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Older women are still underrepresented in medical trials evaluating treatments for breast cancer, according to a new study.

Of three different types of trials evaluated by researchers, only one had an increase in enrollment of older women with breast cancer between 1985 and 2012. The other two had decreases.

Seeing how older people react to cancer therapies "is crucial to inform decision-making and to optimally serve patients' medical, emotional, and functional needs," the authors of the study write in the Journal of Clinical Oncology, online December 19.

"As physicians and especially in the cancer world, we rely on clinic trials to tell us what to do with our patients," said lead author Dr. Rachel Freedman, of the Dana-Farber Cancer Institute in Boston. "When we don't have good information, we always feel lost about how to take care of these people."

She and her colleagues point out that most cancers occur in older patients. In the U.S., 72,000 cases of breast cancer are diagnosed each year in women age 70 or older, and nearly half of breast cancer deaths occur in that age group.

Despite the heavy cancer burden among the elderly, the researchers say it's been a challenge to recruit them into randomized trials.

The new study included data collected from 1985 to 2012 from participants in breast cancer research under the Alliance for Clinical Trials in Oncology, which is a group of academic and community medical centers that run trials together.

The researchers looked at how the inclusion of older women in adjuvant, neoadjuvant, and metastatic breast cancer trials had changed over that period.

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Overall, 17 percent of all study participants were age 65 or older.

In the trials of adjuvant treatments, the likelihood of enrollment by older women increased by 4 percent a year. But in the trials of neoadjuvant therapies and therapies for metastatic cancers, the likelihood that older women would participate actually decreased over time.

"The bottom line is that we're still doing a poor job," Freedman told Reuters Health. "Our current strategies aren't working."

She said older participants in breast cancer trials tended to be sicker than younger participants. Their cancers had typically spread to more lymph nodes and they were less likely to have tumors that would respond to hormone therapies.

The researchers also found that half of women age 65 and older withdrew from the trials early, compared to about a third of younger participants.

Freedman suggested a number of approaches to help increase the number of older participants in cancer trials. For example, doctors' offices can advise patients about appropriate trials and also provide resources to help them enroll.

On a national level, she said, it's important to design trials for older patients, mandate that older people be included in trials, give medical centers incentives to recruit older people and provide local doctors' offices with necessary support.

"I think if it comes from the top down, it'll filter down and become a priority," she said.