So sorry to hear about your poor puss, the vet will advise you on what kind of tumour it is and what lies ahead for your deer puss, I had a dog with bone cancer and had him put to sleep as there were no other options, if it is localised and not spread then he may well have his leg amputated, just bare in mind that he may need chemo depending on what cancer it is, only you know how he is in him self, 10 is not old for a cat, waite till vets appointment and talk thoroughly with them, write down questions you want answered before you go, as your head is in a different place when there, good luck, x