I Am On Megestrol Acetate 80 Mg. Twice A Day

I am on Megestrol Acetate 80 mg. twice a day as well as Ibrance 125 mg. for 3 weeks. I have been fighting breast cancer for 28 years. This is my 4th reoccurance in that time spanse. Some months my turmor markers are down to 6, but the last blood work said that it was now 12. Why does this keep happening? It always comes back on my left mastectomy side. Thank you for your response.
Email is YYYY@YYYY