Lymph node classification in E‑PSMA reporting guidelines for PSMA‑PET

We read with great interest the recently published “E-PSMA: the EANM standardized reporting guidelines v1.0 for PSMA-PET” by Ceci et al. [1] and applaud the authors for harmonising diagnostic interpretation criteria and developing a structured reporting system for PSMA-PET in prostate cancer. We have since implemented this reporting system into clinical practice at our tertiary hospital in Brisbane, Australia. However, we would like to highlight a small but important caveat in the application of the molecular imaging TNM (miTNM) reporting system regarding common iliac lymph node staging. Ceci et al. explain that the recommended miTNM classification was initially proposed in the PROMISE criteria [2] and provide a table summarising the miTNM classification. Specifically, regional lymph nodes are classified as miN0 (no positive regional lymph nodes) or miN1 (positive regional lymph nodes), whilst extra-pelvic lymph nodes are classified as miM1a. The E-PSMA article does not explicitly define what constitutes regional lymph node status and defers to the PROMISE paper. In summary, we strongly endorse the E-PSMA reporting guidelines but propose that common iliac nodal metastases are classified as miM1a disease (rather than miN1 disease as suggested by PROMISE) for consistency with established staging and PSMA-PET trial criteria by clinicians using the miTNM system.