By James Kolter, M.D., FACOG
2015 has been a very good year for evidenced based medicine to dominate the breast cancer screening communities. This summer, the USPSTF reaffirmed their 2009 recommendations for normal risk women to limit mammogram screenings to the ages of 50-74 yrs. of age. The IARC World Health Organization consortium of experts from 16 countries (including the US) concluded that mammography be offered to women between 50 and 69 years of age. The American Cancer Society now recommends normal risk women begin mammograms at 45 years of age and at 55 years of age reduce screening to every 2 years. These recommendations took into account a large study from Canada that showed no improvement in breast cancer mortality resulted from mammogram screenings in women observed for 25 years. Also, the Bleyer et al study from the US found that over 30 years, there was very little improvement as a result of mammogram screenings. The study showed a very large increase in prevalence of DCIS as a result of mammography and yet this did not result in improvement in the occurrence of advanced (potentially lethal) breast cancer. In direct alignment with these data, this past year, we learned that DCIS serves as a risk factor for developing breast cancer but treating DCIS vigorously does not improve breast cancer survival.
This concept that less is best is further strengthened by a study I co-authored entitled Invasive Breast Cancer Incidence in 2,305,427 Screened Asymptomatic Women: Estimated Long Term Outcomes during Menopause Using a Systematic Review (ref and link below)
In this study, we found that the true risk of breast cancer for a woman who has not previously been diagnosed with breast cancer during her lifetime is significantly less than the 1 in 8 that our medical experts have been quoting. Our systematic review of 2,305,427 asymptomatic peri/postmenopausal women demonstrated that approximately 95% would not be diagnosed with an invasive breast cancer during 25 years of follow-up. The CDC figure of a 1 in 8 (12.5%) lifetime risk of breast cancer may be misleading when applied peri- and postmenopausal women without a prior diagnosis of breast cancer. The CDC developed its predictive models based only on studies of women with breast cancer obtained from cancer registries and attempted to work backward to predict outcome in all women. The newest published study worked forward using only screening reports of 2,305,427 women who were screened and followed but who did not have a prior diagnosis of breast cancer. Analyzing from cancer free women, at enrollment yielded a dramatically lower 25-year subsequent risk estimate. The widely advertised reasons for mammogram screenings appear to apply only to those patients with a prior personal history of breast cancer.
We have been learning that one of the principle harms of excess mammography is overdiagnosis that results in overtreatment of innocuous breast cancers, which never would become clinically significant if left undetected. This overtreatment increases the risk for other cancers developing in the future as well as a significant increase in cardiac mortality, emotional turmoil; complications from diagnostic and therapeutic surgical procedures; long-term aftereffects from medical treatments such as osteoporosis, cardiovascular damage; and disrupted sexual lives. Furthermore, this past year excess mammography has been shown to cost our country over $4 B yearly. Much of this cost is not completely covered by health insurance programs.
When a patient having a routine check-up asks what to make of all the conflicting information about early detection and mammography, she must learn that the chance that this cancer will affect her is much less than many think. We have learned that the benefits of mammography are much less than we had hoped it would be, and the harms of mammography are significant. This should be discussed with every patient so that she may make a truly informed decision about screening process. I believe most asymptomatic women, who know the facts about screening would reject annual mammograms and sleep better knowing of the reduced threat to her from breast cancer. Moreover, if we teach our patients the 5 things they can do to help prevent breast cancer, we would be making a real health contribution far greater than suggesting they go for mammograms in search of early stage disease they might have prevented or never been troubled by. These 5 are: to fight against weight gain with proper nutritional habits, engage in daily exercise, enjoy moderate but avoid excess alcohol and preempt vitamin D deficiencies with daily solar exposure of skin or a daily vitamin D3 supplement of 2000 IU. To a lesser degree avoiding an HRT regimen that contains any continuous combined synthetic progestin will also help. Since hormonal therapy that included synthetic progestin taken daily have shown a modest increase in incidence but sequential regimens have not shown these risks. Sequential progesterone opposed to daily estrogen has actually been suggested by some European studies as reducers of breast cancer.
References for all these can be sourced through our most recent study available on line at http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0128895
Cutler W, Bürki R, Kolter J, Chambliss C, Friedmann E, Hart K (2015) Invasive Breast Cancer Incidence in 2,305,427 Screened Asymptomatic Women: Estimated Long Term Outcomes during Menopause Using a Systematic Review. PLoS ONE 10(6): e0128895. doi:10.1371/journal.pone.0128895.