Several new studies on breast cancer screening and treatment have been in the news this week. We bring you our unbiased, women’s-health-first take below.
Mammograms May Lead to Over-Diagnosis
The evidence continues to grow that mammography has significant harms as well as benefits. A Norwegian study that included nearly 40,000 women with invasive breast cancer found that 15 – 25 percent of breast cancers were over-diagnosed, meaning that these women received biopsies and treatment for breast cancer that would have either grown very slowly or not at all, and never would have caused symptoms or death from breast cancer. This translates to 6 to 10 women over-diagnosed for every 2500 screened via mammography.
The study, which looked specifically at invasive breast cancer, was published in the April 3, 2012 edition of the Annals of Internal Medicine. Because Norway introduced mammography in a staggered fashion over a nine year period, researchers were able to compare breast cancers diagnosed at the same period of time through mammography and those diagnosed once a tumor was palpable or produced other symptoms. There was reduction in late stage breast cancer in women who had mammography as well as those who didn’t. Researchers concluded that being aware of suspicious lumps was as effective as mammography without the risk of overtreatment that results from mammography findings. Since US women typically start mammography earlier than Norwegians it’s likely over diagnosis rates are even higher in the US.
This study gives us further evidence that we need to reframe how we work to end the breast cancer epidemic: early detection is not one’s best protection. All women and their health care providers should be made aware of the over-diagnosis issue and make screening and treatment decisions based on their medical history and individual values.
Breast Cancer News From the American Association of Cancer Research Conference
Long- Term Use of Hormone Therapy Linked to Higher Risk for Breast Cancer
A study done by Harvard researchers using data from the Nurses’ Health Study linked long-term use of estrogen plus progesterone and estrogen only hormone therapy with a higher risk of developing breast cancer. The study used follow-up data collected from 1980-2008 from postmenopausal women.
This National Cancer Institute (NCI) funded research saw an increased risk in developing breast cancer linked to estrogen and estrogen plus progesterone hormone therapy, but not an increased risk of dying from the disease. The researchers are currently looking into this aspect of their findings.
The researchers found that women who had taken estrogen plus progesterone for 10 – 14.9 years had an 88 percent higher breast cancer risk than women who did not use hormone therapy. , Breast cancer risk increased more than twofold for women who used estrogen plus progesterone for 15-19.9 years. For the estrogen only group, researchers found that less than 10 years of estrogen only hormone therapy saw a slight dip in breast cancer risk, but a 22 percent increased risk if used for 10 to 14.9 years, and 43 percent increased risk for 15-19.9 years of use. They also found a continued effect over time – the longer the use, the higher the risk.
This helps explain why new analysis of the Women’s Health Initiative data, published March 2012 in The Lancet, showed that estrogen therapy alone lowered risk – that study only analyzed date for women taking estrogen for under ten years.
Radiation Therapy May not Benefit Older Patients with A Certain Breast Cancer Subtype
Preliminary data from a randomized clinical trial of 769 women conducted in Canada indicates that women over age 60 with the Luminal A breast cancer subtype (defined as ER positive, PR positive, HER2 negative, and low Ki-67) had similar low relapse rates whether they were treated with tamoxifen plus breast radiation therapy or tamoxifen alone (6% vs. 4.3%). For all other breast cancer subtypes, local breast radiation was of benefit, significantly lowering the local relapse rate. This study shows another reason to have a full discussion with your health care provider to discuss what the right treatment is for you based on your specific medical history, cancer subtype and individual risk comfort level.