Even though older patients with colon cancer are less likely to receive chemotherapy following surgery because of concerns of adverse events, new research indicates that when they do receive this treatment, it is less toxic and of shorter duration than therapy younger patients receive, and older patients experience fewer adverse events, according to a study in JAMA.
Study co-author Robert H. Fletcher, M.D., M.Sc., of Harvard Medical School, Boston, presented the findings. Randomized trials have shown reductions in cancer death and recurrence in patients with stage III colon cancer treated with adjuvant (supplemental [after surgery]) chemotherapy, with clinical trials also showing that surgery and adjuvant chemotherapy increases survival over surgery alone in selected patients with this stage of colon cancer. But in practice, older patients with stage III colon cancer are much less likely to receive this treatment.
“Physicians cite the lack of randomized controlled trials evaluating the effectiveness of adjuvant chemotherapy for patients older than 80 years as well as comorbid [co-existing illnesses] conditions and drug toxicities as the most common reasons for not treating older patients with adjuvant chemotherapy,” the authors write.
Researchers found that overall, 513 of 675 patients with stage III colon cancer (75 percent) received adjuvant chemotherapy. Of the 202 patients 75 years and older, 101 (50 percent) received supplemental chemotherapy compared with 87 percent of younger patients. Patients aged 65 years and older were more likely than younger patients to discontinue chemotherapy at all follow-up times. For example, by 150 days, 40 percent of patients at least 65 years old had discontinued chemotherapy, compared to 25 percent of younger patients. Among patients receiving adjuvant chemotherapy, adjusted rates of late clinical adverse events were lower for patients 75 years and older vs. for younger patients.
Regarding adverse events, 24 percent of patients had at least 1 adverse event (defined as 31 days after resection and 15 months after diagnosis). These events occurred in more than twice as many patients receiving vs. not receiving adjuvant chemotherapy. The average number of unique adverse events was also higher for adjuvant chemotherapy users vs. non-users.
“Strategies to help clinicians uncertain about the safety of adjuvant chemotherapy for older patients with comorbidity could increase the likelihood that evidence-based chemotherapy benefits are realized in population-based settings. Using decision support tools built on published trials and population-based analyses such as these can help clinicians predict effectiveness of chemotherapy, even for patients with comorbid conditions and advanced age,” the authors wrote.