Association between sidedness and survival among chemotherapy refractory metastatic colorectal cancer patients treated with trifluridine/tipiracil or regorafenib.

Background: The impact of sidedness on survival of later-line treatment in patients with metastatic colorectal cancer (mCRC) is undetermined. This study aimed to investigate the association between sidedness and survival among chemotherapy refractory patients with mCRC treated with trifluridine/tipiracil (TAS-102) or regorafenib or both.

Patients and methods: Patients with mCRC treated with TAS-102 or regorafenib between 2015 and 2020 was retrospectively collected. Patients were stratified into TAS-102 first and regorafenib first, then subdivided into TAS-102 followed by regorafenib (T-R) and regorafenib followed by TAS-102 (R-T) groups. The oncologic outcomes were presented with time-to-treatment failure (TTF) and overall survival (OS).

Results: After matching, 376 TAS-102 patients and 376 regorafenib patients were included for outcomes comparison. TTF had insignificant differences while OS was significantly different between TAS-102 and regorafenib groups. Median TTF and OS were 1.9 months versus 2.0 months (P = .701) and 9.1 months versus 7.0 months (P = .008) in TAS-102 and regorafenib, respectively. The OS benefits were consistent regardless primary tumor location. Subgroup analysis with 174 T-R patients and 174 R-T patients was investigated for treatment sequences. TTF and OS had significant differences in both groups. Median TTF and OS were 8.5 months versus 6.3 months (P = .001) and 14.4 months versus 12.6 months (P = .035) in T-R and R-T groups, respectively. The TTF and OS benefits were persisted regardless primary tumor location.

Conclusion: TAS-102 first provided a better survival benefit in chemotherapy refractory patients with mCRC across all sidedness. Further prospective studies are warranted to validate our conclusions.