Risk for second primary breast cancer low in certain young breast cancer patients

Young breast cancer (BC) survivors (40 years or younger) without a pathogenic variant (PV) have a low risk for developing second primary BC (SPBC), according to a study published online April 11 in JAMA Oncology.

Kristen D. Brantley, Ph.D., M.P.H., from the Harvard T.H. Chan School of Public Health in Boston, and colleagues estimated the cumulative incidence of SPBC in women diagnosed with BC at or younger than age 40 years. Participants were enrolled in a prospective study including 1,297 women diagnosed with stage 0 to III BC.

The analyses included 685 women with stage 0 to III BC who underwent unilateral mastectomy or lumpectomy. The researchers found that 2.5% of patients developed an SPBC during a median follow-up of 10.0 years; two of these 17 patients had cancer in the ipsilateral breast after lumpectomy. There was a median of 4.2 years from primary BC diagnosis to SPBC. The 10-year risk for SPBC was 2.2% and 8.9% among women who did not carry a PV and for carriers of a PV, respectively, among 577 women who underwent genetic testing. The risk for SPBC was higher among PV carriers versus noncarriers in multivariate analyses (subdistribution hazard ratio, 5.27; 95% confidence interval, 1.43 to 19.43) and for women with primary in situ versus invasive BC (subdistribution hazard ratio, 5.61; 95% confidence interval, 1.52 to 20.70).

"The results of this cohort study suggest a relatively low five- and 10-year cumulative incidence of SPBC among patients aged 40 years or younger with BC who are noncarriers of PVs, emphasizing the importance of genetic testing among patients with BC," the authors write.

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