Successful palliation in patients with advanced cancer with the many available antitumor agents has been a useful but fleeting reward in a number of patients with metastatic solid cancers. Many excellent reports1-7 are available on the response of various tumors to a number of these antitumor agents. Little correlation has been attempted in the many tumor areas available for cancer chemotherapy relating response to antitumor therapy with the many tumor variables. This paper is an attempt to present parameters of predictability of response for selecting patients for cancer chemotherapy. The correlation of response to therapy with the various tumor areas studied (breast, colon, and lung cancers) will include an evaluation of the response of the various tumor areas to a number of antitumor agents or combinations of agents which have had fairly extensive prior usage and evaluation. The principle variables to be evaluated will include (1) the agents utilized,