominoperineal resection before NCRT, these data support implementation of prolonging the interval after NCRT to optimize the chances of pCR and perhaps add to the possibility of ultimate organ preservation.