Five Year Survival Outcomes of Prospectively Recorded Cohort Data for Older Adults versus Younger Adults with Resected Primary Rectal Cancer

Background: Rectal cancer predominantly occurs in older adults. We aimed to compare the long-term outcomes of older adults (≥70 years) versus younger adults (<70 years) who had had a primary resection for stage I-IV rectal cancer. Methods: Consecutive patients who had resection of a primary rectal cancer between January 1, 2000 and December 31, 2010 were identified from a prospective database at the Concord Repatriation General Hospital and stratified into two age groups: <70 years and ≥70 years. Age-related differences in patients, cancer, and treatment characteristics were determined by Chi-square tests. 5-year Overall Survival (OS) and Cancer-Specific Survival (CSS) were determined by the Kaplan-Meier method and by multivariable Cox regression analysis. Results: Of 714 included patients, the mean age was 65.8 years (range, 21 - 92 years). 407 (57%) patients were aged < 70 years and 307 (43%) were aged ≥ 70 years. Older age (>70 years) predicted more comorbidity (p < 0.001) and earlier stage (p = 0.01). Of the patients with stage III rectal cancer, older adults (>70 years), compared with younger adults (<70 years), received less neoadjuvant chemotherapy [7/86 (8.1%) vs 25/147 (17.0%), p = 0.058], less neoadjuvant radiotherapy [8/86 (9.3%) vs 42/147 (28.6%), p = 0.001] and less adjuvant chemotherapy [30/86 (34.9%) vs 117/147 (79.6%), p < 0.001]. Older age was associated with worse OS and CSS in stage III (p < 0.001 and p = 0.02 respectively). Adjuvant chemotherapy independently predicted improved OS (p < 0.001) and CSS (p = 0.008) regardless of age. Conclusion: Older adults who had had a resection of stage I-IV primary rectal cancer received less neoadjuvant and adjuvant therapy and had worse OS and CSS than their younger counterparts.