On breast cancer screening. Guest post by Dr. Elaine Schattner

Mammography screening. Should you? Or shouldn’t you?

A few weeks ago, I received a letter in the mail from the clinic where I get my mammography. Rather than the expected ‘all is fine,’ the clinic was requesting that I call to schedule another screening due to abnormal findings. Not only was this not the way that I wanted to receive news that something might be wrong, but, I opened the letter at 4 pm on a Friday afternoon, giving me little time to get over the initial shock and then get on the phone to see if I could learn a bit more before the clinic closed for the weekend.

Mammography screening has been in the news quite a bit over the past year, with lines being drawn between experts who say that screening doesn’t save lives and women who want their mammograms regardless of the facts. I happen to fall on the latter side of the aisle and while I suffered a lot of anxiety before I had a second screening, not knowing would have been even worse. (FYI – it turned out fine.)

Recently, my friend Dr. Elaine Schattner, a trained oncologist, hematologist, educator and journalist, wrote about a new review that I believe that every woman should read before deciding whether or not to have a mammogram. It puts some of the controversy into perspective and also provides a much more balanced viewpoint on the risk-benefit ratio. And rather than reinvent the wheel, I asked Elaine if I could re-run the post on Flashfree. Please share it far and wide; it’s important.

With little fanfare, the NEJM pub­lished a feature on breast cancer screening in its Sept 15 issue. The article, like other “vignettes” in the Journal, opens with a clinical sce­nario. This time, it’s a 42 year old woman who is con­sid­ering first-​​time mammography.

The author, Dr. Ellen Warner, an oncol­ogist at the Uni­versity of Toronto, takes oppor­tunity to review updated evi­dence and rec­om­men­da­tions for screening women at average risk for the disease. She out­lines the problem:

Worldwide, breast cancer is now the most common cancer diag­nosed in women and is the leading cause of deaths from cancer among women, with approx­i­mately 1.3 million new cases and an esti­mated 458,000 deaths reported in 2008.(1)

On screening:

The decision to screen either a par­ticular pop­u­lation or a spe­cific patient for a disease involves weighing ben­efits against costs. In the case of breast-​​cancer screening, the most important ben­efits are a reduction in the risk of death and the number of life-​​years gained….

She breaks down the data for mam­mog­raphy by age groups:

For women between the ages of 50 to 69 the evi­dence is clear, she says. For those over 70, there are little data to support breast cancer screening. There’s a con­sensus that screening isn’t appro­priate for women with serious coex­isting ill­nesses and a life expectancy of less than 5–10 years.

For those between the ages of 40–49, Warner chal­lenges the revised 2009 USPSTF rec­om­men­da­tionson several counts. She cri­tiques those authors’ weighting of data from the Age trial of 161,000 women, empha­sizing the use of an anti­quated (single view) mam­mog­raphy tech­nique and flawed sta­tistics. She considers:

…However, this change in remains highly con­tro­versial,22, 23 espe­cially because of the greater number of years of life expectancy gained from pre­venting death from breast cancer in younger women. According to sta­tis­tical modeling,19 screening ini­tiated at the age of 40 years rather than 50 years would avert one addi­tional death from breast cancer per 1000 women screened, resulting in 33 life-​​years gained.”

What I like about Warner’s analysis, besides its extreme attention to details in the data, is that she’s not afraid to, at least implicitly, assign value to a pro­cedure that impacts a young person’s life expectancy rel­ative to that of an older person.

She goes on to con­sider digital mam­mog­raphy and the Digital Imaging Screening Trial (DMIST [NCT00008346]) results. For women under 50 years, digital mam­mog­raphy was sig­nif­i­cantly more sen­sitive than film (78% vs. 51%).

The article is long and detailed; I rec­ommend the full read including some helpful tables, with ref­er­ences to the major studies, and charts.

In con­cluding, the author, who admits receiving grant support from Amersham Health (a GE sub­sidiary), con­sulting fees from Bayer and lecture fees from AstraZeneca, returns to the hypo­thetical patient, and what might be said to a woman in her 40s who lacks an out­standing risk (such as a genetic dis­po­sition or strong family history):

…Mam­mog­raphy screening every 2 years will find two out of every three cancers in women her age, reduce her risk of death from breast cancer by 15%. There’s about a 40% chance that further imaging (such as a sonogram) will be rec­om­mended, and a 3% chance for biopsy with a benign finding.…

In my opinion (ES) this is key – that the chances of a false pos­itive leading to biopsy are only 3% for a woman in her 40s. If those biopsies are done in the radi­ology suite with a core needle, every 2 years for women of average risk, the costs of false pos­i­tives can be minimized.

About the author…Dr. Elaine Schattner is a trained oncol­ogist, hema­tol­ogist, edu­cator and jour­nalist who writes about med­icine. Her views on health care are informed by her expe­ri­ences as a patient with sco­l­iosis since childhood and other con­di­tions including breast cancer. Elaine is a Clinical Asso­ciate Pro­fessor of Med­icine at Weill Cornell Medical College in New York City where she teaches part-​​time. Her blog, Medical Lessons, is geared towards dissecting and providing commentary on how healthcare news is co­mu­ni­cated in order to foster learning and help bridge the gap between patients and doctors.