Influence of dietary fat intake on local recurrence and progression of metastases arising from MDA-MB-435 human breast cancer cells in nude mice after excision of the primary tumor.

This study was performed to evaluate the effect of dietary fat on the recurrence and metastasis of human breast cancer solid tumors growing in nude mice after surgical excision of the primary tumor. Female nude mice were fed either a high- (23% corn oil) or a low-fat (5% corn oil) diet, and 7 days later 1 x 10(6) MDA-MB-435 human breast cancer cells were injected into a thoracic mammary fat pad. Tumors at the injection site grew more rapidly in the animals fed the high-fat diet. Nineteen of 30 animals in each dietary group had tumors with a surface are > or = 1 cm2 within 10 weeks of injection, at which point the tumors were excised and the animals were followed for another eight weeks. Tumors recurred at the excision site in 8 of 19 animals fed the high-fat diet and in 9 of 19 animals fed the low-fat diet; however, the growth rate was more rapid in the group fed the high-fat diet. Lung metastases occurred with similar frequency in the two groups with local recurrences, but with a positive correlation between recurrent tumor weight (greater in the animals fed the high-fat diet) and the severity of lung metastatic involvement. In the mice without recurrence, 4 of 11 (36%) animals in the group fed the high-fat diet had macroscopic lung metastases compared with only one mouse, with minimal involvement, in the group fed the low-fat diet.