PRRT: Defining the paradigm shift to achieve standardization and individualization.

Peptide receptor radionuclide therapy is a treatment for inoperable or metastatic neuroendocrine tumors. A key issue is the need to standardize the treatment and develop randomized controlled trials. Standardization would help define the characteristics of response, including progression-free survival; provide homogeneous phase II and III studies; delineate the position of peptide receptor radionuclide therapy in the therapeutic algorithm for neuroendocrine tumors; and establish the basis for approval by the regulatory authorities. Standardization of treatments is the starting point to redefine the treatment paradigm from a one-size-fits-all to a personalized treatment. To delineate the treatment paradigm, treatments should be optimized for efficacy and minimization of long-term toxicity, through dosimetry, and adapted to each individual, including relevant patient characteristics. Although differences in therapy outcomes may be explained by the specific absorbed dose (or biologically effective dose), they may also be related to discrete tumor- and patient-specific features. In this respect, a particular area of investigation is the assessment of genetic elements regulating tumor cell proliferation, especially those involved in the response to cytotoxic therapies.