The clinical significance of tumor infiltrating lymphocytes in early breast cancer patients

Abstract

Background: Tumor infiltrating lymphocytes (TILs) are commonly detected in breast tumors but their clinical significance in breast cancer remains controversial. This study was conducted to assess the correlation between the level of TILs and other clinicopathologic parameters in early breast cancer patients. Material and Methods: The level of TILs was assessed by hematoxylin and eosin staining of primary tumor from 112 patients with stage I-III breast cancer. The level of TILs was analyzed in tumor nests, in stroma adjacent to tumor cells, and in stroma distant to tumor cells, and their relationship with clinicopathologic parameters was determined. The patients were divided into four subtypes for analyses, according to estrogen receptor (ER) and HER2 status: (1) ER+/HER2–, (2) ER+/HER2+, (3) ER-/HER2+, and (4) ER–/ HER2–. Results: The majority of the patients had an ER+/HER2− breast cancer (58.9%); 63 patients presented with a grade 3 tumor (56.3%). Twenty-nine percent of the patients had node-positive disease and 27% patients presented with tumors larger than 2 cm. Median level of TILs was 3%. Higher level of TILs (≥3%) was associated with tumor size ≥ 2cm, positive nodes and histologic grade ≥ 3, negative ER status and positive HER2 status (p = 0.029, 0.032, <0.001, <0.001 and 0.001). ER+/HER2− subtype had significantly lower level of TILs compared with other subtypes (p < 0.001). Conclusions: Our results demonstrated that higher level of TILs was associated with unfavorable clinicopathologic parameters. The level of TILs was low in ER+/HER2− subtype compared with other subtypes. The level of TILs could be potential prognostic parameter in breast cancer patients.