ICOS and lung cancer: While some studies presented ICOS as a negative predictor of prognosis especially in FOXP3+ T‐regs cells, others demonstrated that higher ICOS expression was associated with better survival in colorectal cancer and lung cancer, when its expression is examined in the context of T‐helper (Th1)/cytotoxic T lymphocytes and in the context of higher CD3 expression rather than T‐regs [16, 26, 27, 28].