Tumor-infiltrating myeloid cells (TIMs) are key regulators in tumor progression, but the similarity and distinction of their fundamental properties across different tumors remain elusive. Here, by performing a pan-cancer analysis of single myeloid cells from 210 patients across 15 human cancer types, we identified distinct features of TIMs across cancer types. Mast cells in nasopharyngeal cancer were found to be associated with better prognosis and exhibited an anti-tumor phenotype with a high ratio of TNF+/VEGFA+ cells. Systematic comparison between cDC1- and cDC2-derived LAMP3+ cDCs revealed their differences in transcription factors and external stimulus. Additionally, pro-angiogenic tumor-associated macrophages (TAMs) were characterized with diverse markers across different cancer types, and the composition of TIMs appeared to be associated with certain features of somatic mutations and gene expressions. Our results provide a systematic view of the highly heterogeneous TIMs and suggest future avenues for rational, targeted immunotherapies.

An atlas of cancer-associated T cells: The tumor microenvironment contains many different kinds of immune cells, the composition, function, and roles of which are unclear. Using single-cell RNA sequencing of T cells in 21 cancer types from more than 300 patients, Zheng et al . identified differences in transcript composition that could be used to catalog different T cell types (see the Perspective by van der Leun and Schumacher). These annotations identified the different roles of specific types of CD4 ⁺ and CD8 ⁺ T cells among the different tumor types. Some of these clusters revealed evidence for two developmental paths for T cells, one of which shows a trajectory toward the “exhausted” T cell state, knowledge of which may be useful in developing future cancer immunotherapies. —LMZ

Quiz Ref ID Gastric cancer is a common cancer and a leading cause of cancer-related deaths worldwide.^1-3 More than 90% of early gastric cancer is curative with surgical resection alone, and laparoscopic distal gastrectomy with limited lymphadenectomy is recommended for patients with early gastric cancer located in the middle or lower third of the stomach.^4-6 In contrast to early-stage gastric cancer, surgery for locally advanced gastric cancer (defined as T2-4aN0-3M0, corresponding to stages Ib to IIIc excluding T1 or T4b tumors; American Joint Committee on Cancer’s AJCC Cancer Staging Manual)⁷ is technically more challenging because dissection of D2 lymph nodes is required.⁴ The ability to perform adequate D2 lymphadenectomy using laparoscopic approaches is uncertain.