Fifty-five percent complete remission of mammary carcinoma in mice with 5-fluorouracil and chloroquine.

Injection of 5-fluorouracil (5-FUra) [12 mg/kg i.p. (0.1 ml) every other day] and chloroquine phosphate (CP) [10 mg/kg i.p. (0.1 ml) daily] after the 19th day postimplant brought about a 55% complete remission of mammary carcinoma (C3HBA) in 2 separate experiments. FUra used alone brought about 40% complete tumor remissions, whereas CP used alone resulted in 30% complete remissions. None of these tumors reappeared before 189 days postimplant in Experiment 1 and 120 days postimplant in Experiment 2. The 5-FUra + CP treatment showed statistically (P less than 0.05) smaller tumor sizes compared to control mice tumor sizes on each of 13 check days after treatment was begun. The CP-treated tumors were statistically smaller than the control tumors on 10 check days, whereas the 5-FUra-treated tumors were smaller than the control tumors on 9 check days. The 5-FUra-treated tumors were statistically smaller than the CP-treated tumors on 2 check days (23 and 33). The 5-FUra + CP-treated tumors were statistically smaller than the CP-treated tumors on 3 check days (36, 43, and 47), and the 5-FUra + CP-treated tumors were statistically smaller than the 5-FUra-treated tumors on the last 4 check days (54, 57, 61, and 64).