Annual screening may reduce breast cancer deaths by half among childhood cancer survivors
CHICAGO — Initiating annual breast cancer screening at a younger age may prevent more than half of all breast cancer-related deaths among childhood cancer survivors treated with chest radiation, according to results of a comparative modeling study presented at this year’s ASCO Annual Meeting.
“Survivors of childhood cancer previously treated with chest radiation are at elevated risk for developing breast cancer,” Jennifer M. Yeh, PhD, assistant professor of pediatrics at Harvard Medical School and Boston Children’s Hospital, told HemOnc Today. “Studies suggest that 30% of these women will develop breast cancer by age 50 years — a risk similar to BRCA1 mutation carriers.”
For this reason, Yeh and colleagues sought to estimate the benefits and harms associated with secondary breast cancer screening among a cohort of childhood cancer survivors. Investigators simulated three screening strategies — annual mammography with MRI beginning at age 25 years, annual MRI starting at age 25 years, and biennial mammography starting at age 50 years.
Results showed that compared with no screening, annual mammography with MRI averted between 56% and 71% of breast cancer deaths. Between 56% and 62% of breast cancer deaths were averted with annual MRI, and between 23% and 25% of deaths were averted with biennial mammography.
HemOnc Today spoke with Yeh about the study, the challenges associated with screening these survivors, and what subsequent research will entail.
Question: What prompted this research?
Answer: Children’s Oncology Group (COG) guidelines for care of childhood cancer survivors recommend annual breast cancer screening with mammography and breast MRI. Adherence to these guidelines is low, which may be in part due to uncertain clinical benefits and potential harms from screening. Using decision modeling, we wanted to address this gap by estimating the potential benefits and harms associated with breast cancer screening among these high-risk survivors.
Q: How did you conduct the study?
A: Randomized clinical trials are often thought of as the ‘gold standard,’ but they are not always feasible for screening studies, especially of less common groups at risk, such as survivors of childhood cancer. Decision modeling is increasingly used by policymakers and those developing guidelines because these methods can provide important insight on the tradeoffs between clinical benefits and harms associated with screening. For example, modeling conducted by the NCI-funded Cancer Intervention and Surveillance Modeling Network (CISNET) has been used to inform the U.S. Preventive Services Task Force breast cancer screening guidelines for average-risk women. For the current study, we adapted two CISNET breast cancer simulation models using data from the NCI-sponsored Childhood Cancer Survivor Study to reflect the high breast cancer incidence and competing mortality risk among survivors. We then used these models to evaluate the clinical benefits and potential harms of various breast cancer screening strategies.
Q: What did you find ?
A: We estimated that annual screening of survivors with mammography and MRI starting at age 25 years, as currently recommended by COG, could avert about half of breast cancer deaths that could occur in the absence of screening. Harm-benefit ratios, such as number of benign biopsies per death averted, were no different from those estimated for average-risk women, based on USPSTF recommendations. In fact, some are more favorable, including number of false-positive screens or exams per death averted. Results were similar for screening with only MRI (no mammograms) starting at age 25 years.
Q: What are the challenges with screening for these survivors ?
A: Due to the toxicity of their childhood cancer treatment, survivors of childhood cancer often face health risks other than secondary breast cancer and have multiple health conditions to manage. Breast cancer screening may be associated with anxiety among these women. Making sure that young women who were treated with chest radiation are informed about their risk, as well as the estimated benefit of active screening, is challenging, as these women are sometimes no longer in the care of an oncologist. Our study underscores the importance of recommending breast cancer screening to these high-risk women and ensuring adherence to annual screening.
Q: Would a protocol like this ever be feasible enough to be implemented?
A: Yes, as annual breast cancer screening is currently recommended for other high-risk women.
Q: What is next for research?
A: Genetic markers of susceptibility have been identified for secondary breast cancer among childhood cancer survivors. Additionally, breast cancer risk may be lower among childhood cancer survivors diagnosed more recently as a result of changes in radiation dose and delivery. We are interested in using modeling to understand how this information can be used to refine screening guidelines. As childhood cancer survivors age, it also will be important to collect data on breast cancer among older survivors and to use that data to inform surveillance guidelines for survivors age 50 years and older.
Q: Is there anything else that you would like to mention ?
A: Breast cancer screening can avert about half of breast cancer deaths among childhood cancer survivors with a history of chest radiation. These survivors should initiate breast cancer screening early, and MRI is an important component of this screening. Primary care providers and oncologists who see these survivors should be sure to discuss breast cancer screening. – by Jennifer Southall
Yeh J, et al. Abstract 6525. Presented at: ASCO Annual Meeting; May 31-June 4, 2019; Chicago.
For more information:
Jennifer Yeh, PhD, can be reached at Boston Children’s Hospital, 300 Longwood Ave., Boston, MA 02115; email: firstname.lastname@example.org.
Disclosure: Yeh reports no relevant financial disclosures.