Percentage of tumor-infiltrating lymphocytes after chemoradiation therapy for locally advanced esophageal squamous cell carcinoma: a biomarker for pathological response rates and cancer-specific survival?

Both the innate and adaptive immune systems play a central role in the surveillance and control of neoplasia. A source of much recent attention, tumor infiltrating lymphocytes (TILs) are a population of T-cells, which have a greater degree of immunological reactivity against neoplastic cells, as compared with circulating (non-tumor infiltrating) lymphocytes. Given the key role that they play, TILs have been explored as prognostic biomarkers for a number of solid organ malignancies, including breast cancer (1), head and neck cancers (2), melanoma (3), colorectal cancer (4), non-small cell lung cancer (5), malignant pleural mesothelioma (6), and esophageal cancer (7).