Hi
As someone who has had this problem and lived, I can pass on my experience. I was initially treated, as you, by the removal of the offending lump. A CT scan at the time did show I was clear, but I was given regular monthly checks. After 12 months a CT scan picked up a recurrence. I was also immediately put on a 3-month course of chemo. I, like you, had a good survival chance.
When I informed the CAA that I was going to be on chemo, they initially told me that I would not be able to fly for 12 months. After the chemo, I was again put on monthly checks. After 6 months (9 months after the start of the chemo), I was given an "As or With Co-pilot" restriction and allowed back to flying. As I was flying a multi-crew helicopter, this wasn't a problem for me. I had that restriction on my licence for three years. As I was still all-clear, the restriction was removed but the CAA required copies of the regular tests I had to have. This stopped this year (7 years after the chemo) and I have just renewed my Class 1 today.
I am not totally sure of the make-up of the drugs I had, other than I did have Cisplatin. This has a side affect of tinnitis. However, I appear to have passed all my hearing tests with flying colours since the chemo.
If you have a friendly AME, discuss the treatment with him, or ask to speak to a CAA doctor at Gatwick (I have found them very approachable). You could also make a post on the Medical & Health forum of Pprune as there are some experts on there.
BHPS