Background: Prospective studies in Western and Asian populations suggest that height is a risk factor for various cancers. However, few studies have explored potential confounding or effect modification of the association by other factors.
Methods: We examined the association between height measured at enrollment in 144,701 women participating in the Women's Health Initiative and risk of all cancers combined and cancer at 19 specific sites. Over a median follow-up of 12.0 years, 20,928 incident cancers were identified. We used Cox proportional hazards models to estimate HR and 95% confidence intervals (CI) per 10 cm increase in height, with adjustment for established risk factors. We also examined potential effect modification of the association with all cancer and specific cancers.
Results: Height was significantly positively associated with risk of all cancers (HR = 1.13; 95% CI, 1.11-1.16), as well as with cancers of the thyroid, rectum, kidney, endometrium, colorectum, colon, ovary, and breast, and with multiple myeloma and melanoma (range of HRs: 1.13 for breast cancer to 1.29 for multiple myeloma and thyroid cancer). These associations were generally insensitive to adjustment for confounders, and there was little evidence of effect modification.
Conclusions: This study confirms the positive association of height with risk of all cancers and a substantial number of cancer sites.
Impact: Identification of single-nucleotide polymorphisms associated both with height and with increased cancer risk may help elucidate the association.