Optimal neoadjuvant strategy for signet ring cell carcinoma of the rectum—Is TNT the solution?
Mufaddal Kazi, Divakar Jain, Amita Sekhar Padhy, Munita Menon, Ashwin Desouza, Vivek Sukumar, Jayesh Gori, Vikas Ostwal, Suman Kumar Ankathi, Avanish Saklani
Abstract
INTRODUCTION: The results of total neoadjuvant therapy (TNT) for locally advanced rectal cancers (LARC) cannot be extrapolated to signet-ring cell cancers (SRCC) that have an extremely aggressive biology. METHODS: A retrospective study comparing long course chemoradiation (CTRT) against short course radiation (SCRT) and 12 weeks of chemotherapy for high-risk LARC. Primary endpoints were treatment failure and disease-free survival (DFS) RESULTS: CTRT was given to 74 (59.7%) and SCRT/Chemotherapy to 50 patients (40.3%). Additional chemotherapy was required in 54.1% and 28%, respectively. Except for nodal staging, no other MRI parameter down-staged. Treatment failures were seen in 33.9% and 25.8% had progression. The peritoneum was the commonest site of progression (59.4%). Of the patients that were surgically explored, 63.7% had R0 resections and pathological complete response was seen in 9.7%. At a median follow-up of 35 months, 56.5% had DFS events with a 3-year DFS of 39.5%. Recurrences were noted in 45.1% after curative resections and the 3-year OS/DFS of these patients were 67.2%/56.4%. On multivariate regression, the type of preoperative therapy did not influence treatment failures or DFS. CONCLUSIONS: SRCC is a very aggressive disease and none of the treatment strategies could show superiority over the other with very high peritoneal progression rates and relapses.