When should I start getting mammograms?

DEAR DOCTOR K:

I’m a 47-year-old woman who has never had a mammogram. Some experts recommend I get one, but others do not. I understand that the American Cancer Society recently updated its recommendations about breast cancer screening. Does it say I should have a mammogram? If so, which experts should I believe?

DEAR READER:

I’m surprised when people are bothered by medical experts having different opinions. Expert politicians, expert lawyers, expert architects — experts of all kinds disagree with each other all the time. Why? Because it is rare for the “truth” of any question to be clear beyond dispute.

The American Cancer Society (ACS) previously recommended that women begin getting mammograms at age 40. On the other hand, another expert group — the U.S. Preventive Services Task Force (USPSTF) — recommends that mammograms begin at age 50. That difference has confused many women. The good news is that the ACS recommendations published in October 2015 bring its advice closer to the advice given by the USPSTF. So it’s a bit less confusing.

Before I summarize where the two expert committees agree and where they differ, please understand that we’re talking about recommendations only for the average woman — not a woman at higher risk for breast cancer. Also, I’m talking about only these two expert committees, although there are several other expert committees with slightly different recommendations.

— WOMEN AGE 40-44. Neither the ACS nor the USPSTF now recommends regular mammography in this age range.

— WOMEN AGE 45-49. The ACS, but not the USPSTF, now recommends mammograms every year.

— WOMEN AGE 50-54. The ACS recommends mammograms every year, but the USPSTF recommends mammograms every two years.

— WOMEN AGE 55-74. Both guidelines recommend mammograms every two years (with one exception, mentioned next).

— LIFE EXPECTANCY LESS THAN 10 YEARS. The ACS no longer recommends regular screening mammograms if a woman has an illness or condition that gives her a life expectancy of less than 10 years.

— BREAST EXAMINATION BY THE DOCTOR. The ACS previously recommended that doctors perform regular physical examinations of a woman’s breasts to feel for suspicious lumps. Based on a lack of evidence that this finds cancer at an early and curable stage, it no longer recommends this practice.

Why do the experts have different opinions on these questions? For example, why does the ACS recommend a mammogram every year for women aged 50-54, whereas the USPSTF recommends it every two years? Because of new evidence. The ACS commissioned a large study involving over 15,000 women. They found that in premenopausal (but not postmenopausal) women, the tumors that were discovered during an every two-year mammogram program were larger and more advanced than those tumors discovered during an every-year program.

Indeed, if mammograms and examination of the breasts by the doctor might catch a cancer at an early, curable stage, why not simply do them? I’ll give you my answer to that question — and to the question you asked me — in tomorrow’s column.