Higher sTIL level was also associated with age (< 50 years), race/ethnicity (black), histologic type (invasive ductal carcinoma), and histologic grade (grade 3) in the ER/PR positive group without NACT, and with age (< 50 years) in the HER2 group without NACT (Additional file 1, Tables S1 and S3). Here, STIL is linked to invasive ductal breast carcinoma.