In a prospective epidemiological survey conducted in 34 European countries (European Cancer Anemia Survey (ECAS)) involving about 15,000 subjects diagnosed with solid or hematological tumors between 2001 and 2002, anemia (Hb <12 g/dL) was present in approximately 39% of patients at enrolment, and the overall prevalence increased to 67% during the 6 months’ follow-up [1]. The gene discussed is GSTM1; the disease is anemia (phenotype).