Lower cancer screening rates in obese women show surprising racial twist

A review of 32 studies examining medical imaging of obese patients found that extremely large women are less likely than smaller women to be screened for breast, colon, and cervical cancer. The analysis also revealed surprising trends along racial lines, indicating that overweight white women are less likely than their black counterparts to undergo screening.

"The (obesity) association was not terribly surprising," said lead author Sarah Cohen in an interview. "The racial disparity we saw was more interesting."

Cohen, a graduate student in epidemiology at the University of North Carolina at Chapel Hill, wrote the review for the journal Cancer (published online March 24). Her group analyzed 10 breast, 14 cervical, and eight colorectal cancer studies.

With supervision from Andrew F. Olshan, Ph.D., the researchers conducted a PubMed search between January and February 2007 for each of the three cancer types. They chose relevant articles based on data that either estimated prevalence of screening behaviors or characteristics by body size or estimated the relative risk or relative prevalence of screening by body size.

Cohen concluded that obesity most likely is a barrier to screening for breast and cervical cancers, particularly among white women. The literature regarding obesity and colorectal cancer screening adherence was mixed. Some studies reported an inverse effect of body size on screening behavior, and others reported no effect.

"Among white women, these studies consistently demonstrated that women in the highest BMI categories were less likely to have had a recent mammogram than healthy weight women,'' Cohen's group wrote.

Studies of cervical cancer screening generally supported the hypothesis that being overweight decreased a woman's compliance with cancer screening recommendations. The literature for colorectal cancer screening was more variable, although half of the reviewed studies indicated a possible similar inverse association between body size and screening behavior.

Overall, Cohen's group found few studies that were designed to address the reasons why overweight women - particularly white women - are less likely to receive recommended cancer screening.

One theory regarding the racial disparity is that black women have more positive views of large body shapes than do white women, Cohen said. She also cited other reasons why obese women overall may be less likely to have preventive screening: emotional barriers, provider bias, competing healthcare needs, and inadequate equipment.

Associations may be harder to elucidate for body size and colorectal screening than for mammography or Pap tests because of the multiple modalities used in screening for colorectal cancer, according to the study. Specific modalities may be recommended based in part on body size, but further investigation on individual modalities is needed.

Radiologists concerned about providing service to all patients regardless of body size could take steps as simple as having large-size gowns on hand, she said. Scanners that feature extrawide gantries and high-weight-capacity beds also lower barriers to patient access.

Dr. Elliot K. Fishman, a professor of radiology and oncology at John Hopkins Hospital, is awaiting the arrival of a Siemens scanner with a weight limit of 600 pounds.

"The gantry is wider, and it will have special protocols for obese patients,'' Fishman said.

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