Breast Conserving Therapy Is a Safe Option for Women Under 40 Diagnosed With Breast Cancer

The incidence of breast cancer in young, premenopausal women has increased over time. For women above the age of 40, it is well-established that mastectomy and breast conserving therapy (BCT)-defined as lumpectomy plus radiation- confer similar outcomes in survival, albeit with a higher rate of local recurrence with BCT. The outcomes of mastectomy versus BCT in young women, however, remain unclear. In this study, we evaluate survival and recurrence risk in women under the age of 40 who have undergone mastectomy versus BCT.

We performed a retrospective review of all women diagnosed with breast cancer at the age of 40 or younger between 1995 and 2020 at Columbia University Irving Medical Center. Overall survival and recurrence-free survival were compared for patients undergoing mastectomy and BCT. Data were obtained from an established tumor registry and chart review; multivariate analysis was performed.

There were 414 women (average age 35 y) identified who were diagnosed with breast cancer at the age of 40 or younger. The median follow-up was 74 mo. In our cohort, 46% had a family history of breast cancer, 20% carried a BRCA gene pathogenic variant, 28% were nulliparous, and 12% presented with pregnancy-associated breast cancer. Distribution by subtype was: hormone receptor positive (HR+)/ human epidermal growth factor receptor negative (HER2-) in 59%, HER2+ in 21%, and HR-/HER2-/triple negative breast cancer in 20%. The stage at time of diagnosis was as follows: stage 0 (10%); stage 1 (24%); stage 2 (41%); stage 3 (14%), and stage 4 (11%). Neoadjuvant chemotherapy was administered to 42% of women per the standard of care, and 64% (n = 216) underwent mastectomy and 36% (n = 119) underwent BCT. Adjuvant radiation was administered to 68% of women (100% of BCT patients). The most common type of recurrence was distant metastasis (62%) compared with local and locoregional recurrence (38%). There was no statistically significant difference in 5-y overall survival (P = 0.24) and recurrence-free survival (P = 0.09) between BCT and mastectomy. On multivariate analysis , after controlling for age, stage, tumor subtype, and BRCA status, there was no difference in mortality (β = 0.018, P = 0.66) and recurrence (β = -0.069, P = 0.34) between patients who underwent BCT versus mastectomy at the last follow-up.

In our cohort with 5-y survival data, BCT is a safe option for women aged 40 y and under who are diagnosed with breast cancer. Despite no survival benefit, young women with breast cancer in our cohort underwent mastectomy more often than lumpectomy. Importantly, most recurrences were distant metastases, suggesting that local therapy choice is less relevant to outcome.