Consumers Union did a study on fish oil capsules and found essentially no contamination of Hg or anything else in brands from reputable manufacturers -- the mercury tends to stay with the fish tissue not the oil.

There is however evidence that flax oil (not flax-seed) enhances the growth of prostate cancer.

There are also several clinical studies which have shown positive impacts (reduction of PSA, reduction in recurrance etc.) for men with prostate cancer who are given lycopene. However this is prostate cancer, an adenocarcinoma, so it is probably pushing the envelope to transfer these results to oral SCCs. You are probably best off eating a Mediterranean-type diet with lots of olive oil, fruits, vegatables, low on red meat and dairy -- which has been linked to reduced risk of cancer, heart disease and other problems.

Gail