No one knows why extra pounds heighten the likelihood that women will avoid mammograms or Pap smears. And it's not known why obesity seems to have no significant effect on colorectal screening, the researchers said.
However, the findings do point to a problem that deserves attention in the doctor's office, said study lead author Sarah S. Cohen, a graduate student in the department of epidemiology at the University of North Carolina at Chapel Hill.
"Because obesity is becoming an increasing problem in our health-care system, encouraging women who are overweight and obese to be screened may be especially important," she said. "It's important for physicians to address it and encourage women to be screened."
According to Cohen, the screening rates for breast and cervical cancer are fairly high. About 75 percent of American women receive mammograms every year or two after the age of 40, she said, while about 85 percent of women get Pap smears to test for cervical cancer.
The screening rates for colorectal cancer are much lower, perhaps around a third of women, she said.
The new review, published in the May 1 issue of the journalCancer, examined 32 studies looking at breast cancer (10 studies), cervical cancer (14) and colorectal cancer (eight studies). The studies typically defined obese women as those having a body mass index [BMI, a ratio of weight to height] of 30 or above. That means they were more than merely overweight as defined by national guidelines.
Overall, obese women were 10 percent to 40 percent less likely to be screened for breast and cervical cancer compared to other women, Cohen said. Black women, however, seemed to be much less affected by obesity when it came to the screenings.
There are many theories why heavier women might be less likely to undergo health screenings, Cohen said. "It may be related to patients' emotional barriers, things like embarrassment and fear of being weighed. It may be provider-bias, physicians having a bias against obese patients. And [obese women] have other health-care needs, like dealing with high cholesterol."
Another possibility is that medical equipment may not be sized properly to accommodate larger patients, Cohen said. "None of this has been studied in any quantitative way," she added.
Dr. Massimo Cristofanilli, an associate professor in the department of breast medical oncology at the University of Texas M.D. Anderson Cancer Center in Houston, said another possibility was that "women with low-incomes choose high-caloric foods and have difficulty in being particularly careful with their lifestyle. They may also be largely uninsured and have minimal access to screening programs."
"We should recognize that prevention of obesity is a critical issue," Cristofanilli added. "Education about a healthy lifestyle should start at school and continue through media and in the family."
To calculate your BMI, visit the U.S. National Heart, Lung, and Blood Institute.
SOURCES: Sarah S. Cohen, graduate student, department of epidemiology, University of North Carolina at Chapel Hill; Massimo Cristofanilli, M.D., associate professor, department of breast medical oncology, University of Texas M.D. Anderson Cancer Center, Houston; May 1, 2008,Cancer
Source : http://www.washingtonpost.com/wp-dyn/content/article/2008/03/24/AR2008032400950.html