New Developments in Breast Cancer Screening and Treatment

Our goal in selecting these top articles about breast health in 2018 was to help identify literature that may change the clinical practice of women’s health for internists. We Identified articles by reviewing the high-impact medical and women’s health journals, national guidelines, ACP Journal Wise and NEJM Journal Watch. We have chosen to highlight new information about risk factors for the development of breast cancer (especially in breast cancer survivors), new information about breast cancer diagnosis, and finally, data about indications for chemotherapy use.

Risk Factors for Breast Cancer
More insight into cancer risks of oral contraceptives
Michels KA, Pfeiffer RM, Brinton LA, Trabert B. Modification of the associations between duration of oral contraceptive use and ovarian, endometrial, breast and colorectal cancers. JAMA Oncol 2018; 4:516-521.

What we know
Oral contraceptive (OC) use is common in reproductive-age women, but despite extensive study, uncertainties remain regarding the association between the use of hormonal contraception and the risk of breast cancer. Inconsistent findings from no elevation to an elevation of 20%-30% risk have been reported. Last year a study, reported in the NEJM, reported an increased risk of breast cancer with current OC use after as little as 5 years of use and remaining for at least 5 years discontinuation of OC. This was much stronger association of breast cancer with OC use than ad previously been reported and renewed concerns about the association between duration of OC use and a variety of cancers and reviewed their modification by family history and lifestyle factors.

Study Results
Data from the NIH-AARP Diet and Health Study cohort were analyzed. This is a large, prospective study of 3.5 million women enrolled between the age of 50 and 71. Information on the duration of OC use, demographics and characteristics, family history of cancer and lifestyle factors ( Smoking, weight, alcohol use, and exercise) was collected as baseline data before any cancer diagnosis was made. Participants were observed from enrollment until the first date of diagnosis of cancer, death, or end of study. Associations between OC use and each cancer of interest were calculated and then stratified by family history and life style factors. Forty percent of the cohort were OC users: 34,866 women used OCs for 1-4 years; 24,564 women used OCs for 5-9 years; and 18,962 women used OCs for more than 10 years (long-term use). Long-term use reduced ovarian cancer risk by 40% (hazard ratio [hr] 0.60p for trend <0.001). Risk reduction was noted with increasing among all lifestyle modifiers. Long-term use reduced endometrial cancer risk by 34% (HR 0.66,p for trend <0.001). The association was strongest among smokers and was not associated with reduction in woman with body mass indexes of 25 or less. There was no statistically significant association noted between OC use and breast cancer. Only long-term users who also smoked had a significant increase breast cancer risk of 21% (HR 1.21, 95% confidence interval [CI] 1.01-1.44). Family history was not predictive of OC use and breast cancer risk. There was no association between OC use and colon cancer.

What this changes or adds
This study confirms the previously noted reduction in ovarian and endometrial cancer in long-term use of OCs. There was no reduction in colon cancer risk even in long-term users of OCs. Mostly importantly, the null association between even long-term OC use and breast cancer, seen in women with family history of breast cancer, in this large, well-done cohort study in reassuring for both patients and providers. The one exception to this was an increased breast cancer risk in long-term users who are also smokers. This study helps to inform our counseling of patients about the risk and benefits of OC use and reminds us that all risks and benefits must be included in the counseling.

No increased risk of breast cancer after pregnancy in breast cancer survivors.

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