Utilisation of Adjuvant Chemotherapy and 5-Year Survival Analysis of Prospectively Recorded Cohort Data for Older Adults Versus Younger Adults with Resected Primary Colon Cancer.

Colon cancer is predominantly a disease of older adults. Studies determining the influence of age on outcomes of colon cancer have conflicting results. We aim to determine the long-term outcomes and utilisation of adjuvant chemotherapy of older adults compared with younger adults who had had a resection of a primary colon cancer. Consecutive patients who had resection of a primary colon cancer between January 1, 2000 and December 31, 2010 were identified from a prospective database and stratified into three age groups: ≤ 69 years, 70 to 79 years, and ≥ 80 years. Age-related differences in patients, cancer, and treatment characteristics were determined by chi-square tests. Five-year overall survival and cancer-specific survival were determined by Kaplan-Meier method and by multivariable Cox regression analysis to adjust for potential confounding factors. Of 1135 included patients, 469 (41%) patients were aged ≤ 69 years, 382 (34%) were 70-79 years, and 284 (25%) were ≥ 80 years. Increasing age group predicted more comorbidity (p < 0.001), cardiac comorbidity (p < 0.001), right-sided cancers (p < 0.001), and less adjuvant chemotherapy (stage III only; p < 0.001). Increasing age group was associated with worse overall survival by stage (p < 0.001) but not cancer-specific survival by stage (p = 0.83). Adjuvant chemotherapy in patients with stage III colon cancer independently predicted improved overall survival (p < 0.001) and cancer-specific survival (p = 0.01). Compared with younger adults, older adults with colon cancer had worse survival outcomes and received less adjuvant chemotherapy.