A review of cancer screening studies shows that white women who are obese are less likely than healthy weight women to get the recommended screenings for breast and cervical cancer, according to researchers at the University of North Carolina at Chapel Hill's School of Public Health.
The trend was not seen as consistently among black women; however there were fewer high quality studies that examined black women separately.
"Obesity is increasing, and so is the evidence that obesity increases the risk of certain cancers like colorectal cancer and post-menopausal breast cancer," said Sarah S. Cohen, lead author of the article published online March 24 by the American Cancer Society. "It's a disturbing trend, then, to see that women who are at increased risk of cancer because of their body size are less likely to be receiving screening tests that can detect cancer early, when it is treatable."
Cohen and her colleagues from the UNC School of Public Health's epidemiology department and the UNC Lineberger Comprehensive Cancer Center reviewed 32 relevant published studies on breast, cervical and colorectal cancers that considered associations between obesity and screening tests recommended for women in the United States.
The most consistent associations reported across all the studies were for cervical cancer screenings, with fewer women getting the recommended screening test (Papanicolaou -- or Pap -- tests) as body mass index increased. The studies showed a stronger trend among white women than black women.
The studies also showed lower rates of mammograms -- which screen for breast cancer -- among obese white women compared to healthy weight women. Again, this trend was not observed in black women. Body size was not consistently related to screening for colorectal cancer among any groups of women in the studies that were reviewed.
Breast, cervical and colorectal cancers accounted for 326,290 new cancers cases and 69,850 cancers deaths in 2007 among women in the U.S., according to the American Cancer Society. The percentage of American women who are overweight or obese has been increasing steadily in recent decades. Between 1976 and 2004, the percentage of overweight women rose from 39 percent to 57 percent in white women, and from 63 percent to 80 percent among black women. According to a study published in the New England Journal of Medicine in 2003, 20 percent of cancer deaths in the U.S. in 2000 were attributable to obesity.
"Our review doesn't tell us why larger women are not getting screened as frequently for these cancers," Cohen said. "It only reveals the trend. We think this pattern should be studied more thoroughly. And in the meantime, some additional effort should be made to reach women at increased risk of cancer because of their body size and encourage them to get screenings that could save their lives."
In addition to Cohen, the review was written by Andrew Olshan, Ph.D., chair of the UNC epidemiology department, adjunct research professor in the UNC School of Medicine's department of otolaryngology/head and neck surgery, and program leader for cancer epidemiology in the UNC Lineberger Comprehensive Cancer Center; Rachel T. Palmieri, Sarah J. Nyante, Daniel O. Koralek, Sangmi Kim, Ph.D.and Patrick Bradshaw. The review was developed as the course project in Dr. Olshan's advanced cancer epidemiology class.
The review was supported in part by grants from the National Cancer Institute.
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