@earscan,- What a great question! I think that everyone who has had cancer asks something similar to this. I have had 2 different types of lung cancer, 10-years-apart. They were/are NSCLC.

Squamous cells are nasty cells that like to return. They form from the lining of the anal canal. They are the most common type of anal cancer. Anal cancer is fairly rare. Many people believe anal cancer is caused by the human papillomavirus (HPV).
https://www.mayoclinic.org/diseases-conditions/anal-cancer/symptoms-causes/syc-20354140
Squamous cell cancers usually spread to nearby lymph nodes and they can spread to nearby organs, as yours did. My two cancers were 10 years apart. I don't know why cancers wait and upend our lives like this. I sure wish I knew. If everything was removed and it returns then it would be, of course, to another part of your body, It can't possibly return to something that isn't there.

Cancer patients are always looking over their shoulders wondering if there will be a next one. And this is especially true for people with very virulent cancers. The best way to stay on top of this is to get regular testing, and any treatments, and live the best life that you can. Colleen has given you some wonderful sites to help with this fear. But it really is up to each of us to examine what is important to "us" in life and center on that. And that is pretty tough to do. There's no easy with cancer, no path to what is right or wrong, good or bad. You have to chose what is good for you, what feels comfortable and right for you and your family.

I know that this is much different than any other hard decisions that you have had to make, about how to cope with something tough. But it might be a starting point for you, right now, this minute. Make lists of what the pros and cons are to worrying about if or when you might have another cancer. That never got me anywhere so worrying only hurts me and makes my life miserable. A lot of times I can't escape it either. The thought is like a moccasin plant. It's a huge trap.

What have you done in the past to get through very hard times? I could use some help with this too!