The present invention in the field of cancer therapeutics is based on the finding (illustrated in Figure 4) that when cannabinoids are administered to cancer cells after a chemotherapeutic agent has been administered, the combined treatment leads to lower cancer cell viability than administration of the chemotherapeutic agent alone. There is provided a pharmaceutical composition comprising a chemotherapeutic agent for use in the treatment of breast cancer, wherein said treatment comprises a first phase in which the chemotherapeutic agent is administered, and a subsequent second phase in which a cannabinoid is administered.
