Early Screening May Curb Breast Cancer Deaths in Childhood Cancer Survivors

By Marilynn Larkin

July 07, 2020

NEW YORK (Reuters Health) - In childhood cancer survivors, starting annual magnetic resonance imaging (MRI) screening at ages 25-30 may reduce breast cancer deaths by at least 50%, researchers suggest.

"Survivors of childhood cancer previously treated with chest radiation are at high risk of dying from breast cancer," Dr. Jennifer Yeh of Boston Children's Hospital told Reuters Health by email. "Likewise, many primary care physicians who care for these high-risk women are unfamiliar with the risk or screening recommendations."

"Many survivors also lack access to or insurance coverage for MRI screening," she noted. "Our findings suggest that increasing the awareness of screening guidelines and ensuring access to screening can improve the long-term health of these survivors."

Dr. Yeh and colleagues developed two simulation models using the Childhood Cancer Survivor study and other published data to create a cohort of female survivors of childhood cancer with a history of chest radiotherapy.

The models evaluated three strategies: no screening; digital mammography with MRI screening starting at age 25 (current Children's Oncology Group recommendations), 30, or 35 and continuing to age 74; and MRI only starting at age 25, 30, or 35 and continuing to age 74.

Digital mammography alone was not considered because no current guideline recommends mammography alone as a surveillance strategy in this high-risk population.

As reported in Annals of Internal Medicine, the base-case analysis showed that lifetime breast cancer mortality risk without screening was 10% to 11% across models. Compared with no screening, starting at age 25, annual mammography with MRI averted the most deaths (56% to 71%), and annual MRI (without mammography) averted 56% to 62%.

Over their lifetime, 1,000 women would have 4,188 to 4,879 false-positive screenings and 1,340 to 1,561 benign biopsy results. Both screening strategies had the most screening tests, false-positive screening results, and benign biopsy results.

Specifically, for all strategies, the number of false-positive screening results per death averted ranged from 31 to 85 per 1,000 women and the number of benign biopsy results per death averted was 11 to 27 per 1,000 women across models.

These harm-benefit ratios were considerably lower - i.e., more favorable - than benchmarks for average-risk women undergoing United States Preventive Services Task Force-recommended biennial screening. Estimates of overdiagnosed cases per death averted were also lower than for average-risk benchmarks.

Costs of screening and diagnostic assessment of a positive screening result were based on U.S. 2018 Medicare reimbursement rates and published estimates.

For false-positive screening results, the team assumed that MRI findings led to 30% higher biopsy costs than mammography because of the higher costs for MRI guidance. For true positives, the assumption was that work-up costs were similar for both methods.

Cancer treatment costs varied by cancer stage and treatment phase and were based on SEER-Medicare data.

For an ICER threshold of less than $100,000 per quality-adjusted life-year gained, screening starting at age 30 years was preferable.

In a sensitivity analysis that assumed lower screening performance, the benefit of adding mammography to MRI increased in both models, although the preferred starting age remained unchanged.

The authors conclude, "Early initiation (at ages 25 to 30) of annual breast cancer screening with MRI, with or without mammography, might reduce breast cancer mortality by half or more in survivors of childhood cancer."

Dr. Denise Rokitka, Director of Pediatric, Adolescent Cancer Survivorship and of the Young Adult Program and Oncofertility Program at Roswell Park Comprehensive Cancer Center in Buffalo, New York, said the findings are "compelling and warrant further research in current survivors regarding the age to start breast cancer screening."

"There is a fair amount of anxiety in childhood cancer survivors and false positives over a lifetime (that) perhaps that could be reduced by starting screening at age 30," she told Reuters Health.

"With regards to use of MRI with or without mammography further research needs to be done," said Dr. Rokitka, who was not involved in the study. "The low risk of additional radiation from a mammography may continue to outweigh the benefit of additional imaging that can yield different results - i.e., different types of breast cancer can be found better on MRI versus mammogram and vice versa."

"At this time, I will continue to use both modalities for survivors of childhood cancer," she said. "However, this study does highlight some compelling arguments for potentially later screening and only use of MRI."

"For providers of survivors of childhood cancer, it is imperative that we empower patients to know their risks and to advocate for early screening," she stressed. "Not all childhood cancer survivors are followed by a survivorship clinic and therefore, we as pediatric oncologists need to ensure that we provide the best education for long term complications from their cancer therapy."

SOURCE: https://bit.ly/2VROVoF Annals of Internal Medicine, online July 6, 2020.