Comparison of doublet chemotherapy with monotherapy for vulnerable advanced colorectal cancer patients.

Abstract

143 Background: The efficacy of doublet chemotherapy (fluoropyrimidine + oxaliplatin/irinotecan) for vulnerable colorectal cancer patients is controversial. Some prospective trials have not shown the benefit of doublet chemotherapy for vulnerable patients compared to fluoropyrimidine monotherapy. On the other hand, one trial did show an advantage for doublet chemotherapy in PFS. Moreover, although these trials are designed for vulnerable patients, inclusion was limited by trial criteria, and patient conditions might have been better than those of vulnerable patients in clinical practice. Therefore, the advantage of doublet chemotherapy over monotherapy for vulnerable patients in clinical practice remains unclear. Chemotherapy toxicity and frailty are increased in high modified Glasgow score (mGPS = 2) patients. Therefore, we examined the efficacy of doublet chemotherapy for vulnerable patients, using mGPS. Methods: We retrospectively examined vulnerable advanced colorectal cancer patients who received monotherapy (n = 52) or doublet chemotherapy (n = 195) as 1st line treatment between 2005 and 2016. We defined vulnerable as fulfilling one of the following conditions; age ≥75, ECOG PS = 2, or mGPS = 2. Results: Patient characteristics in the monotherapy group vs the doublet group were as follows; median age (range), 80 (63-88) vs 66 (29-87); gender male/female, 28/24 vs 111/84; ECOG PS 0/1/2, 15/25/12 vs 76/79/40; mGPS = 2, 13 (25%) vs 134 (68%); median metastatic sites (range), 1 (1-3) vs 2 (1-5); presence of ascites, 9 (17%) vs 59 (30%), primary tumor location left, 35 (67%) vs 125 (64%); KRAS mutation 18 (35%) vs 52 (27%); bevacizumab/anti-EGFR antibody, 30/0 vs 79/19. The median PFS was 6.9 months in the monotherapy group and 7.7 months in the doublet group (HR = 1.129, p = 0.480). The median OS was 13.3 months in the monotherapy group and 14.8 months in the doublet group (HR = 0.999, p = 0.994). Multivariate analysis did not show the benefit of doublet chemotherapy in PFS (HR = 0.908, p = 0.615) or OS (HR = 0.764, p = 0.176). Conclusions: This study suggests that doublet chemotherapy may not be beneficial for vulnerable advanced colorectal cancer patients in clinical practice.