The effect of an antimetastatic agent plus intratumor chemotherapy was evaluated in mice bearing Lewis-lung carcinoma by measuring survival time and by histological examination. Polymeric flavan-3,4-diol (APF) from avocado seeds, Persea gratissima, administered alone directly into the tumor did not change survival time, although it partially destroyed the primary tumor. However, the drug administered in combination with an antimetastatic, 1,2-bis(3,5-dioxopiperazin-1-yl)ethane (ICRF-154), resulted in an increase in survival time. When 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) was used in place of polymeric flavanadiol as an intralesional drug, a significant increase in survival was also achieved. The effect of each drug alone and of their combination was evaluated by "responder analyses". Animals "cured" by the combination and rechallenged with 2 X 10(6) tumor cells showed that immunization could occur.