Women who are extremely obese are less likely than thinner women to undergo screening for breast and cervical cancer, according to a new study.

Using data from a national health survey, researchers found that severely obese women were about half as likely as normal-weight women to be up-to-date with their mammograms and Pap tests.

The National Cancer Institute recommends that women have a mammogram to detect breast cancer every 1 to 2 years, starting at age 40, and a Pap test to screen for cervical cancer at least once every 3 years, beginning about 3 years after they start having sex.

It’s not clear why severely obese women are less likely to be compliant with these guidelines. But the study found no evidence that their doctors were lax in recommending the screening tests.

Instead, these women appeared less likely to follow their doctors’ advice, according to findings published in the American Journal of Preventive Medicine.

It will be important to figure out why, since obesity has been linked to higher risks of breast and cervical cancers, the study authors point out.

“We are currently conducting focus groups with women and interviews with physicians to determine what can be done to help improve cancer screening among severely obese women,” said lead study author Dr. Jeanne M. Ferrante, of the University of Medicine and Dentistry of New Jersey in Newark.

These discussions have yielded some ideas on what could be done, she told Reuters Health - including making sure doctors’ offices have appropriately sized gowns, scales, exam tables and other equipment, or having special facilities for severely obese women so they don’t feel self-conscious.

Special training for doctors and other health professionals on how to deal with severely obese women sensitively and professionally might also be helpful, according to Ferrante.

The study included 8,289 women between the ages of 40 and 74 years. The researchers found that women who were severely obese were half as likely as normal-weight women to have had a mammogram in the past 2 years and 57-percent less likely to have had a Pap test in the past 3 years.

This was despite the fact that obese women were as likely to have received a doctor’s recommendation to have the screening tests.

It’s uncertain whether women, in particular, find their weight to be a barrier to preventive healthcare. In a previous study, Ferrante and her colleagues found that obese women and men alike had lower rates of colon cancer screening. But, she noted, some other studies have failed to show that obese men undergo less cancer screening.

SOURCE: American Journal of Preventive Medicine, June 2007.