Selective Radiation Therapy for Ductal Carcinoma In Situ Following Breast-Conserving Surgery According to Age and Margin Width: Korean Radiation Oncology Group 11-04 and 16-02 Studies

The clinical significance of HER2 expression in DCIS

HER2 is an established prognostic and predictive marker for patients with invasive breast cancer. The clinical and biological significance of HER2 overexpression in patients with ductal carcinoma in situ (DCIS) remains poorly defined. DCIS is a heterogeneous disease and some patients with DCIS will not progress to invasive breast cancer. However, clinically significant recurrence rates have been reported after breast-conserving surgery for DCIS and approximately half of these cases will be life-threatening invasive recurrences. Since the incidence of DCIS is rising due to the widespread use of screening mammography, there is robust interest in selecting high-risk DCIS patients that may benefit from adjuvant therapies. Molecular prognostic and predictive models in early invasive breast cancer help clinicians identify patients that will benefit from chemotherapy. Molecular subtyping and profiling could also be useful in treating DCIS patients. According to current practice guidelines, HER2 testing is not recommended in DCIS patients. Nevertheless, evidence suggests that HER2-positive DCIS cases may be associated with adverse clinicopathological parameters and increased recurrence rates. This review summarizes the existing body of evidence linking HER2 expression and ipsilateral breast cancer recurrence in DCIS. HER2, as well as its correlation with other clinicopathological markers might be a useful prognostic and predictive marker, helping clinical decision-making in DCIS patients.

Adjuvant radiation therapy in small ductal carcinoma in situ

BACKGROUND

The objective of this study was to evaluate ipsilateral breast tumor recurrence (IBTR) rates in patients with small (≤1 cm) ductal carcinoma in situ (DCIS) who were followed up for more than 15 years.

METHODS

We identified 209 patients with primary small (≤1 cm) DCIS without invasion who received curative excision with and without adjuvant radiation therapy (RT) from 1996 to 2009. IBTR rates and prognostic factors in all patients were estimated by univariate and multivariate analyses.

RESULTS

With a median follow-up of 104 months, eight (53.3%) had DCIS recurrence and seven (46.7%) had recurrence of invasive ductal carcinoma. IBTR rate of all patients was 7.5% at 10 years and 12.1% at 15 years. In univariate analysis, age and subtypes were significant factors for IBTR. In multivariate analysis, resection margin, adjuvant RT, and endocrine therapy were significant factors for IBTR.

CONCLUSIONS

IBTR rate of small (≤1 cm) DCIS following excision with or without adjuvant RT was 12.1% at 15 years. Adjuvant RT and endocrine therapy were associated with lower IBTR rate in small DCIS.