Benefits from Adjuvant Treatment for Colon Cancer in Older vs. Younger Patients

Previously reported results from the IDEA clinical trial support 3 months of adjuvant fluorinated pyrimidine plus oxaliplatin as the standard treatment for most patients with stage III colon cancer (NEJM JW Oncol Hematol Apr 3 2018 and N Engl J Med; 378:1177). However, debate continues whether oxaliplatin should be added to adjuvant chemotherapy in older patients. Now, in a combined analysis of 12 randomized trials in the IDEA and ACCENT databases, investigators compared outcomes between patients aged ≥70 and <70 years.

Of nearly 18,000 patients, 24% were ≥70 years; compared with younger patients, they were more frequently male and had ECOG PS >1, T4 tumors located in the proximal colon, microsatellite- instability–high status, and BRAF^V600E mutations. More patients <70 than >70 received 6 months of fluorouracil, leucovorin, and oxaliplatin (FOLFOX; 51.9% vs. 39.4%), whereas more patients >70 received capecitabine and oxaliplatin (CAPOX) either for 3 months (17.5% vs. 13.2%) or 6 months (22.0% vs.18.5%).

At a median follow-up of 75.8 months, multivariable analysis showed no significant difference in time to recurrence between age groups overall or between age groups among those treated with 6-month or 3-month regimens. However, disease-free survival (DFS) and overall survival (OS) were shorter in the older group overall and among the 6-month and 3-month groups. Among older patients, time to recurrence was shorter with 3 versus 6 months of treatment (hazard ratio, 1.19; P=0.012), but therapy duration had no effect on DFS or OS.

Rates of early treatment discontinuation were higher in patients >70 than in those <70 (22.0% vs. 15.5%; P<0.001), especially among patients who received 6-month regimens (28.9% vs. 19.0%; P< 0.001). Among patients treated with CAPOX, those >70 had higher rates of diarrhea, neutropenia, and mucositis.