Yes, the island told Ben, "YOU'RE MINE!" by giving him cancer. It was a way of reminding him that while the island can giveth (while you are working toward bettering the island) the island can also taketh away (while you are preoccupied with fertility and creepy Juliet stalking). I think the island brought the cancer to the ben. In my opinion.

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...embrace the senile genius...
watch him reinvent the wheel...