Candidate patients for cardiac surgery procedures with a history of malignancies and antitumour therapy or with an active cancer and on antineoplastic treatment are increasingly common in daily practice. Oncological therapy can lead to cardiovascular injury and, therefore, has the potential for impacting operative risks and surgical strategies. This means that a number of considerations are essential to take into account prior to cardiac surgery. These include the type of cancer, previous cardiotoxicity or concomitant antitumour therapy, reversibility or irreversibility of such complications, the interaction between cancer disease course and extracorporeal circulation, the need for associated surgery and the impact of cancer on early and long-term outcomes. Adequate preoperative evaluation of cardiovascular abnormalities potentially related to antineoplastic therapy and proper diagnostic workup of other conditions linked to the type of cancer (e.g. haematological disorders and lung dysfunction) are therefore of paramount importance for appropriate surgical decision-making. Careful evaluation of the association of cardiovascular disease to be treated and the prognosis of remitted or active cancer should be established to enhance the prediction of early, medium and long-term outcomes and for a more correctly informed patient. Furthermore, if the prognosis of operated patients appears unfavourable, then alternative therapeutic strategies can be applied without significant delay. The aim of this review is to give an overview of factors that should be considered in adult patients who are undergoing, or have undergone, treatment for oncological indications who are candidates for cardiac surgery.