Cancer prevention
If you are concerned about preventing cancer - and it appears that you should be - my strong suggestion is to take the anti-cancer protocol I posted here and follow the advice about diet, lifestyle (though you could be a bit less strict with the diet), removal of toxins (especially amalgam fillings) and strress removal and then take all the general vitamin and mineral supplements recommended (or make sure you get them via your diet and, in the instance of Vitamin D3, from daily sunshine). They are all important - particularly Vitamin D3, iodin and the trace minerals.
The only "strong" cancer fighting and immune boosting supplement you should need is oleander - and you can take a much lesser amount for prevention that for actively fighting cancer - perhaps a single dose or less every other day should be plenty. What I do is once or twice a year, just in case, take a full cancer fighting dose two to three times daily for a month and then back off to a single dose every other day in between. A good cleanse and detox three or four times a year would also be a good idea.
You might also wish to take a look at my series of article on "How to Live a Long and Healthy Life" for good information on staying healthy and cancer free and living longer:
A Plan for Living a Long & Healthy Life - Pt 1
A Plan for Living a Long & Healthy Life - Pt 2
A Plan for Living a Long & Healthy Life - Pt 3
A Plan for Living a Long & Healthy Life - Pt 4
DQ