TUESDAY, July 29, 2025 (HealthDay News) -- For women diagnosed with breast cancer at age 40 years or younger, the risk for isolated locoregional recurrence (LRR) is relatively low, according to a study published online July 23 in JAMA Surgery.Laura S. Dominici, M.D., from Brigham and Women's Hospital in Boston, and colleagues examined the long-term incidence of isolated LRR by molecular subtype in a multicenter prospective cohort study of women diagnosed with breast cancer at 40 years or younger from 2006 to 2016.The cohort included 1,135 women with stage I through III breast cancer, with a median follow-up of 10.1 years. Age at diagnosis was younger than 30 years, 31 to 35 years, and 36 to 40 years for 12.8, 28.0, and 59.2 percent of patients, respectively. The researchers identified 59 isolated local recurrences and four isolated regional recurrences (5.2 and 0.4 percent, respectively). The cumulative incidence of LRR at 10.1 years by subtype was 4.4, 4.7, 6.1, 2.2, and 6.5 percent for luminal A, luminal B, luminal ERBB2+, ERBB2+, and triple-negative, respectively. The cumulative incidence of LRR at 10.1 years by locoregional treatment type was 6.7, 6.5, and 2.4 percent after breast-conserving therapy, mastectomy without radiation, and mastectomy with radiation, respectively. In a multivariable analysis, mastectomy with radiation was associated with the lowest risk for LRR, but no differences were seen when examined by molecular subtype."Reassuringly, in this large contemporary study of women diagnosed with breast cancer at age 40 years and undertreated with modern local and systemic therapy, we observed overall low rates of isolated LRR in long-term follow-up, with no significant differences by local therapy strategy when compared within tumor subtype," the authors write. "Given the lengthy survivorship period for young women with breast cancer and increased numbers of young women being diagnosed, even longer-term follow-up is critical for understanding future LRR risk in these patients."Several authors disclosed ties to the biopharmaceutical industry.Abstract/Full Text (subscription or payment may be required)Editorial (subscription or payment may be required).Sign up for our weekly HealthDay newsletter