Tanning, either directly in the sun, or in artificial tanning salon booths, is not a good idea for anyone because it increases the risk of developing skin cancer. Tanning beds
are the most dangerous because the rays of UV light are even more concentrated. According to the National Cancer Institute, women who use tanning beds more than once a month have a 55 percent higher risk of developing malignant melanoma, the worst kind of skin cancer.
You don't say what type of cancer you've been treated for, but the fact that you've already had cancer puts you at risk of developing either a recurrence or another type of cancer.
If I were you, I'd stick to bottle or spray-on tans; they are safe and can look just as good.