Clinicopathological features and prognostic differences of ductal carcinoma in situ with ductal carcinoma in situ with microinvasion

Objective To determine the clinicopathological features and prognostic differences between ductal carcinoma in situ (DCIS) and ductal carcinoma in situ with microinvasion (DCIS-MI) of breast cancer. Methods A cohort of 489 female patients with surgically diagnosed DCIS (n=240, 49.1%) and DCIS-MI (n=249, 50.9%) in our hospital from January 2004 to December 2014 were recruited in this study. Their clinicopathological data and follow-up data were collected and analyzed for the differences in clinicopathological data, molecular subtypes and prognosis between DCIS and DCIS-MI patients. Results The age of initial diagnosis was usually younger than 55 years old (60.3%) in the 2 groups. Compared with DCIS patients, DCIS-MI patients had larger tumor size (P=0.034), higher histological grade (P < 0.05), and lower ER positive rate (P < 0.05); DCIS-MI patients had lower proportion of luminal-A type (54.6% vs 63.8%, P=0.040), while higher HER-2 over-expressed type (18.1% vs 9.2%, P=0.004). Statistical differences were seen in the distribution of molecular subtypes between the groups (Chi-square=8.921, P=0.030). The 5-year disease-free survival rate was 93.75% and 93.17% respectively in the DCIS and DCIS-MI patients, with no significant difference (Log-rank, Chi-square =0.074, P=0.785). Conclusion DCIS and DCIS-MI have different clinicopathological features and molecular subtype distribution, but no significant difference in prognosis, which indicates that they may be in different stages of breast cancer progression.