We need to understand the disease cancer itself .

Cancer is abnormal cells division in the body that inflicts consistent damage to it over time as we are aging
The type of cancer depends on which organ of the body it is attacking be it prostate, colon, ovary, throat etc

What is of primary concern is what can we do to checkmate or minimize the effect of free radicals in our body so as not to develop to full blown cancer?

VITAMINS AND OTHER SYNTHETIC SUPPLEMENTS

For any thing we consume, the more natural the better for the body.
For various tablets and vitamins available at our disposal , it healthy choice to avoid them except where absolutely necessary.
It is healthier for the body and even for absorption and less tasking for various organs (kidney, liver) to get this nutrients from natural source which are mainly from fruit , vegetables and in a few cases animal protein sources .
This is the best and cheapest source.

There are a few healthy vitamins and minerals that are rare and it that case the easiest way is from supplements . Take for example saw Palmeto plant for prostate health. Since it is very rare to find , taking the supplement is the best option. This just an exception.
Nature has provided must of the vitamins and minerals for our health needs , we just have to make use of them for our long term benefits.