Hematological neoplasias are the fourth cause of death in the world. All of them are responsible of bad quality of life, due to heavy therapies administration and a lot of side effects correlated to. It arises a new concept of "multitherapy", in which fatty acids availment is used to contrast and reduce toxic effects and ameliorate chemotherapeutic agents asset. In Vitro studies have confirmed that fatty acids, in particular ω-3 eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are able to help canonical therapies to contrast cancer cell expansion and proliferation. In clinical trials it is also almost clear that fatty acids are useful to build new personalized therapies for a better condition of life. In this review we have summarized most recent studies on cancer cell lines and clinical trials on patients with fatty acids supplementation in diet therapies. We have found that fatty acids could be useful to contrast side effects during chemotherapeutic drugs therapies; they are also able to block cancer cell metabolic pathways for proliferation and contrast adverse effects, even when they are used in combination with traditional therapies or innovative, like monoclonal antibodies or CAR-T therapy. These aspects are crucial for better health condition of patients.