Expression of estrogen receptor, progesterone receptor, human epidermal growth factor receptor 2, and Ki-67 in ductal carcinoma in situ (DCIS) and DCIS with microinvasion

Ductal carcinoma in situ (DCIS) represents a heterogeneous disease in its histologic appearance and biological potential. Some women treated for DCIS subsequently develop invasive breast cancer. DCIS with microinvasion is considered as the interim stage in the progression from DCIS to invasive breast cancer. Analysis of the differences between DCIS and DCIS with microinvasion may aid in understanding the characteristic of DCIS with microinvasion and identifying biological factors determining progression of DCIS to invasive disease. Retrospective analysis of 219 cases between 2012 and 2018 was performed in our institution. The pathological results and axillary lymph nodes status were collected. Analysis of the expression of estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER-2), and Ki-67 in pure DCIS (164 cases), and DCIS with microinvasion (55 cases) using immunohistochemistry. DCIS with microinvasion had a higher nuclear grade (P < .001) and was more likely to have sentinel lymph node biopsy (SLNB) positivity (P = .039) than DCIS. Expression of ER, PR were significantly higher in DCIS compared with DCIS with microinvasion (P < .001, P < .001). While the expression of HER-2 in DCIS with microinvasion (56.4%) was significantly higher than in DCIS (36.6%, P = .01). Furthermore, DCIS with microinvasion was significantly more likely to have aggressive subtype (Triple-negative and HER2-enriched tumors, P = .005). Our results indicated that DCIS with microinvasion was different from pure DCIS in clinicopathologic characteristics and molecular alterations. It displayed a more aggressive biological nature than pure DCIS. It may be a distinct entity.