HT (Hormone Therapy) Duration, Type Affect Breast Cancer Risk

In our efforts to bring you news about Breast Cancer and its available treatments and causes, below please find an article regarding a study of the effects of Hormone Therapy on the development of Breast Cancer. We have duplicated the full article with a ‘translation’ of the study from BreastCancer.org. We hope this information is helpful to you and your loved ones. – Buttoned Up

“(MedPage Today) — Both the duration and composition of hormone therapy (HT) significantly influenced breast cancer risk in postmenopausal women, long-term follow-up in almost 3,000 women showed.

Fifteen years of combined estrogen-progestin therapy almost doubled the risk of breast cancer, whereas women who used only estrogen for the same amount of time had a 19% increase in risk, Tanmai Saxena, BS, of the University of Southern California in Los Angeles, and coauthors reported in Cancer Epidemiology, Biomarkers & Prevention.

Overweight and normal-weight women had a greater risk of breast cancer with increasing duration of HT, but not obese women.

The findings further refine breast cancer risk estimates for HT users and emphasize the need for personalized risk-benefit discussions with women who are considering therapy, the authors wrote.

Evidence linking combined HT and breast cancer reached a high-water mark in 2002 before publication of a report from the Women’s Health Initiative (WHI) suggesting that the risks outweighed the benefits for cardioprotection (JAMA 2002; 288: 321-333). Following publication of the report, sales of estrogen-progestin combinations plummeted, the authors noted.

Despite the documented association between estrogen-progestin therapy and breast cancer, many clinicians continue to prescribe various hormone formulations for treatment of menopausal symptoms. As a result, further delineation of women at highest risk for HT-associated remains an ongoing need, the authors continued.

In particular, more information is needed to determine whether the number of days of progestin use affect breast cancer risk, and more specifically, whether continuous combined regimens differ from sequential regimens with respect to risk. Other unresolved issues relate to the influence of low BMI on breast cancer risk and relationships between HT and breast cancer subtype (such as estrogen-receptor positive versus negative) and triple-negative breast cancer.

To address areas of uncertainty, investigators reviewed data from the California Teachers Study, a prospective cohort study of women enrolled in the California State Teachers Retirement System. The analysis focused on 56,867 peri- and postmenopausal women followed from 1995 through 2006. During follow-up, 2,857 women developed pathologically confirmed invasive breast cancer.

As compared with nonusers, women who reported any history of HT use had a 40% greater risk of invasive breast cancer.

Women who had used unopposed estrogen for at least 15 years had a 19% greater risk of breast cancer, whereas use of combined estrogen-progestin therapy for 15 years or longer increased breast cancer risk by 83%. Trend analysis showed that increasing duration of estrogen therapy and combined hormonal therapy had a significant association breast cancer risk (P=0.0394, P<0.0001, respectively). The highest risk was observed in women who reported continuous (versus sequential) use of combined hormonal therapy. Analysis of hormone use by baseline BMI showed that increasing duration of unopposed estrogen therapy increased breast cancer risk in women with BMI of less than 25 (P=0.0038) and BMI 25-30 (P=0.0309), but not women with BMI greater than 30 (P=0.5690). A similar association pattern emerged from analysis of combined hormonal therapy, which significantly increased breast cancer risk in women with BMI less than 25 and 25-29 (P<0.0001 for BMI categories) but not for obese women (P=0.1105). Increasing duration of unopposed estrogen and estrogen-progestin combinations posed a significant risk of dual receptor-positive (ER+/PR+) breast cancer but not other receptor subtypes (P=0.0036, P<0.0001, respectively). Neither the formulation or duration of HT significantly affected the risk of triple-negative (ER-/PR-/HER2-) breast cancer. The authors cited several limitations to their study, including characterization of HT use at cohort entry only and missing data on HER2 status in some women. A recent scientific statement from the Endocrine Society suggested that the risks and benefits of initiating postmenopausal hormone therapy may vary depending on the age of the patient and the length of time since menopause. The task force developing the statement also concluded that estrogen/progestin hormone therapy did not cause breast cancer, but instead caused preexisting tumors to grow to a size where they became detectable. Saxena reported that he had no disclosures. Coauthor Christina A. Clarke disclosed that she has served as a plaintiff's witness in litigation related to HT. Primary source: Cancer Epidemiology, Biomarkers & Prevention Source reference: Saxena T et al. "Menopausal hormone therapy and subsequent risk of specific invasive breast cancer subtypes in the California Teachers Study" Cancer Epidemiol Biomarkers Prev 2010; DOI: 10.1158/1055-9965.EPI-10-0162.”

BREASTCANCER.ORG SAYS:

HT Duration, Type Affect Breast Cancer Risk

Very large studies have shown that using hormone replacement therapy (HRT) increases the risk of hormone-receptor-positive breast cancer. The results of the large study reviewed here offer the same conclusions:

• breast cancer risk goes up more with combination HRT (contains estrogen and progesterone) compared to estrogen-only HRT

• the longer HRT is used, the more breast cancer risk increases

The California Teachers Study kept track of the health of nearly 57,000 retired women teachers over 10 years. The type of any HRT used and how long HRT was used were part of the health information recorded. During the 10 years, 2,857 women were diagnosed with invasive breast cancer. The researchers wanted to see if HRT use affected whether the women were diagnosed with breast cancer.

The results showed that women who used any type of HRT were 40% more likely to be diagnosed with invasive breast cancer compared to women who never used HRT. Also, women who used combination HRT had a higher risk of invasive breast compared to women who used estrogen-only HRT:

• women who used combination HRT for 15 years or longer had an 83% increase in invasive breast cancer risk compared to women who didn’t use HRT

• women who used estrogen-only HRT for 15 years or longer had a 19% increase in invasive breast cancer risk compared to women who didn’t use HRT

The longer a woman used HRT, the greater her risk of developing invasive breast cancer. Still, other research has suggested that most of the increase in breast cancer risk from HRT is linked to the first few years of HRT use.

The researchers also found that HRT use increased invasive breast cancer risk in normal weight and overweight women, but not in obese women (BMI
http://www.breastcancer.org/tips/nutrition/after_treat/lose_weight/assess.jsp of 30 or higher). This was true no matter which type of HRT the women used. The reason for this result isn’t clear.

Other research on HRT and risk has shown that HRT use increases the risk of hormone-receptor-positive breast cancer but not the risk of hormone-receptor-negative breast cancer. This study also confirms that result. Most breast cancers are hormone-receptor-positive.

Menopausal side effects can dramatically reduce quality of life for some women. These women have to weigh the benefits of HRT against the risks. If you’re having severe hot flashes or other menopausal side effects and are considering HRT, talk to your doctor about all of your options. Ask how you can minimize your breast cancer risk AND relieve your symptoms. Be sure to discuss the pros and cons of different types of HRT. This and other studies strongly suggest that estrogen-only HRT increases breast cancer risk less than combination HRT. If you do decide to take HRT, ask if you can take a lower-dose formula and try to take it for the shortest time possible.

Learn more about more about menopause and ways to manage side effects in the Breastcancer.org Managing Menopausal Symptoms http://www.breastcancer.org/tips/nutrition/after_treat/lose_weight/assess.jsp pages.