MONDAY, June 8, 2009 (HealthDay News) -- Women are underrepresented in clinical cancer research published in the world's most influential medical journals, a new study says.
The findings raise concerns that scientists aren't learning all they can about gender differences in response to chemotherapy and other cancer treatments.
Researchers analyzed 661 prospective studies about types of cancer that afflict both genders at relatively equal rates, including colon cancer, oral cancers, lung cancer, brain tumors and lymphomas. The studies included more than one million participants in all.
Women made up 37 percent of participants in studies not receiving government funding. Studies receiving government funding had a slightly better record of including women, with women representing 41 percent of participants, the analysis showed.
"In the vast majority of individual studies we analyzed, fewer women were enrolled than we would expect given the proportion of women diagnosed with the type of cancer being studied," study author Dr. Reshma Jagsi, assistant professor of radiation oncology at the University of Michigan Medical School, said in a university news release.
"It's so important that women are appropriately represented in research. We know there are biological differences between the sexes, as well as social and cultural differences. Studies need to be able to assess whether there are differences in responses to treatment," she added.
In the report, published in the July 15 issue of the journal Cancer, the researchers looked at all original clinical cancer research published in 2006 in five major cancer journals (the Journal of Clinical Oncology, the Journal of the National Cancer Institute, The Lancet Oncology, Clinical Cancer Research and Cancer) and three major general medical journals (the New England Journal of Medicine, the Journal of the American Medical Association and The Lancet).
The importance of including women in clinical research is stressed in the U.S. National Institutes of Health's Revitalization Act of 1993, which states that enrolling adequate numbers of women in clinical trials allows for subgroup analysis.
Researchers have often been told to avoid including vulnerable populations in their studies, including women of childbearing age. "By protecting them from research, we're excluding them," Jagsi said.
Other barriers to clinical trial participation among women include lack of information and the perception that the studies will interfere with personal responsibilities, such as child care, previous research has found.
And it is true that participating in research studies can be time intensive, Jagsi said. For women juggling the demands of child care, a cancer diagnosis and even a job, Jagsi suggests providing compensation to help with transportation or child care expenses could be helpful.
"Women today are often stretched very thin trying to deal with the balance between domestic responsibilities, their cancer diagnosis, and often a career as well," Jagsi said. "They may be particularly likely to find clinical trials too burdensome."
According to senior author Dr. Peter Ubel, director of the Center for Behavioral and Decision Sciences in Medicine at the University of Michigan, women are not intentionally underrepresented.
"Clinical researchers are not purposely trying to exclude women from their studies. All the more reason they need to consciously and earnestly revise their recruitment methods to give more women a chance to volunteer," Ubel said in the news release.
The U.S. National Cancer Institute has more on signing up for clinical trials.