Breast Cancer--Early Detection Matters
Do you believe the authors of an European study who are asserting: "while screening may reduce cervical and colorectal cancer mortality, it's not so for breast cancer"? [British Medical Journal [BMJ] July 28, 2011]
Neither do I.
According to an August 3rd, 2011 [last accessed 8/7/11] Medscape editorial by Fran Lowry. The "conclusions of the BMJ study authors have little bearing on, or resemblance to, screening in the United States. Improvements in therapy have, likely, played a role in the decrease in breast cancer deaths, but therapy cannot cure advanced cancers. Early detection via mammography is clearly the major reason for the decrease in deaths in the United States." [American College of Radiology (ACR)]
A review, written mostly for general surgeons, supports screening. However, the sensitivity of screening mammography can be as low as 70% in women under 50 years of age, while over 50 it seems to be sensitive enough to reduce mortality by up to 1/3. Of course, it is problematic that there are many false-positives. As always, the risk must be compared to the benefit of these and other "standard" procedures. The Review also questions many interventions not the least of which is radical mastectomies. Other salient points from the article include, but certainly are not limited to: The main risk factors being age, race, previous biopsy results, age at menarche, age at first live birth, and first-degree relatives with breast cancer – see https://www.cancer.gov/bcrisktool/; chemo prevention for certain conditions; known genetic mutations (which are found in 5% of women with familial breast cancer).
Before leaving this excellent review, an historically relevant point: a 1971 study failed to show a survival, disease-free or distant-disease-free difference; that brought the era of radical mastectomy to an end.
NeumayerLA. (Dept. Surgery, Huntsman Cancer Hospital, University of Utah). "Breast Cancer:A review for the General Surgeon." JAMASurg.2013;148(10):971-980 Pub online August 28, 2013. doi:10.1001/jamasurg.2013.3393.
Full guidelines are available on the National Comprehensive Cancer Network website. Also, see the US Preventive Services Task Force Guidelines published in 2009, and, because they differ, those recommended by the American Cancer Society.
Not the Final Word....
How effective is screening mammography? If you screen a thousand 50-year-old American women every year for 10 years running, anywhere from 0.3 to 3.2 will avoid a breast cancer death. That statistic, however, is not proof of 'cause and effect', nor is it meant to reflect a cure rate. It is also important to recognize that about one half of these women will be burdened* by having "at least one false alarm and 3 to 14 will be overdiagnosed and treated needlessly. That may help some women choose whether to be screened or not. But it’s still not very precise, and it doesn’t answer the fundamental question: Now that treatment is so much better, how much benefit does screening actually provide? What we need is a clinical trial in the current treatment era... Then there is the problem of overdiagnosis: the detection of a 'cancer' that was not destined to ever cause problems. Overdiagnosis is what leads to overtreatment. A decade ago doctors debated whether this problem existed in breast cancer. Now the debate is about how often it occurs."
* Referencing pain and discomfort is a Research Letter, pub. in JAMA Jan. 1, 2014. "Pain at 12 Months After Surgery for Breast Cancer." JAMA 2014;311(1):90-92. doi:10.1001/jama.2013.278795.
H. Gilbert Welch..+ "Breast Cancer Screenings: What We Still Don’t Know." NY Times, (Op-Ed): Dec. 29, 2013 +Dartmouth Professor of Med. and an author of “Overdiagnosed: Making People Sick in the Pursuit of Health” with Lisa Schwartz and Steve Woloshin
An August 20th, 2015 JAMA Oncology article, “Breast Cancer Mortality After a Diagnosis of Ductal Carcinoma In Situ,” looked at U.S. government data on more than 100,000 women diagnosed from 1988 to 2011 with an early, localized lesion called "ductal carcinoma in situ” (DCIS). A cogent interpretation of this "discovery" by Alice Park of the NY Times is that “overall a diagnosis of DCIS was associated with a higher risk — 3% — of dying of breast cancer in 20 years compared to women who didn’t have the cancer,” with the risk being “highest for younger women (diagnosed before age 35) and for black women.” However, “when the researchers looked more carefully at the women with DCIS, their rates of breast cancer recurrence and their death rates, they found that those getting surgery and radiation or just surgery did indeed lower their risk of getting a recurrent cancer, but did not reduce their risk of dying from breast cancer.”
See, also in the NY Times, a must read excerpt, "Overdiagnosed."
Welch HG, Passow HJ. "Quantifying the Benefits and Harms of Screening Mammography." JAMA Intern Med. Pub. online December 30, 2013. doi:10.1001/jamainternmed.2013.13635 [Multi-pages and 32 references]