Obesity and breast cancer screening

Abstract

Background: Compared to normal weight women, women with obesity have higher mortality from breast cancer but are less often screened.

Objectives: To examine the relation between mammography use and weight category and to examine the influence of race, illness burden, and other factors on this relationship.

Design and setting: The 1998 National Health Interview Survey, a U.S. civilian population-based survey.

Participants: Five thousand, two hundred, and seventy-seven women ages 50 to 75 years who responded to the Sample Adult and Prevention questionnaires.

Measurements: Mammogram use in the preceding 2 years.

Results: Among 5277 eligible women, 72% reported mammography use. The rate was 74% among white women and 70% among black women. Among white women, mammogram use was lowest in women with a body mass index (BMI) greater than 35 kg/m(2) (64% to 67%). After adjusting for sociodemographic factors, health care access, medical conditions, hospitalizations, and mobility status, higher BMI was associated with lower screening among white women, P =.02 for trend; the relative risk (RR) for screening in moderately obese white women (BMI, 35 to 40 kg/m(2)) was 0.83 (95% confidence interval [CI], 0.68 to 0.96) compared to normal weight white women. Compared to normal weight black women, mammography use was similar or higher in overweight (BMI, 25 to 30 kg/m(2); RR, 1.19; 95% CI, 1.01 to 1.32), mildly obese (BMI, 30 to 35 kg/m(2); RR, 1.22; 95% CI, 0.98 to 1.39), and moderately obese black women (RR, 1.37; 95% CI, 1.37 to 1.50) after adjustment. The P value for the race-BMI interaction was.001. Results for white and black women were unchanged after additional adjustment for psychological functioning and health habits.

Conclusion: Among white women, those with higher BMI were less likely to undergo breast cancer screening than normal weight women. This relationship was not seen in black women. Our findings were not explained by differences in sociodemographic factors, health care access, illness burden, or health habits. More research is needed to determine the reasons for these disparities so that appropriate efforts can be made to improve screening.

FIGURE 1

Influence of different factors on the relationship between BMI and mammography use among white women. ^** Normal weight women served as the reference group with a relative risk of 1.00. ^† Model 1 was adjusted for sociodemographic factors, health care access, and general health status. ^‡ Model 2 was adjusted for factors in model 1 and medical conditions, hospitalizations, and mobility status. ^§ Model 3 was adjusted for factors in model 2 and proxy for psychological functioning. ^|| Model 4 was adjusted for factors in model 3 and health habits (tobacco use, physical activity, and alcohol use).

FIGURE 2

Influence of different factors on the relationship between BMI and mammography use among black women.^** Normal weight black women served as the reference group with a relative risk of 1.00. ^† Model 1 was adjusted for sociodemographic factors, health care access, and general health status. ^‡ Model 2 was adjusted for factors in model 1 and medical conditions, hospitalizations, and mobility status. ^§ Model 3 was adjusted for factors in model 2 and proxy for psychological functioning. ^|| Model 4 was adjusted for factors in model 3 and health habits (tobacco use, physical activity, and alcohol use).

FIGURE 3

Mammogram use among black and white women by weight category compared to normal weight white women.^* Normal weight white women served as the reference group. Analyses adjusted for sociodemographic factors, health care access, general health status, medical conditions, hospitalizations, and mobility status (model 2).