Substance abuse is frequently under-diagnosed among cancer patients. Alcoholism is a problem afflicting about 18% of the general population. This percentage is higher in hospitalized patients. Previous studies conducted on advanced cancer patients admitted in palliative care units have highlighted this problem only for a small percentage of cases. The objective of the study was to evaluate the incidence of alcoholism in patients with advanced cancer admitted to two Italian Oncology Units for active cancer treatment, using a recognized and validated assessment tool. To evaluate the incidence of alcoholism in cancer patients and its impact on symptoms, the CAGE questionnaire was completed by 117 patients in active anticancer treatment. The percentage of CAGE-positive patients was higher than previously detected in palliative settings and was associated to male sex and lower ESAS score. Alcoholism is widespread and under-diagnosed among patients undergoing active cancer treatment. Compared with other experience in palliative settings among European population, percentage of CAGE-positive patients was double. CAGE-positive patients were more likely to be male, with lower ESAS score. It is possible to hypothesize an effect of alcohol consumption on patients' perception of symptoms. This data has never been reported in the literature and will certainly need confirmation studies. The influence of alcoholism and of substance abuse in oncology, due to the multiple interconnections with metabolic pathways and drug-drug interactions, represents certainly an important aspect in the era of personalization of care, from palliative care to active cancer treatments.