Postmenopausal hormone therapy and non-Hodgkin lymphoma: a pooled analysis of InterLymph case–control studies

Non-Hodgkin lymphoma (NHL) subtypes, diffuse large B-cell (DLBCL) and follicular lymphoma (FL) have different sex ratios and are diagnosed at ages over 60 years; DLBCL is more common in men and diagnosed at older ages than FL, which occurs more among women. This analysis of postmenopausal women examines the relationship between postmenopausal hormone therapy and NHL. Self-reported use of postmenopausal hormone therapy from 2094 postmenopausal women with NHL and 2731 without were pooled across nine case–control studies (1983–2005) from North America, Europe and Japan. Study-specific odds ratios (OR) and 95% confidence intervals (CI) estimated using logistic regression were pooled using random-effects meta-analyses. Postmenopausal women who used hormone therapy were at decreased risk of NHL (pooled OR = 0.79, 95% CI 0.69–0.90). Risks were reduced when the age of starting was 50 years or older. There was no clear trend with number of years of use. Current users were at decreased risk while those stopping over 2 years before diagnosis were not. Having a hysterectomy or not did not affect the risk. Favourable effects were present for DLBCL (pooled OR = 0.66, 95% CI 0.54–0.80) and FL (pooled OR = 0.82, 95% CI 0.66–1.01). Postmenopausal hormone therapy, particularly used close to menopause, is associated with a decreased risk of NHL.