My fiancee, 31, has prostate cancer and we are trying to conceive. is this still likely? he hasn't undergone any kind of treatment at this point.

It depends: It depends if the disease has affected his sperm he will definitely need a semen analysis. Another thing to look at is frezing (banking) his sperm as the treatment may make him sterile.

Yes: Providing he has not had surgery or radiation prostate cancer un treated will not affect fertility.

Bank sperm now: That is young for a man to get prostate cancer and it makes me concerned that it needs to be treated soon due to its likely risky and aggressive nature. It may b less aggressive but it is a rare scenario due to his age. Therefore he should bank sperm get treatment as needed in the near future. Even without a prostate his sperm can be extracted down the road from his testicles.

Depends on tx: If only the prostate is treated and no chemotherapy or hormonal therapy is needed, his sperm should remain unaffected but he may not be able to ejaculate enough to impregnate naturally. A urologist can discuss other ways to get sperm now or in the future.

Prostate cancer: Although prostate cancer is quite unusual at 31 years of age, it can occur this young. If he has been diagnosed by a urologist by means of transrectal biopsies of the prostate, then he almost certainly was advised to have radical prostatectomy. This surgery would render him unable to impregnate by intercourse although assisted reproductive methods would be available to you.