# Single-cell sequencing reveals the tumor immune microenvironment in thyroid cancer: a narrow review

## TL;DR

This review uses single-cell sequencing to map immune changes in thyroid cancer, showing how immune responses evolve from active to exhausted as the cancer becomes more aggressive.

## Contribution

The paper introduces a single-cell approach to reveal differentiation-dependent immune microenvironment remodeling in thyroid carcinomas.

## Key findings

- PTC shows coexistence of immune activation and suppression, PDTC exhibits immune exclusion, and ATC demonstrates terminal immune exhaustion.
- Single-cell analysis uncovers cellular heterogeneity and immune crosstalk masked in bulk data.
- Findings support precision immunotherapy strategies tailored to thyroid cancer differentiation stages.

## Abstract

The immune microenvironment profoundly shapes the progression and therapeutic response of thyroid carcinoma. Through comprehensive analysis of single-cell RNA sequencing data, this review delineates the immune landscapes of papillary thyroid carcinoma (PTC), poorly differentiated thyroid carcinomas (PDTC), and anaplastic thyroid carcinomas (ATC), revealing a differentiation dependent trajectory of tumor immune microenvironment remodeling—from immune activation suppression coexistence in PTC, to immune exclusion in PDTC, and terminal exhaustion in ATC. This single-cell based approach enables high resolution dissection of cellular heterogeneity, immune crosstalk, and spatial organization that are often masked in bulk analyses. Such insights provide a scientific basis for precision immunotherapy, offering guidance for differentiation tailored strategies to overcome immune escape and improve clinical outcomes in thyroid cancer.

Diagram titled “Evolution of TIME” showing three stages of tumor microenvironments: “immune active” with various immune cells around PTC cell, “immune cold” with fewer cells around PDTC cell, and “immune suppressive” with minimal immune activity surrounding ATC cell. Below, mutations and cell types are noted: BRAF/RAS, TERT for PTC; TERT, TP53, PI3K/AKT for PDTC; TP53, CDKN2A/B for ATC, with a progression arrow.