Impact of Age on Locoregional and Distant Recurrence After Mastectomy for Ductal Carcinoma In Situ With or Without Microinvasion.

Background: Locoregional recurrence (LRR) after breast-conserving surgery (BCS) for ductal carcinoma in situ (DCIS) is increased in young women. We examined the impact of age on LRR and distant disease after mastectomy for DCIS ± microinvasion.

Methods: We identified consecutive patients with DCIS ± microinvasion treated with mastectomy from 1995 to 2017. LRR was defined as recurrence at the ipsilateral chest wall or regional nodes.

Results: Overall, 3121 cases were identified, of which 421 (13.5%) had DCIS + microinvasion. Median age was 49 years and median follow-up was 6.4 years; 821 were followed for 10 or more years. Thirty-four LRRs were observed: 33 (97%) were invasive, and 23 (68%) were in the chest wall alone. Cumulative 10-year LRR incidence was 1.4%. Age < 50 years, high grade, and DCIS + microinvasion were associated with LRR (p ≤ 0.001); however, margin status was not (p = 0.14). Adjusting for grade and DCIS + microinvasion, age < 50 years (hazard ratio [HR] 14.7, 95% confidence interval [CI] 3.5-61.5; p < 0.001) was associated with LRR. Compared with women ≥ 50 years of age, women age < 40 years had the highest risk (HR 27.0, 95% CI 6.0-121), and women age 40-49 years had intermediate risk (HR 11.8, 95% CI 2.8-50.5). The cumulative 10-year LRR incidence was 4.2% for women < 40 years of age, 2.0% for women 40-49 years of age, and 0.2% for women ≥ 50 years of age. Women age < 40 years had a 10-year distant disease rate of 1.6% versus women age 40-49 years (0.7%) and women age ≥ 50 years (0.7%) (log-rank p = 0.051). Grade, DCIS + microinvasion, and margins were unassociated with distant disease.

Conclusions: LRR after mastectomy for DCIS ± microinvasion is uncommon, but is more frequent among women < 50 years of age, particularly in those < 40 years of age. The 10-year LRR rate in this youngest group remains low at 4.2%. Young age is an independent risk factor for LRR after BCS or mastectomy.