Short-Course Radiation Therapy Versus Long-Course Chemoradiation in the Neoadjuvant Treatment of Locally Advanced Rectal Cancer: New Insights from Randomized Trials

Neoadjuvant short-course radiotherapy with consolidation chemotherapy for locally advanced rectal cancer: a systematic review and meta-analysis

BACKGROUND

Short-course radiotherapy with consolidation chemotherapy (SCRT-CCT) has emerged as a promising alternative to the long course chemoradiotherapy (LCRT) regimen in locally advanced rectal cancer management. The systematic review and meta-analysis is aimed at summarizing current evidence on SCRT-CCT and comparing it to LCRT.

MATERIAL AND METHODS

Electronic databases of MEDLINE, Web of Science, and Cochrane library were searched using a predefined search strategy returning 3314 articles. This review included 11 studies (6 randomized trials and 5 non-randomized studies) on SCRT-CCT regimen based on seven different cohorts. Weighted arithmetic means and forest plots were generated to determine summary estimates.

RESULTS

The probability of achieving pathological complete response (pCR) was higher with SCRT-CCT compared to LCRT (risk ratio [RR] = 1.75, 95% confidence interval [CI]: 1.41-2.19). No statistically significant difference in 3-year overall survival (OS) was observed between the two groups (RR= 1.06, 95% CI: 0.98-1.14). The weighted arithmetic mean of 3-year OS and pCR was 83.6% versus 80.9%, and 24.5% versus 13.6% for SCRT-CCT and LCRT, respectively. R0 resection and T-downstaging rates ranged from 69.2-100% to 47-75% for SCRT-CCT, and 71-92.3% and 41-75% for LCRT, respectively. The regimens had similar compliance, postoperative, and late toxicity, however, acute toxicity rates varied primarily due to differences in treatment protocols.

CONCLUSIONS

This review highlights the ability of SCRT-CCT to produce improved tumor response with comparable OS, R0 resection, and T-downstaging at the cost of increased acute toxicity. However, heterogeneity in treatment protocols across studies makes it difficult to provide definitive conclusions regarding the regimen. Several ongoing trials are expected to provide further evidence confirming the findings of RAPIDO trial and detail appropriate SCRT-CCT protocols to improve oncological outcomes, minimize toxicity, and determine its effectiveness as the standard-of-care for locally advanced rectal cancer patients.

Complete pathological response in rectal cancer utilising novel treatment strategies for neo-adjuvant therapy: A systematic review

BACKGROUND

Locally advanced rectal cancer is routinely treated with neo-adjuvant long course chemoradiotherapy or short course radiotherapy, followed by total mesorectal excision. Not all patients respond to this treatment and there has been an emergence of novel treatment strategies designed to improve outcomes for these patients. This systematic review aims to assess the current novel neo-adjuvant treatment strategies being utilised in the treatment of patients with rectal cancer and how these impact pathological complete response (pCR) rates.

METHODS

A systematic review of the literature was performed to evaluate pathological response in patients with rectal cancer receiving novel neo-adjuvant therapy. EMBASE and Medline electronic databases were searched for relevant articles. Articles published between January 2008 and February 2019 were retrieved. Included studies underwent critical appraisal and complete pathological response rates were recorded.

RESULTS

Of the initial 1074 articles identified, 217 articles fulfilled the inclusion criteria, of these 60 articles (4359 patients) were included. Neo-adjuvant therapy delivered included novel long course chemoradiation therapy, neoadjuvant chemotherapy alone, addition of a biological agent, total neo-adjuvant therapy, novel short course radiation therapy and studies utilising biomarkers to select patients for therapy. Complete pathological response rates ranged from 0 to 60%.

CONCLUSION

A validated novel neo-adjuvant therapy that significantly increases pCR rates in patients with rectal cancer has not been identified.

Recent advances in (chemo-)radiation therapy for rectal cancer: a comprehensive review

The role of radiation therapy in the treatment of (colo)-rectal cancer has changed dramatically over the past decades. Introduced with the aim of reducing the high rates of local recurrences after conventional surgery, major developments in imaging, surgical technique, systemic therapy and radiation delivery have now created a much more complex environment leading to a more personalized approach. Functional aspects including reduction of acute or late treatment-related side effects, sphincter or even organ-preservation and the unsolved problem of still high distant failure rates have become more important while local recurrence rates can be kept low in the vast majority of patients. This review summarizes the actual role of radiation therapy in different subgroups of patients with rectal cancer, including the current standard approach in different subgroups as well as recent developments focusing on neoadjuvant treatment intensification and/or non-operative treatment approaches aiming at organ-preservation.