Twelve-Year Follow-up After Peptide Receptor Radionuclide Therapy

Peptide receptor radionuclide therapy (PRRT) has been used for more than 20 y as a systemic treatment approach in inoperable or metastatic somatostatin receptor-positive tumors. The purpose of this study was to analyze the long-term outcome of PRRT with regard to the most commonly used radiopharmaceuticals, ⁹⁰Y-DOTATOC and ¹⁷⁷Lu-DOTATATE. Methods: This retrospective clinical study included a total of 44 consecutive patients (27 men) with advanced tumors and enhanced somatostatin receptor expression. Mean age at initial diagnosis was 60 y (SD, 11.3 y; range, 40-84 y). Median follow-up was 80 mo. For ¹⁷⁷Lu-PRRT, the mean number of cycles administered was 5.3 ± 2.5 and the mean activity was 27.2 ± 14.9 GBq per patient. For ⁹⁰Y-PRRT, the mean number of cycles administered was 5.5 ± 2.6 and the mean activity was 14.7 ± 7.3 GBq per patient. Overall, 378 cycles were administered (mean, 8.6 ± 3.4 cycles per patient), with an overall cumulative activity of 1,514.1 GBq. Results: Median overall survival was 79 mo. Twenty-one (77.8%) of the 27 men and 9 (52.9%) of the 17 women had died 12 y after commencement of PRRT. The shortest duration of illness was 8 mo and the longest 155 mo. Severe side effects (World Health Organization grades III and IV) were seen in 9 of the 14 patients still alive. Chronic kidney disease in combination with anemia was the most common finding in the 9 patients with severe side effects. A poor prognosis was found for those patients who showed progressive disease, in comparison with patients with cumulative disease control after initial PRRT (log rank, P < 0.001), whereas women and patients with no more than 2 tumor sites seemed to especially benefit from PRRT (not reaching significance levels). Conclusion: PRRT is encouraging in terms of long-term outcome. Thirty-two percent (14/44 patients) of the patients with metastatic or inoperable disease were still alive more than 12 y after the beginning of radionuclide therapy. Possible predictors for favorable outcome are having an initial response to PRRT, having a low number of affected sites, and being female.