The presence of tumor nodules in organs often results in serious clinical manifestations and the permeation by cancer cells of sheaths surrounding organs often produces clinical manifestations of pleural effusion, ascites or cerebral edema. The present invention addresses this problem by providing a method for treating tumors comprising (a) intratumoral administration of a superantigen and/or (b) intrathecal or intracavitary administration of a superantigen directly into the sheath. Intratumoral superantigen results in significant and sustained reduction of the tumor size. Intrathecal administration produces significant sustained reduction of the fluid accumulation associated with clinical improvement and prolonged survival. Useful superantigen compositions for intrathecal and intratumoral injection include tumoricidally effective homologues, fragments and fusion proteins of native superantigens. Also disclosed is combined therapy that includes intratumoral or intrathecal superantigen compositions in combination with (i) intratumoral low, non-toxic doses of one or more chemotherapeutic drugs or (ii) systemic chemotherapy at reduced and non-toxic doses of chemotherapeutic drugs.La présence de nodules tumoraux dans des organes se traduit souvent par des manifestations cliniques graves, et la perméation de cellules cancéreuses au travers de gaines entourant des organes se traduit souvent par des manifestations cliniques dépanchement pleural, dascite ou doedème cérébral. Linvention vise à traiter ces manifestations à laide dun procédé de traitement de tumeurs comportant (a) ladministration intratumorale dun superantigène et/ou (b) ladministration intrathécale ou intracavitaire dun superantigène, directement dans la gaine. Les superantigènes intratumoraux permettent de réduire de façon importante et durable la taille de la tumeur. Ladministration intrathécale permet de réduire de façon importante et durable la quantité de liquide accumulée, ainsi que dobtenir une amélior
