I know that your instinct is probably to "get the cancer out as soon as possible!" but you do have time to get a second opinion, and I definitely think you should do so. If you hear the same thing, you will probably feel more confident in the decision - and if you hear something different, your mom will have another option.
If at all possible, get an opinion from a certified colon/rectal surgeon. Those surgeons (rather than general surgeons) are really the most qualified to make decisions such as whether or not your mom's rectum can be saved. It's not that other surgeons can't do the surgery (and they may want to), but survival outcomes are statistically better when using a colon/rectal surgeon.
Also, be sure to ask the current surgeon (and any second opinion docs) how many of these kinds of surgeries s/he has done in his life, and how often s/he does them now. You want someone who has already done hundreds and does them on a regular basis now (at least several times a month, if not more often).
If you need to find a colon/rectal surgeon in your area, go to the American Society of Colon and Rectal Surgeons:
http://www.fascrs.org/displaycommon.cfm ... clenbr=104. You can look up all the ones in your state.
The good news is that if your mom's rectum does have to come out, she can have a colostomy and live a very full life with it! This was not always an option.
Hannah
Hannah K. Vogler
Co-Founder, The Colon Club
cousin of Amanda Sherwood Roberts
dx 1/99 Stage III at age 24
died January 1, 2002 at age 27