Trends in breast cancer incidence associated with reductions in the use of hormone replacement therapy

Hormone-Replacement Therapy and Its Association with Breast Cancer Subtypes: A Large Retrospective Cohort Study

Purpose

The study examined trends in breast cancer incidence, mammography testing rates, hormone-replacement therapy (HRT) use and breast cancer subtypes in a large Israeli health maintenance organization during 2000-2014.

Methods

Annual rates of mammography tests and HRTs use were analyzed in women age ≥45. Annual incidence rates of breast cancer were analyzed in women age ≥20. Estimated annual percentage changes were used to test changes in incidence rates. Invasive breast cancer subtypes were approximated by treatments received. We compared annual rates and duration of HRTs use between women diagnosed with breast cancer and those who were not, as well as HRT use between subtypes of invasive breast cancer.

Results

We identified 14,092 breast cancer cases (88% invasive, 12% in situ). The age-adjusted incidence rate of invasive breast cancer peaked in 2005, consistent with increased mammography screening that year, and decreased thereafter. HRT use decreased from 13.2% in 2002 to 4.6% in 2014. The subtypes distribution of 7771 patients diagnosed with invasive breast cancer during 2007-2014 was: luminal A and B without HER2 over-expression (HR+/HER2-), 69.7%; Luminal B with HER2 over-expression (HR+/HER2+), 8.9%; Hormone receptor-negative HER2 enriched (HR-/HER2+), 5.4%; triple negative (HR-/HER2-), 10.0%; unknown, 6.0%. Overall, in women age ≥45 diagnosed with invasive breast cancer, 76-86% did not have HRT exposure vs 14-24% who were current (within 1 year before the breast cancer diagnosis), recent (within 2-5 years), or past users (>5 years). Current/recent HRT use was statistically significantly higher in luminal vs non-luminal/unknown breast cancer subtypes (13.9% vs 8.9%, respectively; p < 0.001).

Conclusion

Our results show a decrease in breast cancer incidence that parallels the global and local decrease in HRT use. Yet, our results imply that current/recent HRT exposure may contribute to the incidence of luminal breast cancer tumors in particular. The magnitude of the effect supports findings from population-based studies.

A systematic review of non-hormonal treatments of vasomotor symptoms in climacteric and cancer patients

The cardinal climacteric symptoms of hot flushes and night sweats affect 24-93% of all women during the physiological transition from reproductive to post-reproductive life. Though efficacious, hormonal therapy and partial oestrogenic compounds are linked to a significant increase in breast cancer. Non-hormonal treatments are thus greatly appreciated.

This systematic review of published hormonal and non-hormonal treatments for climacteric, and breast and prostate cancer-associated hot flushes, examines clinical efficacy and therapy-related cancer risk modulation.

A PubMed search included literature up to June 19, 2014 without limits for initial dates or language, with the search terms, (hot flush* OR hot flash*) AND (clinical trial* OR clinical stud*) AND (randomi* OR observational) NOT review). Retrieved references identified further papers. The focus was on hot flushes; other symptoms (night sweats, irritability, etc.) were not specifically screened. Included were some 610 clinical studies where a measured effect of the intervention, intensity and severity were documented, and where patients received treatment of pharmaceutical quality. Only 147 of these references described studies with alternative non-hormonal treatments in post-menopausal women and in breast and prostate cancer survivors; these results are presented in Additional file 1.

The most effective hot flush treatment is oestrogenic hormones, or a combination of oestrogen and progestins, though benefits are partially outweighed by a significantly increased risk for breast cancer development.

This review illustrates that certain non-hormonal treatments, including selective serotonin reuptake inhibitors, gabapentin/pregabalin, and Cimicifuga racemosa extracts, show a positive risk-benefit ratio.

Key points

Several non-hormonal alternatives to hormonal therapy have been established and registered for the treatment of vasomotor climacteric symptoms in peri- and post-menopausal women.

There are indications that non-hormonal treatments are useful alternatives in patients with a history of breast and prostate cancer. However, confirmation by larger clinical trials is required.

Systematic review about breast cancer incidence in relation to hormone replacement therapy use

BACKGROUND

Several studies report a decrease in breast cancer incidence subsequent to the decrease in hormone replacement therapy (HRT) use. But its magnitude and the time-lag may vary between countries. This may reflect differences in populations, previous type and prevalence of HRT use and breast cancer screening.

AIM

To review systematically studies assessing the relation between breast cancer incidence and change of HRT use.

MATERIAL AND METHOD

Descriptive analysis of the methodology of the studies including design limitations and presence of confounding factors, data sources for breast cancer and HRT and regimens of HRT used.

RESULTS AND DISCUSSION

Eighteen articles were selected. Most studies were ecological and confounding factors such as mammography screening and changes in reproductive and lifestyle habits could not be excluded. Sources of data on breast cancer and HRT were heterogeneous and only few data on HRT regimens used were available. Most studies concluded that the decrease in HRT use during the last decade was probably associated with a decrease in breast cancer incidence, especially for women aged 50 years or more.

CONCLUSIONS

Data, mostly from epidemiological studies, suggest that the decrease in breast cancer incidence can be partly attributed to the drop in HRT use. Nevertheless, available studies are hampered by a number of limitations and it remains difficult to evaluate the exact impact of the drop in HRT use on the decrease in breast cancer incidence. Especially, the studies are seldom based on detailed individual data and do not provide information on regimens used, type of cancers and possible confounding factors.