PRRT of neuroendocrine tumors: individualized dosimetry or fixed dose scheme?

Great efforts have been made in dosimetry for individualizing PRRT. However, many centers do not use dosimetry and its results hardly influence treatment. A reason for that is that reliable thresholds for organs-at-risk, kidneys and bone marrow, and treatment response are lacking. The nuclear medicine community must provide solid data from large trials delivering reliable thresholds, which then help to tailor PRRT according to organ doses (in order to reduce toxicity or increase treatment activity) or tumor doses (in order to increase activity to meet the response-threshold). Otherwise, development of radionuclide therapies will be done like big pharmaceutical companies do it currently: classical dose escalation studies and agreement on acceptable toxicity probabilities. Therapeutic radiopharmaceuticals will then be handled like other drugs, which on the other hand will increase availability of radionuclide therapies.