The effectiveness of dietary n-3 plant and marine fatty acids and n-6 gamma-linolenic acid (GLA) was tested as an antimetastatic modality in the experimental model of metastasis of 13762MAT:B mammary adenocarcinoma cells.

Weanling female Fischer 344 rats were placed on one of the following diets: 1-23.52% blackcurrant oil (BCO), II-23.52% corn oil (CO), III-15.52% BCO + 8% fish oil (FO), IV-20.52% FO + 3% CO, and V-5% CO.

After 8 weeks, 15 rats per group were injected i.v. with 10(5) cells and diets were continued until sacrifice. In the 23.52% CO group (II), the number of small (< 2 mm) and large (> 2 mm) lung metastatic foci and their total volume were significantly greater than the BCO- and/or FO-fed groups (I, II and IV). Although the number of small metastatic foci was comparable in the 5% and 23.52% CO groups, the number of large foci and the total tumor volume were reduced in the 5% CO group.

These results suggest that, compared to a low-corn oil diet or a high-fat diet containing a mixture of marine and plant n-3 fatty acids plus n-6 GLA, a 23.52% corn oil diet can enhance experimental metastasis of mammary adenocarcinoma cells.

Total number of metastatic foci and tumor volume were the smallest in group III, receiving a combination of plant and marine n-3 fatty acids.