HSR19-105: The Role of Chemotherapy in Elderly Colorectal Cancer Survivors: An Observational Study

Abstract

Background: Older patients diagnosed with colorectal cancer are not routinely included in clinical trials and are frequently treated with less aggressive chemotherapy. To identify factors associated with treatment initiation in older adults, we conducted an observational study of patients diagnosed with stage I–IV colon or rectal cancer at 65 years and older between 2010 and 2014 across 6 integrated health care systems. Methods: Data were obtained from cancer registries based on chart abstraction and medical records. Time from diagnosis to surgery, chemotherapy, and radiation was measured in weeks and censored when disenrollment, death, or the end of the study period occurred. We assessed patient factors associated with time to chemotherapy initiation using survival analysis methods. Results: Among 8,088 patients diagnosed after the age of 65 with colon cancer, the mean age at diagnosis was 76 years (SD 7.7), 4,150 (51%) were female, and 34% were stage 3 or greater. More than half, 55% (n=4,434) of colon cancers were right-sided (RCC), 23% (n=1833) were left-sided (LCC), and 19% (n=1,559) were rectal cancers. Two-thirds (n=5,201) had moderately differentiated disease. Most (57%) received surgery within 4 weeks and 89% within 6 months of diagnosis (median, 3.4 weeks). At 6 months following diagnosis, 33% of patients had received chemotherapy, and only 4% received radiation. Factors associated with the receipt of chemotherapy were assessed in a multivariable survival model that included age, gender, stage, and site. Patients of older age were less likely to receive chemotherapy (HR, 0.49; 95%CI, 0.45–.53 for 75–79 vs 65–69 years), and more likely for advanced stage, and rectal site. No difference was observed between men and women. Refusal of chemotherapy was reported for only 6% of patients and was associated with age, stage, and site. Six month mortality was 13.3%. Conclusions: Factors associated with the receipt of treatment among older cancer survivors are similar to those in the general population.