You definitely need a second opinion. If a endocrinologist is not easily available, I would make an appointment with another type of medical doctor and get their opinion. It sounds like you have lost confidence in your endocrinologist and it is important that one can trust and talk to whoever is managing your healthcare. I have had osteoporosis for many years and I see a doctor of internal medicine. I took oral medicine for over five years with little improvement in my numbers, and some disturbing side-effects. It has now been over five years since I made decision to stop taking osteoporosis drugs and I might add, I refuse tests to even check my numbers as I have no intention at this time of taking them again! I've felt much better the last five years since going off the meds. I eat a diet for good bone health, exercise, and watchful that I don't do activities that might compromise my bones. My bone health may or may not have improved, but I absolutely will not go back on meds again until there are "proven" better drugs on the market. I don't know how much pain or disability you have due to your osteoporosis, but if it isn't a huge problem, maybe stepping back from the osteoporosis meds for awhile and concentrating only on the treatment for your cancer would be something you could consider. Wishing you the very best, and also my prayers.