The study analyzed data on 16,396 patients who participated in 164 Southwest Oncology Group (SWOG) treatment trials between 1993 and 1996. The researchers looked at the sex, race, and age of clinical trial participants and compared them to the general population of people with cancer. Although 63 percent of all cancer patients are over age 65, only 25 percent of clinical trial participants are in that age group.

The researchers also found women and blacks were represented in SWOG trials in proportion to the estimated rates in the US cancer patient population. In the late 1980s and early 1990s, federal rules were established requiring that women and minorities be adequately represented in clinical trials.

According to the study authors, there are many reasons for the under-representation of the elderly, such as concern that older patients may not be able to tolerate side effects of the new treatments, or that they may have other diseases that would confuse analysis of the treatment's value.

Because of this, many of the commonly used anticancer treatments have never been thoroughly studied in older patients. If older patients had been better represented in clinical trials, oncologists would now know more about the safety and effectiveness of cancer treatments in that age group and which treatments are not well tolerated, according to the study authors.

"One way to make cancer clinical trials more accessible to older Americans is for federal and private insurance companies to change their policies of reimbursement for participation in clinical trials," said Charles A. Coltman, Jr., MD, a Study Co-author and Chairman of the Southwest Oncology Group. "Many clinical trials are considered 'experimental' and treatment under them is not covered. In addition, transportation to treatment clinics and prescription drugs to control treatment side effects are not covered. If we are to meet the needs of cancer patients in the future, this has to change."

B.J. Kennedy, MD, a pioneer in the field of medical oncology, said this new study reinforces what scientists already knew about older patients. "Older persons with cancer are screened less, staged less and treated less aggressively, inadequately, or not at all," said Dr. Kennedy, who is regents' professor of medicine at the University of Minnesota School of Medicine. "Criteria for clinical trials are too rigid, automatically eliminating the elderly. We need to design clinical trials especially for this group so we won’t have such disparity."