Intensity of adjuvant chemotherapy regimens and grade III-V toxicities among elderly stage III colon cancer patients

Purpose: : The aim of this study was to provide insight in the use, intensity and toxicity of therapy with capecitabine and oxaliplatin (CAPOX) and capecitabine monotherapy (CapMono) among elderly stage III colon cancer patients treated in everyday clinical practice. Methods: Data from the Netherlands Cancer Registry were used. All stage III colon cancer patients aged >= 70 years diagnosed in the southeastern part between 2005 and 2012 and treated with CAPOX or CapMono were included. Differences in completion of all planned cycles, cumulative dosages and toxicity between both regimens were evaluated. Results: One hundred ninety-three patients received CAPOX and 164 patients received CapMono; 33% (n = 63) of the patients receiving CAPOX completed all planned cycles of both agents, whereas 55% (n=90) of the patients receiving CapMono completed all planned cycles (P <0.0001). The median cumulative dosage capecitabine was lower for patients treated with CAPOX (163,744 mg/m(2), interquartile range [IQR] 83,397-202,858 mg/m(2)) than for patients treated with CapMono (189,195 mg/m 2, IQR 111,667-228,125 mg/m(2), P = 0.0003); 54% (n = 105) of the patients treated with CAPOX developed grade III-V toxicity, whereas 38% (n = 63) of the patients treated with CapMono developed grade III-V toxicity (P = 0.0026). After adjustment for patient and tumour characteristics, CapMono was associated with a lower odds of developing grade III-V toxicity than CAPOX (odds ratio 0.54, 95% confidence interval 0.33-0.89). For patients treated with CAPOX, the most common toxicities were gastrointestinal (29%), haematological (14%), neurological (11%) and other toxicity (13%). For patients treated with CapMono, dermatological (17%), gastrointestinal (13%) and other toxicity (11%) were the most common. Conclusion: CAPOX is associated with significantly more grade III-V toxicities than CapMono, which had a pronounced impact on the cumulative dosage received and completion of all planned cycles. In this light, CapMono seems preferable over CAPOX