Older patients with colon cancer less likely to receive chemotherapy after surgery

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 the March 17 issue of JAMA, a theme issue on cancer.

Study co-author Robert H. Fletcher, M.D., M.Sc., of Harvard Medical School, Boston, presented the findings of the study at a JAMA media briefing.

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.

Katherine L. Kahn, M.D., of RAND Corporation, Santa Monica, Calif., and colleagues analyzed the use of adjuvant chemotherapy and adverse events by age, through medical records and surveys, in a multiregional group of 675 patients diagnosed with stage III colon cancer from 2003 through 2005, who underwent surgical resection (removal of part of the colon). The patients, who were followed up for as long as 15 months following their diagnosis, were from five regions (Alabama, Iowa, Los Angeles County, northern California, and North Carolina), five integrated health care delivery systems, and 15 Veterans Affairs hospitals.

The researchers found that overall, 513 of 675 patients with stage III colon cancer (75 percent) received any 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. nonusers.

"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 write.

"Systematic monitoring of symptoms and signs among chemotherapy users, combined with interventions to evaluate and treat these clues, could help clinicians support patients in meeting evidence-based treatment dosage and duration goals. Clinicians who identify symptoms and signs early and take steps to avoid serious adverse outcomes may enable their patients to complete recommended treatment courses while also improving quality of life."