Earlier Breast Cancer Screening Benefits Women with Childhood Cancer
About 30% of women who received chest radiotherapy as children develop breast cancer before reaching their fiftieth birthday. This cancer diagnosis rate is comparable to the rate of breast cancer in women with BRCA mutations. Of even greater consequence, women who received childhood chest radiotherapy have a 10%-11% of dying from breast cancer.
Few studies exist among these childhood cancer survivors. Clinicians needed to assess the risks, benefits, and costs of more frequent breast cancer screenings for these patients. A new study, led by Jennifer Yeh of Boston Children’s Hospital and Lisa Diller, M.D, of Boston Children’s Cancer and Blood Disorders Center, provides guidance for these childhood cancer survivors. The study was published in July 2020 in the Annals of Internal Medicine.
New Study Provides Insights
The National Health Institutes (NIH) and the American Cancer Society (ACS) underwrote this study. It looks at the harm-benefit ratios in different stimulation models. This study provides significant guidance to clinicians in estimating the harm-benefit ratio for women who are childhood survivors of Hodgkin and non-Hodgkin lymphoma or lung metastases.
While randomized trials are regarded as the “benchmark,” researchers find that trials are not realistic in rare, high-risk groups, including childhood cancer survivors. Study leader, Jennifer M. Yeh, Ph.D. from the Division of General Pediatrics at Boston Children’s Hospital, realized that combining relevant data from two models could yield comparable results to a trial.
Collaborators utilized two breast cancer simulation models. The researchers adjusted these models using data from the Childhood Cancer Survivor Study (CCSS) and the Cancer Intervention and Surveillance Modeling Network (CISNET). The CCSS examines trends and outcomes for over 24,000 childhood and adolescent cancer survivors, diagnosed between 1970 and 1999. The Cancer Intervention and Surveillance Modeling Network (CISNET) includes a group of National Cancer Institute examiners who study the impact of screening, prevention, and treatment on cancer rates and deaths.
Researchers simulated three annual screening options:
- No early screening
- Breast magnetic resonance imaging (MRI) only, beginning at age 25, 30, or 35
- Breast MRI along with mammography, beginning at age 25, 30, or 35
The model assumed that these women would continue annual screening until they reached 74. The researchers postulated that any woman diagnosed with breast cancer got the recommended treatment available at the time.
Study Results Offer Reassuring Data
The results of the study reinforce the Children’s Oncology Group (COG) recommendation. Their recommendation is clear and simple. The Children’s Oncology Group currently suggests the combination of annual mammography and breast MRI, beginning at age 25.
A combination of both breast MRI and mammography, beginning at age 25, reduced deaths by an estimated 56-to-71 percent. A breast MRI alone cut deaths by 56 to 62 percent.
The downside for beginning screening at 25 is the risk of more false-positives. False-positives may prompt a breast biopsy with benign results. The researchers estimate that an average survivor, screened with both MRI and mammography, would encounter 4 or 5 false positives and 1 or 2 breast biopsies.
Considering the emotional stress and costs associated with testing and follow-up biopsies, MRI plus mammography beginning at age 30 appears to be the most feasible strategy for women who had chest or mantle radiotherapy as a child or adolescent. Costs would not only be lower, but this subset of cohorts would be spared five years of stress.
For younger women who are particularly concerned over their risk of breast cancer, MRI-screening only is a prudent option.
Takeaways for the Clinician
Lisa Diller, M.D. (chief medical officer of the Dana-Farber/Boston Children’s Cancer and Blood Disorders Center and a co-author of this study) stresses that oncologists and OB/GYN practices must address the importance of breast cancer screening with their female childhood cancer survivors whose treatment included chest radiotherapy.
This study is reassuring to these women. Waiting until 30 is realistic and prudent. The study underscores the importance of breast cancer screening from 30 onwards with both mammography and breast MRI.