Neoadjuvant short-course radiotherapy followed by consolidation chemotherapy versus long-course chemoradiotherapy in locally advanced rectal cancer: comparison of overall response rates

Abstract Background Management of locally advanced rectal cancer is evolving with current emphasis on the addition of chemotherapy to short course radiotherapy regimen. In this study, we primarily aimed to analyse the difference in overall response rates between the experimental regimen of short-course radiotherapy and sequential chemotherapy and standard long-course CTRT in patients of locally advanced rectal cancer. Methods 33 patients of locally advanced rectal cancer were randomized to a standard long-course CTRT arm and SCRT followed by a sequential chemotherapy arm. Patients in the standard arm received 45Gy in 25 fractions over five weeks with concurrent oral capecitabine while patients in the experimental arm received 25Gy in 5 fractions over 1 week followed by 3 cycles of CAPOX chemotherapy. Clinical and radiological response assessment was conducted after the completion of neoadjuvant treatment, right before surgery. Results Radiological tumour regression showed a statistically non-significant trend favouring the experimental arm (rates of complete tumour regression 35.7% versus 23.1%). Pathological tumour regression rates also showed a trend favouring the experimental arm with a pCR rate of 30% versus 20% in the CTRT arm. a higher number of patients in the short-course arm experimental arm experienced grade 3 diarrhoea, whereas acute skin toxicity was seen only in the CTRT arm. Short-course radiotherapy was tolerated with fewer treatment interruptions compared to CTRT. Conclusions Short-course radiotherapy followed by three cycles of CAPOX chemotherapy is comparable to long-course CTRT in terms of tumour response. This is a better alternative regimen with fewer treatment interruptions in a resource-limited setting.