Grade of ductal carcinoma in situ accompanying infiltrating ductal carcinoma as an independent prognostic factor

Background: Several studies about the relationship between IDC and DCIS have been reported, but no consensus has been reached regarding clinical characteristics and prognostic value.

Patients and methods: We reviewed the medical records of patients who underwent surgery for IDC between 2006 and 2008. DCIS adjacent to IDC was pathologically classified as either high-grade DCIS or non-high-grade DCIS.

Results: Among 1751 IDC patients within the study period, 1384 patients (79.0%) had concomitant DCIS. There was no survival difference between patients with pure IDC and those with IDC and concomitant DCIS. However, patients with high-grade DCIS had worse survival than did patients with non-high-grade DCIS or pure IDC (5-year recurrence-free survival rates for IDC with non-high-grade DCIS, pure IDC without DCIS, and IDC with high-grade DCIS were 97%, 93%, and 86%, respectively; P = .001). This tendency was maintained regardless of estrogen receptor status or histologic grade of IDC. In a Cox regression model, patients with IDC and accompanying high-grade DCIS had a 2.5-fold higher probability of local or distant relapse than did those with IDC and low-grade DCIS (hazard ratio, 2.51; 95% confidence interval, 1.12-5.64).

Conclusions: The prognosis of patients with invasive breast cancer differed according to the grade of concomitant adjacent DCIS. Accordingly, the grade of adjacent DCIS should be considered as a prognostic factor in the clinical management of patients with breast cancer. However, in our study, the follow-up periods were short to confirm prognostic effect. Further studies are needed.