Neurokinin-1 receptor (NK-1R) antagonists exert an antitumor action, are safe and do not cause serious side-effects. These antagonists (via the NK-1R) exerted multiple actions against cancer: antiproliferative and anti-Warburg effects, apoptosis, anti-angiogenic and antimetastatic. These multiple effects have been shown in a broad-spectrum of cancers. The drug aprepitant (an NK-1R antagonist) is currently used in clinical practice as antiemetic. In in vivo and in vitro studies, aprepitant also showed the aforementioned multiple antitumor actions against many types of cancer. A successful combination therapy (aprepitant and radiotherapy) has recently been reported in a patient suffering from lung carcinoma: the tumor mass disappeared and side-effects were not observed. Aprepitant could be considered as an intelligent bullet against cancer. The administration of aprepitant in cancer patients to prevent recurrence and metastasis after surgical procedures, thrombosis and thromboembolism is discussed as well as the possible link, through the SP/NK-1R system, between cancer and depression. Our main aim is to review the multiple antitumor actions exerted by aprepitant and the use of this drug is suggested in cancer patients. Altogether, the data support the reprofiling of aprepitant for a new therapeutic use as an antitumor agent.