The infiltration of natural killer cells or macrophages into tumours was previously found to indicate a favourable prognosis (Takeo et al, 1986; Takanami et al, 2001), whereas the presence of tumour-infiltrating CD8+ T cells was not found to be a predictor of patient survival (Mori et al, 2000; Wakabayashi et al, 2003). The gene discussed is CD8A; the disease is neoplasm.