My wife is being treated for cancer. Our Catholic doctor said that pregnancy isn't an option during treatment, so she advised me to use condoms and recommended that my wife have her ovaries removed to prevent possibility of pregnancy. Is this good advice?

Your “Catholic” doctor has not given you sound moral advice. If you cannot accept any risk of pregnancy, then continence (marital abstinence) is your only option. No conditions—even such difficult conditions as you and your wife are facing—make it moral to use contraception or sterilization. During this difficult time it might be helpful to view this as a cross in your lives, an opportunity to take up your cross for Jesus (see Luke 9:23, 14:27). Spiritual direction can be helpful in this regard. For medical consultation from reputable Catholic doctors, I recommend visiting popepaulvi.org.