Risk-Adapted Starting Ages Suggested for Breast Cancer Screening

By Anne Harding

November 23, 2019

NEW YORK (Reuters Health) - A new analysis in more than 5 million women has identified starting ages for breast cancer screening based on family history of the disease.

"This study using the largest datasets of its kind clearly answered the question: 'At what age should women with different family histories of breast cancer start screening?' We identified risk-based starting ages for breast cancer screening and provided a clear evidence-based guidance to clinicians and relatives of patients with breast cancer on when to start screening according to the level of risk,'" Dr. Elham Kharazmi of the National Center for Tumor Diseases in Heidelberg, Germany, told Reuters Health by email.

Most guidelines recommend that women start breast cancer screening at the same age, regardless of family history, Dr. Kharazmi and her colleagues note in JAMA Oncology, online November 14. Guidelines that do suggest an earlier start for higher-risk women "are largely based on expert opinion rather than empirical evidence," they add.

The authors looked at Swedish registry data on nearly 5.1 million women, including 118,953 who were diagnosed with invasive breast cancer, 102,751 of whom (86.4%) had no family history of breast cancer in first-degree or second-degree relatives.

For the general population, 10-year breast cancer risk was 1.1% at age 40, 1.8% at age 45 and 2.2% at 50, the authors found. Lifetime breast cancer risk for the 13.6% of women with family histories of breast cancer ranged from 11% to 23%, while it was 9.4% for the women with no family history of breast cancer.

With screening starting at age 50, the authors calculate that a woman with one second-degree relative (SDR) with breast cancer would reach the 2.2% 10-year breast cancer risk point at age 45, while women with one affected first-degree relative (FDR) would reach the 2.2% risk level at age 40.

Women with one affected FDR and additional SDRs with breast cancer reached this level of risk at age 38, while women with several affected FDRs did so at age 35.

The age when an FDR was diagnosed with breast cancer also affected the age at which women reached the screening-equivalent risk level.

Women with no family history of breast cancer reached general population screening level risk at age 52, the authors note. "Postponing screening for this group might represent substantial reductions in otherwise unnecessary mammograms and cost savings required for earlier screening initiation in high-risk women," they add.

"Overall, the results suggest that current screening guidelines do not sufficiently provide evidence-based recommendation on starting age of screening for women with a family history of breast cancer," Dr. Kharazmi said. "The American College of Radiology recommends starting ages of screening that are closest to the risk-adapted starting ages of screening calculated in this study, although differences still existed."

She added: "More studies that consider all known risk factors of breast cancer are warranted to be able to provide optimal personalized starting ages of breast cancer screening. We also aim to provide information on how many years later women with low risk of breast cancer (for example, women with more children or those who had their first child at age 20-25 years) could start screening than their peers in the general population, which would save resources for earlier screening of women with higher risk."

In an editorial accompanying the study, Dr. Gretchen L. Gierach and colleagues from the National Cancer Institute in Bethesda, Maryland, note that "assessment of the validity and clinical utility of this approach is necessary before considering its use in clinical practice."

While the authors validated the study internally, they add, "it is also essential to validate the robustness of their findings across diverse, independent populations."

SOURCE: https://bit.ly/2QBW6PH and https://bit.ly/2OymgAx

JAMA Oncol 2019.