PRRT side-effects prediction is a crucial point in the management of GEPNET.
GEPNETs patients treated in our centre with PRRT (177Lu-Oxodotreotide, 4 administrations,7.4 GBq) from 04-2019 to 12-2020 were considered. Haematopoietic, liver and renal toxicities were collected during PRRT and graded according to CTCAE v5. The population was subdivided as midgut/foregut, G1/G2 (see WHO 2019) and categorical grouped according to ECOG, number of metastatic sites, previous treatment lines (1 or ≥2) and therapies received before PRRT (splenectomy, Everolimus, alkylating chemotherapy). To test independence between CTCAE and patient characteristics Pearson and Wallis test were assessed. Logistic regression with Firth correction and bootstrap were performed to determine predictability of CTCAE onset.
67 patients (31(46.3%) males, mean age 63) were considered. Thirty-eight (56.7%) were midgut, 29 (43.3%) foregut, 24 (35.8%) G1 and 43 (64.2%) G2. Chemotherapy and Everolimus were the previous treatments in 13 (19.4%) patients, in both cases. Patients were treated with PRRT as 3rd or further lines in 34.3% (23) of the whole population and 48.3% (14) of foregut. All the patients showed at least one G1-G2 CTCAE, in particular anaemia (46,68.6%), thrombocytopaenia (32, 47.8%) and leukopaenia (30, 44.8%). G3-G4 were rare events, reported in 5(7.5%) cases considering haematological alterations (2 neutropaenia, 1 anaemia, 2 thrombocytopaenia) and 2 (3%) cases for liver (1 ALT, 1 INR alteration). Anaemia and thrombocytopaenia occurred in the same patient, causing discontinuation; all the other G3-G4 were transitional. No G3-G4 renal CTCAE were reported. Logistic regression showed that line of PRRT administration was the most powerful predictor of thrombocytopaenia (log Odds Ratio:1.54, CI 0.24 -3.03, p:0.019), anaemia (logOR 5.63, CI 1.19-12.84, p:0.004) and GGT alteration (logOR 1.88, CI 0.29-3.53, p: 0.02). Primary tumour histology (midgut versus foregut) was a good predictor of ALT (logOR 1.24, CI 0.045 -2.48, p: 0.04) and GGT alteration (logOR 1.3, CI -0.02-2.87, p: 0.05).
Line of PRRT administration is a strong predictor of CTCAE onset during PRRT. The results, if confirmed in larger cohorts, can have a huge impact on PRRT decision-making.
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