CD4 and breast carcinoma: CD4+ memory T cells (CD4+ MTCs) are closely associated with the prognosis in breast cancer (Deng et al., 2019), gastric cancer (Ning et al., 2020), lung adenocarcinoma (Choi and Na, 2018), and pancreatic cancer (Gu et al., 2020), but the role in colon adenocarcinoma (COAD) is unclear.