Anthropometric variables in relation to risk of breast cancer in middle-aged women.

BACKGROUND Many epidemiological studies have assessed the relationships between anthropometric variables and breast cancer risk. However, methodological approaches for analysing these factors differ appreciably. Also, age when maximum height is achieved has been identified as a potential risk factor for breast cancer in premenopausal women, but this issue has not been studied in postmenopausal women. METHODS The participants in this population-based case-control study were postmenopausal women 50-64 years of age from the general female population of western Washington State. It included 479 women with incident primary breast cancer and 435 controls. RESULTS This study found that: (i) women who gained over 70 pounds since age 18 had an increased risk of breast cancer relative to those who stayed within 10 pounds of their weight at age 18 (odds ratio [OR] = 2.7; 95% CI: 1.5-4.9), (ii) women with body mass indices (BMI) below what is considered healthy had a decreased risk (OR = 0.4; 95% CI: 0.2-1.1) while women with a BMI in the obese range had an increased risk of breast cancer (OR = 1.4; 95% CI: 1.0-2.1), and (iii) women who reached their maximum height at or after the age of 18 had a decreased risk of breast cancer compared to women who reached their maximum height at age 13 or younger (OR = 0.7; 95% CI: 0.5-1.0). CONCLUSIONS By examining various anthropometric variables using clinically relevant strata, a clearer picture of how these variables relate to postmenopausal breast cancer risk was developed. Similar to younger women, postmenopausal women who reached their maximum height at later ages had a decreased risk of breast cancer.