Newswise — Hormone therapy, which is prescribed to women for relief of menopausal symptoms such hot flashes, night sweats and vaginal dryness, has recently seen a decline in popularity (and use) due to its link to an increased risk of breast and endometrial cancer. But City of Hope researchers have found that menopausal hormone therapy may actually lower the risk of B-cell non-Hodgkin lymphoma.

Sophia Wang, Ph.D., associate professor at City of Hope's Division of Cancer Etiology and first author of this study, will present the findings at the American Association for Cancer Research (AACR) annual meeting on Monday, April 7.

"The connection between lymphomas and menopausal hormone therapy use hinges on understanding the disease's biology and the window of susceptibility," Wang said. "Hormone therapy is of interest because the loss of estrogen coupled with aging in women result in decreased immune function, which can elevate risk of non-Hodgkin lymphoma."

For this study, Wang and her colleagues examined data from the Los Angeles Cancer Surveillance Program, comparing 685 postmenopausal women diagnosed with B-cell non-Hodgkin lymphoma to 685 postmenopausal women who did not have the disease and assessing their use of menopausal hormone therapy (either estrogen alone or estrogen with progestin, in either pill, patch, topical cream or injected forms).

After controlling for factors including age, race and socioeconomic status, Wang's team found that women who reported using any form of menopausal hormone therapy were approximately 30 percent less likely to be diagnosed with B-cell non-Hodgkin lymphoma, compared to women who reported never using menopausal hormone therapy.

Additional analysis showed that the risk reduction was even greater for women who initiated menopausal hormone therapy at a young age (45 years old or less) and used it for at least five years. This group was approximately 40 percent less likely to be diagnosed with a B-cell non-Hodgkin lymphoma compared to those who had never used hormone therapy.

Wang said these findings supported one part of her hypothesis, but further research will be needed to determine the exact biological mechanisms that might be linked to a lower non-Hodgkin lymphoma risk. These mechanisms could include supporting a healthy immune system or reducing inflammation.

Wang cautioned that the findings are preliminary and should not change current recommendations and guidelines for menopausal hormone therapy use.

Due to well-established evidence tying menopausal hormone therapy to elevated risks of breast and endometrial cancers, the American Cancer Society recommends that women considering, or using, this therapy to do so at the lowest effective dose for the shortest amount of time needed and that they discuss with their physicians about other treatments to alleviate menopausal symptoms.

Other researchers involved in this study include Jianning Luo, Wendy Cozen, D.O., M.P.H., Jane Sullivan-Halley, Yani Lu, Ph.D., Cynthia Quince, Teri Terrusa, James V. Lacey Jr., Ph.D., and Leslie Bernstein, Ph.D., from City of Hope's Division of Cancer Etiology.

Research reported in this publication was supported by the National Institutes of Health under grant numbers R01CA166219, P30CA033572 and P01CA017054. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.