The effect of chemotherapy on occult metastases after surgical removal of a non-immunogenic mouse carcinoma.

A transplantable non-immunogenic murine carcinoma of spontaneous origin, WHT Carcinoma N-C (Hewitt), was used to assess the effectiveness of melphalan (Ml) and/or methotrexate (Mx) for treatment of occult metastatic disease following surgical excision of primary tumors. Early surgical excision alone cured 66% of mice; later excision gave no cures. Maximum sublethal doses of chemotherapy rarely cured mice of metastases but did extend their survival time by up to 66% as compared with mice subjected to excision only. The influence of excision and chemotherapy on the frequency of local recurrence or pulmonary metastasis is discussed. Extrapulmonary metastases were 2.5 times more frequent in long-term than in short-term survivors, independently of treatment.