Reproductive factors and risk of intermediate- or high-grade B-cell non-Hodgkin's lymphoma in women

Purpose: The incidence rates of non-Hodgkin's lymphoma (NHL) unrelated to h uman immunodeficiency virus infection are lower for women than for men; yet , few factors have been identified that may account for this difference in risk. NHL is difficult to study epidemiologically because this disorder rep resents a group of malignancies that differ in terms of morphologic present ation, immunologic features, genetic characteristics, prognosis, and etiolo gy. Patients and Methods: We conducted a population-based case-control study in women to determine whether reproductive factors or hormonal exposures migh t be related to the risk of high- or intermediate-grade B-cell NHL. We inte rviewed 177 female residents of Los Angeles County who were diagnosed with high- or intermediate-grade B-cell NHL between 1989 and 1992; each case pat ient was individually matched on age and race to a control subject who live d in her neighborhood. Results: Women who had used oral contraceptives had significantly lower ris k of intermediate- or high-grade NHL (multivariate odds ratio [OR] = 0.47; 95% confidence interval [CI], 0.26 to 0.86) than women who had never used t hese compounds. Among parous women, those who had used lactation suppressan ts (which contain high levels of estrogen) had significantly lower risk of NHL (multivariate OR = 0.50; 95% CI, 0.29 to 0.85) than unexposed women. po stmenopausal women had a somewhat greater risk of NHL than premenopausal wo men, whereas those postmenopausal women who had used hormone replacement th erapy (HRT) (primarily estrogen) had somewhat lower risk than those who had not used HRT. Conclusion: Exogenous estrogens seem to have a protective effect on the ris k of high- and intermediate-grade B-cell NHL. Although the mechanisms for s uch protection are not known, alterations in immune reactivity, cytokine ex pression, or B-cell modulation may play a role. J Clin Oncol 19:1381-1387. (C) 2001 by American Society of Clinical Oncology.