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Many studies have examined the associations of body mass index (weight (kg)/height (m)2) with risk of various cancers. However, optimal scaling of weight for height may depend on the population studied. The authors used data from a large cohort study of women (Canadian National Breast Cancer Screening Study, 1980–2000; n = 89,835) to examine how the scaling of weight for height (W/Hx) influenced the association with risk of 19 different cancers. Cox proportional hazards models were used to estimate the hazard ratio for each cancer site with W/Hx, with x increasing from 0 to 3.0 by increments of 0.1. The correlation between weight and W/Hx decreased monotonically with increasing x, whereas W/Hx was minimally correlated with height when x = 1.4. W/Hx showed significant positive associations with postmenopausal breast cancer, endometrial cancer, kidney cancer, and lung cancer in never smokers. W/Hx was inversely associated with lung cancer in ever smokers. The value of x for which W/Hx produced the largest statistically significant hazard ratio ranged from 0.8 (endometrial cancer) to 1.7 (postmenopausal breast cancer). For lung cancer in ever smokers, the inverse association was statistically significant for all values of x. These findings suggest that the scaling of weight for height may vary depending on the cancer site and that optimal scaling may be considerably different from W/H2 or, alternatively, that a range of scaling should be considered when examining the association of body weight with risk of disease. [ABSTRACT FROM PUBLISHER]

Although the influence of body mass index on cancer risk has been intensively investigated, few epidemiologic studies have examined the association of adult height with risk of cancer. We assessed the association of height with risk of all cancer and of 19 site-specific cancers in the Canadian National Breast Screening Study, a prospective cohort of nearly 90,000 women. Weight and height were measured at enrollment, and information on reproductive and medical history as well as lifestyle exposures was obtained by means of questionnaire. After exclusions, 5,679 incident invasive cancers were identified among 88,256 women. We used Cox proportional hazards model to estimate hazard ratios (HRs) and 95% confidence intervals (95% CI) per 10 cm increase in height. All tests of statistical significance were two sided. All cancers combined and ten specific sites (colorectum, colon, premenopausal breast, postmenopausal breast, endometrium, ovary, kidney, thyroid, melanoma and leukemia) showed statistically significant positive associations with height. The HR for all cancers combined was 1.13 (95% CI: 1.08-1.18), and the magnitude of the associations for specific sites ranged from HR 1.11 (95% CI: 1.03-1.20) for postmenopausal breast cancer to HR 1.51 (95% CI: 1.27-1.80) for melanoma. Our study provides strong support for a positive association of adult height with risk of certain cancers. The underlying biological mechanisms are not clear but may differ by anatomic site., (Copyright © 2012 UICC.)