I get the idea that any "mucking about" with fertility for the purpose of preventing or ending pregnancy is forbidden. The example of an fallopian tube being removed to prevent hemorrhage (as opposed to directly end a pregnancy) has been given as something that is regrettable, but ultimately allowed (for lack of a better term).

My question concerns a rare, but not unknown situation. What if a woman develops some condition, say uterine cancer, that does not respond to more conservative treatments. The only viable medical option left is removal of some or all of the involved organs. How would this be viewed? Would it even be allowed, given the compulsory condition that she has already exhausted her known options?

Thanks.

edited for linguistic clarity

Following the principle of double effect it would be allowed.

For the nature of the act is good (removing a sick organ).
For the intent is good (intending the healing and the sterility tolerated).
For there is proportionate reason to do so (life of the mother)
For the good effect happens before the bad so that one does not do evil for the sake of good.

Put another way it is not formal cooperation with evi..