395P Randomized control trial to assess radiological and pathological response after neo adjuvant concomitant chemo radiotherapy vs. sequential short course radiotherapy (SCRT) followed by chemotherapy in locally advanced rectal cancer (LARC)

Abstract

Background: Incidence of rectal cancer and disease at younger age is increasing. Unlike colon cancer, only age and gender are the strong associated risk factors of rectal cancer. Surgical resection remains main stay of treatment for rectal carcinoma which appears to be inadequate in case of LARC (stage II/III) necessitating multimodality approach using chemotherapy and radiotherapy with various sequences, allowing better tumor control.Methods: A total of 108 patients with LARC were randomly divided in 2 equal arms. Arm A received SCRT (25 Gy in 5 fractions) followed by 2 months of chemotherapy with folfox4 while arm B was treated with conventional long-course RT (45-50 Gy in 25-30 fractions) and concomitant 5-FU infusion. Radiological response to the treatment was assessed at 11-12 weeks of its start using RECIST criteria. Treatment related toxicities were noted using CTCAE V 4.0. All the cases were discussed in MDT meeting and selected ones underwent surgery. Pathological response was determined on histopathogy specimen. Data was entered and analyzed using SPSS v.23. Initial frequencies, mean and percentages of data were obtained. Independent sample t test with confidence interval of 95% was used for comparison between two arms with <0.05 taken as significant.Results: According to RECIST criteria, Objective Response Rate (ORR) was seen in 41(75.9%) patients in arm A and 33(61.1%) patients in arm B (p¼0.131). Stable disease (SD) was seen in 7(13%) patients in both the arms while 6(11.1%) in arm A and 14(25.9%) in arm B showed disease progression on Radiological investigations. After MDT discussion, 41(75.9%) patients in arm A and 33(61.1%) in arm B underwent surgical resection. Pathological Complete Response (pCR) was achieved in 7(17.1%) patients in arm A and 4(12.1%) in arm B (p¼0.745). Comparing both arms, febrile neutropenia (p¼0.023) and grade III/IV proctitis (p¼0.000) were found to be significantly common in arm A. Conclusions:No statistically significant difference in ORR and pCR was seen between two arms. However, febrile neutropenia and proctitis was found to be significantly more common in short course RT arm.Legal entity responsible for the study: The authors.