Prognostic Significance of Interaction Between Somatic APC Mutations and 5-Fluorouracil Adjuvant Chemotherapy in Taiwanese Colorectal Cancer Subjects

Objective: The correlations between adenomatous polyposis coli (APC) mutations and 5-fluorouracil (5-FU) adjuvant chemotherapy and colorectal cancer (CRC) patients' prognosis are not well known. We performed an exploratory Study to investigate the association between APC mutations and the survival of Taiwanese CRC subjects who received 5-FU adjuvant chemotherapy. Methods: Full-length APC gene isolated from tumor tissue and adjacent normal colon tissue from 117 CRC subjects was sequenced. Various characteristics of the 117 subjects were recorded and used in the Cox proportionalhazard model analyses. Results: Although the subject survival rate was associated with the cancer stage, but not with the occurrence of APC mutations. we demonstrate a significant interaction between the somatic APC mutations and 5-FU adjuvant chemotherapy to the prognosis of CRC subjects. Subjects carrying APC mutation(s) and receiving 5-FU adjuvant chemotherapy demonstrate increased hazards (vs. no APC mutation or chemotherapy) for all cause (hazard ratios = 5.565; P = 0.042) or CRC deaths (hazard ratios = 6.920; P = 0.043). 5-FU adjuvant chemotherapy only decreases hazards in CRC subjects without APC mutation(s) for all cause death (hazard ratios = 0.257; P 0.003) or CRC death (hazard ratios = 0.342; P = 0.028). Conclusions: 5-FU adjuvant chemotherapy only prevents CRC subjects without somatic APC mutation(s) from all cause death or CRC death. It needs further studies with larger sample size and longer follow-up time to confirm these results.