Impact of age on the chemotherapy treatment and outcomes of advanced colorectal cancer int he community oncology setting

Abstract

Purpose: Current literature regarding the treatment of advanced colorectal cancer (CRC) suggests elderly patients receive the same benefits from treatment as younger patients with a slightly higher of incidence of hematologic toxicity. However, the clinical trials on which this suggestion is based enrolled a small number of elderly patients and were not powered to determine differences based on age group. Clinical trials often maintain strict inclusion and exclusion criteria and may not be representative of the general population treated in community oncology practices. This study evaluated the treatment of advanced CRC in community oncology practices focusing on age-related differences in treatment and outcome. Methods: The primary objective was to compare the proportion of patients receiving combination chemotherapy (irinotecan or oxaliplatin with a fluoropyrimidine) as initial therapy in young (age ≤ 65 years) and elderly (age > 65 years) patients. Secondary objectives included an age based comparison of: 1) the addition of bevacizumab to the initial regimen; 2) overall chemotherapy and monoclonal antibody utilization; 3) death due to advanced CRC; 4) toxicity-related dose changes, delays, chemotherapy and monoclonal antibody therapy changes, hospitalizations and additional clinic visits; and 5) toxicity leading to one of the events listed in the preceding endpoint. Medical records of patients receiving chemotherapy for advanced CRC in community oncology clinics after January 1, 2003 were reviewed. Patient demographics, prior therapy history, chemotherapy regimens, monoclonal antibody therapies, toxicity data, and date of last follow-up or death were collected. Results: Overall, 444 patients (203 ≤ 65 years and 241 > 65 years) with a median follow-up of 303 days, receiving 5,305 cycles of chemotherapy were included. Of the younger patients, 81% received first-line combination chemotherapy compared to 61% of elderly patients (p<0.0001). The utilization of each of the medications: irinotecan, oxaliplatin and bevacizumab was lower in the elderly patients compared to the younger patients (p<0.0001). Progression-related mortality was higher in the elderly cohort compared to the younger patients, 41% and 32% respectively (p=0.02). In the multivariate regression model, age group was no longer predictive of mortality. Better performance status and shorter follow-up were significantly associated with improved survival. Diarrhea was reported significantly more frequently in the elderly population, whereas neutropenia and neurotoxicity occurred more frequently in the younger patients. Conclusions: Elderly patients were less likely to receive first-line combination chemotherapy compared to younger patients and were more likely to experience progression-related mortality.