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Are health-related exclusions keeping too many elderly patients out of cancer trials?

Although most new cases of cancer occur in people aged 65 and over, studies have shown that relatively few people in this age group enroll in clinical trials of new cancer treatments. A new study says requirements that participants in cancer clinical trials be free of other health problems disqualify too many older people from taking part.

Restrictions on trial participation by people who have certain other health problems are known as “protocol exclusions.” These exclusions explain almost all of the underrepresentation of older people in cancer treatment trials, according to the new study, which is published in the April 1, 2003, issue of the Journal of Clinical Oncology (see the journal abstract of the study 2).

The study authors analyzed data on 59,300 patients enrolled in 495 cancer treatment trials sponsored by the National Cancer Institute. They found that only 32 percent of trial participants were aged 65 or over, although 61 percent of all new cancer cases occur in this age group.

Other abnormalities prohibited

Most cancer trials prohibit patients from enrolling if they have any abnormalities of the heart, blood, liver, or kidneys, or if they have had another cancer in the past, the researchers found. Most trials also require that patients be mobile and able to work or live independently.

Trials enrolled fewer older people if they excluded patients with high blood pressure; other heart, lung, or blood abnormalities; or limitations on their ability to perform daily living activities without help. If these exclusions were relaxed, the authors estimated that overall participation in the 495 trials by older people would have jumped to nearly 60 percent.

Medicare policy change not enough

Since June 2000, Medicare has covered patient care costs for beneficiaries who enroll in certain clinical trials, removing a significant barrier to trial participation by older patients. The study authors conclude, however, that this policy change is unlikely, by itself, to substantially increase the number of older people who take part in cancer treatment trials.

Clinical trial investigators must examine protocol exclusions and be certain they are justified before including them in the plan for a trial, say the authors, who were led by Joy H. Lewis, D.O., of the University of California, Los Angeles.

Ideally, protocol exclusions are part of what makes any given clinical trial both scientifically sound and safe for the participants, notes Ted Trimble, M.D., of the National Cancer Institute’s Division of Cancer Treatment Diagnosis and one of the co-authors of the current study. “We structure eligibility criteria for trials in an effort to avoid toxicities that might occur from the treatment itself or from an interaction between the treatment and other health problems,” he said.

Nonetheless, said Trimble, efforts are underway to try to lower the barriers that keep many older participants from cancer clinical trials. “We are working closely with our colleagues at the National Institute on Aging and the Clinical Trials Cooperative Groups to design a new generation of clinical trials for which many additional older patients would be eligible.”

Age-related differences

As the U.S. population ages, the proportion of older cancer patients will continue to increase, Lewis and her colleagues note. Studies of many different cancers have shown age-related differences both in the disease course and in the effect of treatment. For example, older patients with leukemia tolerate intensive treatment less well than younger patients.

To ensure that cancer trials develop and test treatments for all patients with cancer, trials need to enroll sufficient numbers of older people, the authors say. Trials that focus exclusively on older patients or on patients with specific other health problems may be needed, they suggest.

The study did not assess non-health-related factors that may influence older people’s participation in clinical trials. Other studies have suggested that older patients are less likely to seek out trials and prefer obtaining treatment from community physicians rather than from specialty cancer centers. Participation in a clinical trial may require frequent visits to a doctor’s office or hospital, which may be difficult for older people who live alone. Studies elsewhere have also suggested that investigators may be reluctant to enroll older patients in trials.

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