Cancer is an entirely new reality and set of life circumstances. There's absolutely nothing that says you have to keep being the same person that you always were. Thriving after cancer means growth, change, and evolution. You have the right to grow as a person in order to overcome what you're facing in life, and you don't need to apologize to anybody for doing so.
I'm fast approaching five years cancer free, and I've continued to grow and evolve so much even in the past year. It's not cancer that's forced me to evolve so much, but the demons it left inside of me that did. I'm a completely different, and far better person today than I've ever been.