Long-term breast cancer risk post childhood cancer radiotherapy: data-driven screening recommendations for survivors

Modern radiotherapy techniques have significantly reduced radiation exposure to healthy tissues. This study analysed breast tissue radiation doses in a national pediatric radiotherapy database, explored the discrepancy between prescribed and actual doses and analysed shortcomings of current breast screening guidelines.

We analysed PediaRT database data on radiotherapy dose distributions for 5079 French childhood cancer patients (2013-present), focusing on photon therapy plans with available breast dose data (n = 428). Biological equivalent dose (BED) was calculated, and statistical analyses (t-tests, chi-square, Mann-Whitney U, Fisher's exact, and logistic regression) identified factors associated with breast dose exposure.

Among patients receiving supra-diaphragmatic radiotherapy, 99.3% had a prescribed dose >10 Gy, but 62.1% received a maximum dose greater than 10 Gy to at least one breast, and 25.5% received a mean dose greater than 10 Gy. As pediatric treatments often use fraction sizes <2 Gy, BED analysis revealed that 51.29% to 80.47% of patients prescribed >10 Gy received <10 Gy as minimal, maximal, or mean dose. These discrepancies suggest that current breast cancer screening guidelines, based on prescribed doses, may overestimate risk in survivors treated with modern techniques.

Our findings support a shift toward dose-specific screening recommendations based on actual tissue exposure. Relying solely on prescribed doses and fields may lead to unnecessary screenings and increased burden for patients.

This study is the first to assess actual breast tissue radiation doses using a national multicenter pediatric radiotherapy database. It highlights how current breast cancer screening guidelines based on prescribed doses may overestimate risk in survivors treated with modern radiotherapy techniques.