In order to evaluate if patients with stage III-IV MCM are eligible for curative treatment PET/CT is performed. Since the diagnostic value of PET/CT is not unambiguously, a retrospective cohort study is performed to tailor optimal indication of PET/CT in patients with stage III MCM. A retrospective cohort study was conducted of all patients with stage III disease in a large oncologic teaching hospital in which PET/CT was performed from 2012 to 2016. The primary tumor- and regional lymph node characteristics were assessed to predict distant metastasis seen on PET/CT. A total of 73 patients were included of which 18% were restaged as stage IV by PET/CT. Twenty percent of the patients with a positive lymph node and 14% of patients with in transit metastasis or satellite lesions were restaged to stage IV. T-classification, ulceration and N-classification did not predict distant metastasis. Localization of the primary tumor significantly differed (P = 0.004). Localization on the head/neck resulted in a 32 greater odds of distant metastasis (P = 0.008). After a median follow-up of 36 months, 13 out of 60 (27%) stage III MCM patients were restaged as stage IV after the first performed PET/CT. This retrospective cohort study resulted in restaging of 18% of the stage III MCM patients by PET/CT, with therapeutic consequences. Patients with stage III MCM on the head/neck seem to have more distant spreading of the tumor than other localizations. Further investigation is needed, with larger sample sizes, to guide optimal indication of PET/CT.
Keywords: Malignant cutaneous melanoma; PET/CT; retrospective cohort; stage III.