Intratumoral Immune Cell Densities Are Associated with Lung Adenocarcinoma Gene Alterations

Tumor-infiltrating immune cells affect lung cancer outcome. However, the factors that influence the composition and function of the tumor immune environment remain poorly defined and need investigation, particularly in the era of immunotherapy.

To determine whether the tumoral immune environment is related to lung adenocarcinoma mutations.

This retrospective cohort included 316 consecutive patients with lung adenocarcinoma (225 men; 258 smokers) studied from 2001 to 2005 in a single center. We investigated the association of densities of intratumoral mature dendritic cells (mDCs), CD8⁺ T cells, neutrophils, and macrophages with clinical and pathological variables and tumor cell mutation profiles obtained by next-generation sequencing.

In 282 tumors, we found 460 mutations, mainly in TP53 (59%), KRAS (40%), STK11 (24%), and EGFR (14%). Intratumoral CD8⁺ T-cell density was high in smokers (P = 0.02) and TP53-mutated tumors (P = 0.02) and low in BRAF-mutated tumors (P = 0.005). Intratumoral mDC density was high with low pathological tumor stage (P = 0.01) and low with STK11 mutation (P = 0.004). Intratumoral neutrophil density was high and low with BRAF mutation (P = 0.04) and EGFR mutation (P = 0.02), respectively. Intratumoral macrophage density was low with EGFR mutation (P = 0.01). Intratumoral CD8⁺ T-cell and mDC densities remained strong independent markers of overall survival (P = 0.001 and P = 0.02, respectively).

Intratumoral immune cell densities (mDCs, CD8⁺ T cells, neutrophils, macrophages) were significantly associated with molecular alterations in adenocarcinoma underlying the interactions between cancer cells and their microenvironment.