The present invention relates to method and means for treating a vascularized solid tumor using a number of, in vitro prepared, anticellular agent(s)-carrying blood platelets to induce a thrombus formation within the tumor vasculature, and at the same time to deliver a high concentration of an anticellular agent within the tumor. The blood platelets are targeted and attached to the tumor vasculature using in vivo assembled binding complexes, each having at least one binding site specifically binding to tumor cells or to tumor-associated vasculature, and at least one binding site specifically binding to a blood platelet surface. The platelet-mediated thrombus formed within the tumor vasculature leads to occlusion of the tumor vasculature, with ultimate destruction of the centrally located tumor cells. This is followed by destruction or suppressing the growth or cell division of the peripherally located tumor cells, by the anticellular agent(s) carried by the blood platelets.