Screening mammograms: One recommendation may not fit all

To date, official recommendations on when and how often a woman should have a screening mammogram, have been based on risk factors (such as age, a family history of breast cancer, a personal history of radiation to the chest), genetic testing (the BRCA test, for example), or troubling results from a previous biopsy. Race and ethnicity have not officially factored into the equation — yet.

Does race matter when it comes to screening mammograms?

A recent study by Harvard doctors at Massachusetts General Hospital reinforces prior data suggesting that race and ethnicity can be a separate risk factor for breast cancer, and should be taken into account when advising women on when and how often to have a screening mammogram.

The authors studied almost 40 years of data in a massive, publicly available US research information bank called the Surveillance, Epidemiology, and End Results (SEER) Program, and identified over 740,000 women ages 40 to 75 with breast cancer. They wanted to know if the age and stage at diagnosis differed by race.

It did. White women's breast cancers tend to occur in their 60s, with a peak around 65. However, black, Hispanic, and Asian women's breast cancers tended to occur in their 40s, with a peak around 48. In addition, a significantly higher proportion of black and Hispanic women have advanced cancer at the time of diagnosis, when compared to white and Asian women.

This fits with prior studies, including a separate analysis of data from SEER as well as the Center for Disease Control's National Program of Cancer Registries (NPCR). They found that non-Hispanic white women tend to have the least aggressive breast cancer type, while black women tend to have the most aggressive type, as well as more advanced disease at diagnosis.

Basically, there are reliable data to suggest that we take race and ethnicity into account when we counsel patients about when to start mammograms and how often to have them. While many doctors are aware of the data and are sharing this information with patients, it's not part of "official" guidelines.

So what are the official guidelines for screening mammograms?

Well…

Breast cancer screening has become an area of some controversy, with at least six different US organizations offering varying opinions, more or less in the same ballpark (give or take 10 years, that is). For the average woman without the risk factors listed above, the recommendations range from

Every woman over age 40 should have a mammogram every year, but, it's a shared decision-making process so talk about it first (American College of Obstetrics and Gynecology)

to

Start at age 45 and then every year until age 55, then every otheryear (American Cancer Society)

to

Start screening mammograms at age 50 and have them every other year (United States Preventive Services Task Force).

This variability seems confusing, but what is consistent is that all guidelines recommend a shared decision-making process. That means a woman should talk with her doctor to determine when to first have a screening mammogram, and how often she should have one.

Reasons a woman might not want to start screening mammograms at age 40

Apart from some awkwardness and discomfort, why wouldn't a woman want to start screening mammograms at age 40? Every screening test carries some risk, including unnecessary additional imaging and biopsies. The idea is that by starting screening later, the likelihood of catching cancer early isn't outweighed by the risks of screening. Many of my patients have gotten that dreaded callback after their mammogram: "We see something that may be cause for concern and need you to return for additional images." This is nerve-racking and involves additional radiation exposure. If the area is still worrisome, then a biopsy may be done. Most biopsies are negative, and even when positive, we don't know for sure that all low-grade, localized cancers are going to progress. We treat them when we find them for sure, but it's possible that not everyone will benefit from lumpectomy and radiation or mastectomy.

What do women need to know about screening mammograms?

Doctors should counsel women accurately about their risks and benefits for cancer screening, and while guidelines are helpful, they are only guidelines. We need to know where the guidelines came from, what data was used to create them, and — most importantly — what data were not used to create them. In the case of breast cancer screening, race and ethnicity have not yet been formally included in the existing guidelines, and women need to be aware of that and what it means for them.