Probably not. The ASRM is about to publish a position paper suggesting that cancer does not come from IVF. It is very difficult to "prove" these positions. We also find that most of the risk from fertility treatment comes from the reason we do IVF - infertility. Still, I would think twice about doing IVF when the results are very low (a philosophy for any treatment- do them only when benefits outweigh risk).
I don't believe it. I saw the studies, such as they are, and was unimpressed. Numbers, but no reason "why". Women who have their families late are at greater risk for breast and ovarian cancer anyway, as are those with some hormonal problems that may have caused the infertility. And studies of risk beg for other confounding variables. It's worth it if you wan to be a mother.