wondering1, I have been thinking, without knowing. The research is powered in directions that don't answer the questions we have. From the research we understand that these two anabolics lessen in effect after 15 month in most patients in clinical trials. Theory from bone markers is that while PTH therapy increases bone building cells rapidly at onset of treatment, but the presence of those cells increases the number of cells that break bone down until at about 15 months the patient has diminished osteoanabolic effect. Since it appears to be true that bone markers predict the three month effect of increased mineralized bone. It would be sensible to test bone markers at the 13th and then the 15th month. When those markers indicate a slowing down of bone growth stop the injections. From my limited experience, three weeks off the injections drops the CTX more rapidly than the P1NP, which also drops. This is not presently an approved use of bone markers. To your point, I think that the pause before the second phase restarts the initial benefits resetting the process. Individual results indicates that the risks, not cancer, but hypercalcemia and hyperparathyroidism are not inherent in the medication, but is hidden in some few individual's genetics.
From the clinicals we know that when you stop taking Tymlos or Forteo, whatever caused a person's osteoporosis will resume causing that loss of bone. Current protocol is to take and antiresorptive, usually Reclast before taking yet another medication.
Because of financial incentives and separately the political climate, I don't think there will ever be clinical trials.