At MBCC, one presenter made the argument for screening mammography for all women starting at the age of 40, despite the controversy surrounding the topic.
Is 40 still the best age to start mammography screening?
Anyone who follows medical news in recent years knows that there has been a lot of controversy surrounding the topic of when women should start undergoing screening mammography for breast cancer. However, according to Daniel B. Kopans, MD, professor in the department of radiology at Harvard Medical School, there should be no controversy: Women should be encouraged to be screened every year starting at the age of 40.
Kopans recently discussed this viewpoint during his presentation, “The Never-Ending Controversy Over Screening Mammography: Enough is Enough,” at the 32nd Annual Miami Breast Cancer Conference, held February 26–28 in Miami Beach, Florida. According to Kopans, false arguments have been raised for more than 30 years in an effort to reduce access for women to screening mammography. During his presentation, Kopans addressed several of the “fictions” and “facts” associated with breast cancer screening.
Fictions associated with breast cancer screening have varied greatly during the last several decades. Some fictions from the 1970s included the idea that it was impossible to screen all women for breast cancer and that radiation from mammography would cause more cancers than will be cured. Kopans pointed out that data from the Breast Cancer Detection Demonstration Project proved that women could be screened efficiently and effectively, and that research has shown that radiation risk is age-related and decreases to unmeasurable levels by the age of 40.
In the 1990s, one of the concerns raised about breast cancer screening was that mammography would lead to false positives, and biopsies would permanently scar breast tissue. Kopans pointed out that research has shown that many false-positive cases are resolved with extra imaging exams, and that benign biopsies heal with little or no residual scarring.
Much of Kopans’s presentation focused on the many arguments made in the past, and present, against screening women aged 40 to 49 years, including arguments that breast tissue is too dense at these younger ages, that there is no benefit from screening at these younger ages, and that few cancers are diagnosed in this age group, meaning that attention is better focused on older women.
More recently, controversy surrounding this topic was sparked with the November 2009 release of the US Preventive Services Task Force (USPSTF) recommendations, which stated that women aged 40 to 49 should not undergo screening unless considered to be at high risk. Instead, screening should begin at age 50 and be done every other year. In contrast to these recommendations, the American Cancer Society recommends annual screening mammography in women starting at age 40.
“Waiting until the age of 50 and then screening every 2 years will result in the loss of tens of thousands of lives that could be saved by screening annually starting at the age of 40,” Kopans told Cancer Network. “Mammography screening is not the ultimate answer to breast cancer. It does not find all cancers and does not find all cancers early enough to cure everyone, but there is no universal cure on the horizon and screening is saving thousands of lives each year.”
According to Kopans, the National Cancer Institute in 1993, the American College of Physicians in 2007, and the USPSTF in 2009 all claimed that it is safe to delay regular screening until the age of 50 in women who are not at high risk. Kopans pointed out that the very models (CISNET) that the USPSTF used in its research show that screening women aged 40 years and older annually saves lives. “Using those models, as many as 100,000 women in their 30s in 2009 would die, unnecessarily, from breast cancer, if they followed the USPSTF guidelines instead of the American Cancer Society guidelines,” Kopans told Cancer Network.
The USPSTF guidelines also recommend screening women in their 40s based on their risk for developing cancer. However, data have shown that women with a genetic predisposition to breast cancer account for only about 10% of breast cancers diagnosed each year, with other risk factors accounting for an additional 15% of diagnoses. That means that about 75% of women with breast cancer have no identifiable risk factors. “If we exclude average-risk women, we will miss most cancers,” Kopans said.
According to Kopans, although there are widespread “fictions” associated with breast cancer screening, there are many truths associated with screening as well.
For example, a Pan-Canadian study by Coldman et al published in 2014 in the Journal of the National Cancer Institute showed that mammography screening programs in Canada significantly reduced breast cancer mortality. Specifically, an examination of breast screening programs looking at more than 2 million participants showed that the average breast cancer mortality in participants was 40% lower than expected in all provinces.
“The facts are that the death rate from breast cancer had been unchanged for 50 years until screening began in the mid 1980’s,” Kopans said. “Soon after, in 1990, the death rate began to drop and it has continued to fall as more and more women participate in screening. Each year there are more than 30% fewer women who die from breast cancer than would have, had screening not been available.”
Another truth, according to Kopans, is that randomized controlled trials have consistently shown a significant mortality reduction in women screened starting at age 40.
“As a consequence of screening and improvements in therapy, approximately 15,000 to 20,000 lives are being saved each year,” Kopans told Cancer Network. “Therapy has improved, but oncologists know that therapy saves the most lives by treating breast cancer earlier.”
As each new challenge to the use and efficacy of breast cancer screening has arisen over the last few decades, they have been addressed scientifically: Data support annual mammography starting at age 40.
“The oncology community has to stand up and say, ‘Enough is enough,’” Kopans said.