For the first time, the association of ALDH3A2 gene expression with PCa has been established; namely, a decrease in ALDH3A2 expression is associated with an unfavorable prognosis, which may be linked to a shift to the M2 phenotype, and, as a result, suppression of the immune function of the tumor microenvironment. The gene discussed is ALDH3A2; the disease is neoplasm.