Investigation of risk factors for ¹⁷⁷Lu-DOTATATE-induced thrombocytopenia in routine follow-up

Purpose. - The thrombocytopenia induced by the ¹⁷⁷Lu-DOTATATE is one of its frequent, adverse effects. Its persistence causing problems in the subsequent management of patients, especially when the disease progression occurs, predicting it is a major issue. Due to the lack of knowledge about this subject, we searched to determine the existence of predisposing factors concerning the platelet toxicity in the standard follow-up. Material and methods. - This monocentric retrospective study included 20 patients with gastroenteropancreatic neuroendocrine tumors. Various parameters were analyzed, including: the standard blood analysis, the osteomedullary invasion factor, the spleen's volume and the estimated activity in the bone marrow or the spleen 24 hours post-injection. Results. - Four patients had a persistent grade 2 thrombocytopenia, one year after the last treatment. A decrease in platelet count after the first treatment above 30% and an osteomedullary invasion factor above 30% were highlighted as risk factors odds-ratio = 1 (P = 0.0379) and odds-ratio = 1 (P = 0.003) respectively. The initial platelet count, splenic length and estimated activity in the spleen after 24 h were correlated with platelet nadir value r = 0.5459 (P = 0.0128); r = ± 0,8105 (P < 0,0001) and r = ± 0.467; (P < 0.0001) respectively. Conclusion. - This study has shown that the decrease of platelet's count after the first round of treatment and the scale of osteomedullary invasion are risk factors for thrombocytopenia and has brought to light that the spleen acts as a factor impacting the severity of this thrombocytopenia. (authors)