HER-2 overexpression is not associated with increased ipsilateral breast tumor recurrence in DCIS treated with breast-conserving surgery followed by radiotherapy.

BACKGROUND: We evaluated the clinical implications of human epidermal growth factor receptor (HER)-2 overexpression after adjuvant radiotherapy (RT) for ductal carcinoma in situ (DCIS).
METHODS: We reviewed 215 patients with DCIS who underwent breast-conserving surgery followed by RT. The association between HER-2 overexpression and ipsilateral breast tumor recurrence (IBTR) was evaluated.
RESULTS: HER-2 overexpression was associated with comedo-type architecture, high nuclear grade, and negative hormonal receptors. The median follow-up duration was 75 months. Sixteen patients experienced IBTR; seven as DCIS recurrence and nine as invasive recurrence. The IBTR rate was 11.4% at 10 years. There was no significant difference in IBTR according to HER-2 expression (P = 0.1764), neither in invasive nor DCIS recurrence. Time to recurrence was shorter in HER-2 positive tumors (P = 0.0697).
CONCLUSION: Adjuvant RT seems to counteract the negative effect of HER-2 overexpression in DCIS, while time to recurrence was relatively shorter.