Prognostic Implications of Concurrent Ductal Carcinoma In Situ in Invasive Breast Cancer: an Observational Nested Cohort Study from a Regional Cancer Center in India.

Ductal Carcinoma In Situ (DCIS) is not an obligate precursor to invasive breast cancer and can exhibit variations in clinical presentation, genetics, biomarkers, and morphological features. There are contrasting views in literature with regard to prognostic significance of DCIS component in invasive cancer. Hence, this study aimed to evaluate how the co-occurrence of DCIS affects the prognosis of people with invasive breast cancer (IBC). A retrospective nested cohort observational study of patients with invasive breast cancer with and without DCIS component was conducted to compare the types of metastases developed on the subsequent follow-up, treatment details, event free survival and other histopathological parameters. There was a significant difference ( = 0.014) in the mean age at diagnosis between patients of IBC with concurrent DCIS (45 ± 11.18 years) and those who had IBC alone (53.24 ± 10.45 years). Invasive cancer with concurrent DCIS component tends to be more common in patients less than 50 years age group ( = 0.03). Majority (75.56%) of the patients were in post-menopausal stage. Patients with concurrent DCIS had higher frequencies of tumors of T1/ T2 stages and zero nodal status. Higher frequencies of local recurrence and visceral metastases were observed in patients with DCIS component compared to patients with IBC alone. Majority had received complete treatment. Longer event free survival was noted in patients with DCIS component compared to those with IBC alone. Our study demonstrated significant association of concurrent DCIS component with mean age at diagnosis in patients with invasive breast cancer. Although a trend towards favorable tumor profile was observed, larger prospective studies are required to enhance the statistical power of our findings. In view of its impact on clinical outcome, it is important to risk stratify invasive breast cancer based on the features of concurrent DCIS component.