My otherwise healthy 17 yo male kitty diagnosed with skin cancer - how

My sweet, sweet kitty, Nickee had what I thought was kitty acne on his chin, but it becomes crusty and grows like a stalactite and then drops off and then grows again. I took him to the vet and they got a sample of it and state it is cancer.....the gave him a shot of an antibiotic that lasts two weeks..can't think of the name of it....was that my first mistake?

I have CDS and DMSO at home....How do I proceed to cure him.....? or should i let them do the surgery to get as much off as they can?

Any experience would be useful.....I don't want to lose him....He's such a sweet guy. 17 years old and going strong....

I attached his pic...I hope you can see him.

Thank you in advance for all help