Intermediate Technical In the Industry Vocabulary Test

tumor infiltrating lymphocyte

Also written as: TIL — Tumor Infiltrating Lymphocyte

Immune cells that have migrated into tumor tissue and can influence cancer progression and treatment response.

Full Definition

Tumor infiltrating lymphocytes (TILs) are immune cells, primarily T cells, that have penetrated into the tumor microenvironment and surrounding stroma. The presence, density, and composition of TILs serve as important prognostic and predictive biomarkers across many cancer types. High TIL density generally indicates better prognosis and increased likelihood of response to immunotherapy. TILs can be quantified through histological assessment and are increasingly used in clinical decision-making, particularly in breast cancer and melanoma.

Usage

Usage note: Use tumor infiltrating lymphocyte (singular) or tumor infiltrating lymphocytes (plural); commonly abbreviated as TIL/TILs.

In Context

"Dense tumor infiltrating lymphocytes were observed throughout the invasive carcinoma, indicating favorable prognosis." — Pathology report
"TIL density greater than 20% predicts enhanced response to checkpoint inhibitor therapy." — Biomarker study protocol

Also known as

TIL infiltrating lymphocyte tumor-associated lymphocyte

Contrasted with

circulating lymphocyte peripheral lymphocyte

Don't confuse with

tumor-associated macrophage stromal lymphocyte lymph node

tumor heterogeneity ← Back to glossary Tumor Lysis Syndrome