Older Patients Less Likely to Get Adjuvant Chemo for Colorectal Cancer

From Medscape Medical News
Maria Sgambati, MD

March 18, 2010 (Washington, DC) — Older patients who undergo surgery for colon cancer are less likely to receive adjuvant chemotherapy, according to a new study published in the March 17 issue of Journal of the American Medical Association. The findings were reported here at a special press briefing to highlight this issue of the journal, which focuses on cancer.

Investigators analyzed the use of adjuvant chemotherapy in 675 patients diagnosed with stage 3 colon cancer who had already undergone surgical removal of part of the colon as their initial treatment.
Chemotherapy in this setting has demonstrated benefit in reducing disease recurrence and improving survival, regardless of age.
Of these 675 patients, 513 received supplemental chemotherapy, with a large difference based on age; 87% percent of patients younger than 75 years received chemotherapy, compared with 50% of patients older than 75 years.

"Our study shows what others have shown — that older patients in the community are less likely to get chemotherapy, despite evidence-based recommendations," said Robert Fletcher, MD, MSc, an author on the study and professor emeritus of ambulatory care and prevention at Harvard Medical School in Boston, Massachusetts. "It's not clear why they aren't getting it as often as younger patients." Dr. Fletcher speculated that part of the reason might be that physicians are less likely to offer chemotherapy and older patients might be more likely to refuse it, but it's hard to get at that information, he said.

Despite that fact that many patients who get cancer are older, there is a limited but growing body of data on the effectiveness and toxicity of chemotherapy in older patients.

"While we know that older patients can often have the same benefit from chemotherapy as younger patients, most of this information comes from clinical trials where patients are highly selected," said Nancy Keating, MD, associate professor of medicine and healthcare policy at Harvard Medical School and an associate physician at Brigham and Women's Hospital in Boston. "What we don't know is how clinical trial data translate into what's happening in the community. This study is important in that it evaluates what is happening in populations of patients in the community who often have other illnesses."

To conduct this study, Dr. Fletcher and his colleagues examined data gathered as part of the Cancer Care Outcomes Research and Surveillance (CanCORS) project, a consortium supported by the National Institutes of Health and the Department of Veterans Affairs that is looking at outcomes in a cohort of newly diagnosed patients with lung and colorectal cancer.

Older Patients More Likely to Discontinue

Medical record and survey data were used to gather information on chemotherapy regimens, adverse events experienced while on chemotherapy, burden of illness of the patient — that is, other health issues such as diabetes, hypertension, pulmonary disease, and other demographic factors (including income and ethnicity). Patients were drawn from communities across 5 different geographic regions of the United States, from 5 integrated healthcare delivery systems and 15 Veteran's Affairs hospitals.

The study also found that older patients were more likely than younger patients to stop taking chemotherapy, which, in this setting, is often given for at least 6 months, depending on the type of regimen used. After 150 days, 40% of patients older than 65 had discontinued chemotherapy, compared with 25% of patients younger than 65. Stopping treatment early or using lower doses can be problematic. "We don't know whether a shorter duration of treatment or lower doses are as effective," notes Dr. Fletcher.

One possibility for this pattern of discontinuation is that older patients might be more likely to experience toxic effects from chemotherapy. However, data from this study doesn't bear that out. Dr. Fletcher and his colleagues explored this issue in their study and found that 1 in 3 patients receiving chemotherapy experienced an adverse event. Although patients older than 75 had a higher rate of early clinical adverse events — events that might be more related to surgery — after controlling or adjusting for a number of factors, including dose received, older patients were no more likely than younger patients to have late adverse events, they report. This finding might be related to differences that were seen in the type of chemotherapy given or to the health of patients. "Regardless of age, we also found that chemotherapy was given to healthier patients overall, right or wrong," noted Dr. Fletcher. "This may partly explain our findings on adverse events."

Until recently, clinical trials often had upper age limits for patients. Many trials still have very restrictive eligibility criteria, which often exclude patients with comorbidities. However, that is changing, and there does seem to be an emerging opinion that trials are needed to reflect "real-world" scenarios. "I think these trials with older patients only and those that have comorbidities are the way to go," observed Dr. Keating. "While they may be difficult to do, they will provide very important information we need to help patients, particularly as the population ages."