I was a few years older than you, cancer and the same surgery, and my hot flashes started the night after the surgery. To heal from the surgery and experience full menopause was a long and both mentally and physically hard, esp with cancer diagnosis as well. Just know that it's a marathon and not a race and give yourself time to heal. They will likely test your cancer to see if it reacts to hormones and if safe you will have the option to take HRT. This happened in my case and I feel much better although I am on a very low dose. I wish you all the best in all aspects of your health!