Menopausal Hormone Therapy and Subsequent Risk of Specific Invasive Breast Cancer Subtypes in the California Teachers Study

Abstract

Background: Although it is well established that combined estrogen-progestin therapy (EPT) increases breast cancer risk, questions remain regarding the effect of different formulations of hormones, whether certain women are at particularly high risk, and whether risk varies by tumor subtype.Methods: We investigated hormone therapy (HT) use in relation to breast cancer risk in the California Teachers Study cohort; after a mean follow-up of 9.8 years, 2,857 invasive breast cancers were diagnosed.Results: Compared with women who had never used HT, women who reported 15 or more years of estrogen therapy (ET) use had a 19% greater risk of breast cancer (95% confidence interval, 1.03-1.37), whereas women using EPT for 15 or more years had an 83% greater risk (95% confidence interval, 1.48-2.26). Breast cancer risk was highest among women using continuous combined EPT regimens. Risks associated with EPT and ET use were increased with duration of HT use for women with a body mass index (BMI) of <29.9 kg/m

Postmenopausal hormone therapy and the risk of breast cancer in Norway

“…This is in agreement with evidence from some studies, [2][3][4]11,14,[33][34][35] but not with others that found a moderate increase in breast cancer risk with ET preparations. 5,10,13,21,[36][37][38][39] We found a moderate elevated risk in users of oral and transdermal estradiol, which is in agreement with results from Lyytinen et al 40 in Finland that found a similar increased risk of breast cancer for oral and transdermal users of estradiol. Use of vaginal estradiol is relatively common compared with oral and transdermal use.…”

“…These types of combined regimens were commonly used in the United States. 13 However, only 1% of women in our study population had combined prescriptions of progestin alone plus ET or EPT. Because this is not a typical prescription in Norway, and because of concern that this may or may not have been used concurrently, we excluded women prescribed progestin alone (ATC group G03D) from the analysis (see Fig.…”

“…39 Our findings of an increased risk of breast cancer for both continuous and sequential combined preparations of EPT are in agreement with previous studies. 3,10,13,15,[19][20][21] A study showed an increased risk of breast cancer for continuous compared with sequential preparations of estradiol-NETA. 27 We found a higher RR in continuous than in sequential preparations, but the differences were not significant.…”

“…17,18 There is less evidence as to whether risk differs between continuous and sequential EPT regimens, 3,10,13,15,[19][20][21] , or whether dose or route of administration matters. 10,21 Further, there is limited documentation on whether type of estrogen or progestin preparation matter, specifically whether EPT combinations containing androgenic progestin are associated with higher risk than other EPTs.…”

Triple‑negative breast cancer and its?association with obesity (Review)

“…As HT is widely used among patients who eventually develop breast cancer, it has been hypothesized that HT use may increase breast cancer risk (26). Although women with TNBC were less likely to have received HT, overweight women who had never received HT were at a higher risk of developing TNBC compared with overweight women who had been treated with HT.…”