Elevated breast cancer risk in thyroid cancer survivors partly due to ¹³¹I treatment

Key clinical point: The risk of developing breast cancer (BC) was slightly elevated in women who received treatment for thyroid cancer, with increasing cumulative ¹³¹I activity being an important risk factor.

Major finding: Compared with the general population, the risk for BC was 1.5 times higher in thyroid cancer survivors (standardized incidence ratio 1.52; 95% CI 1.36-1.69). Although ¹³¹I treatment did not increase the risk for subsequent BC, the risk increased with increasing cumulative ¹³¹I activity (excess relative risk per 100 mCi 17%; 95% CI 2%-38%).

Study details : This pooled analysis included 8475 women who were treated for differentiated thyroid cancer, of which 62% received radiotherapy with ¹³¹I.

Disclosures: This study was supported by grants from the European Commission and other sources. The authors declared no conflicts of interest.

Source: Tran TVT et al. Breast cancer risk among thyroid cancer survivors and the role of I-131 treatment. Br J Cancer. 2022 (Oct 12). Doi: 10.1038/s41416-022-01982-5