Hi Sam
Hopefully the numbness will go. Husband's wore off very quickly after each chemo cycle and is normal now ( husband = normal

).
Now, like Cancerdad, I would like to put forward my two-penny's worth. Chemo and radiotherapy are great tools for the medical profession to use in their fight against cancer. But they are not the only tools in the kit bag. Surgery is one of the best tools to cut out a cancerous growth, particularly if the chemo has done its work on shrinking the size down to a more operable level. Of course, you must be worried about the similarities to your mum but each patient is different and I am sure that if you tell your surgeon about your fears or concerns, he/she will do their utmost to reassure you. You will be warned of the risks of undertaking the operation but you should also be asking about the risks of not undertaking the operation.
Regarding the use of chemo as the next line of deffence as opposed to surgery. This may or may not be possible. Each time you have chemo your body gets used to it and eventually the chemo is of no use, for example husband could only have 12 cycles of oxaliplatin but after 6 cycles you could see from his charts that the effectiveness of reducing the tumor size was losing it's strength.
Some of the chemo drugs are good for reducing tumor size, some are good for stop the multiplication of cancer cells, some stop the blood supply to tumors. But there are limitations with all the drugs as to how effective they will be for your own particular case.
The chemo you have already endured seems like an aggressive treatment plan which is in place to treat an aggressive cancer. In my opinion you have to fight the cancer with everything you can and this includes surgery.
btw, in the UK where or if a colostomy is required, only 30% become permanent. My husband is a stage 4 rectal cancer survivor but did not need a colostomy. He had 2 surgeries and chemo and radiotherapy and is alive and kicking.
hope this helps but sorry it is a long ramble
ktee