Hello dear user of HCM! Thank you for sharing your concerns with us! The answer is no! There is no prostate cancer with normal PSA, and pain in the back or buttock in prostate cancers comes after the other typical signs, like urinary infections, pain while urination, difficulty to urinate, lose of weight, etc, If your husband has not these symptoms but just back/buttock pain the prostate cancer is not likely. There are so many causes that cause lower back pain such as, muscle straining due to physical activity or work, hernia, vertebral compression, sciatic syndrome, Urinary tract stones, pelvic infections etc. I would suggest you to do a complete check-up, and a CT-scan or MRI, to find out the cause of these complains. I hope you will be fine soon, and I wish you a good health! DR ERIOL.