Hello sir, my father age is 66. He is suffering with prostate cancer. April 2017, he had done his surgery and after surgery his psa is 0.145. And November 2017 he had done his radiation therapy. Sep 2018, his psa level is 3.5 and within 2 months his psa level rises from 3.5 to 24. What is the reason? Is it possible too much variation. Doctor told him take another blood test in next month. He has not feel any symptoms.