BresciaMEd

Introduction: Interim-PET (i-PET) has shown an high prognostic impact in the definition of ABVD efficacy in advanced stage Hodgkin Lymphoma (HL). Patients with positive i-PET had a worst prognosis in comparison with those with negative i-PET. These data were reproduced in real life clinical setting and in a large series of prospective PET oriented studies. From these studies was pointed out an intriguing issue regarding patients with i-PET negative but with a positive results at the end of therapy (PET6 positive). This group of patients represent without doubt the failure of functional imaging in selecting chemosensitive versus not chemosensitive patients. Aim: The aim of this analysis was to identify, in a prospective PET oriented study supported by FIL (HD0801), those PET6 positive patients defining the clinical characteristics in order to identify earlier patients with i-PET negative but with an high probability of negative evolution that means progression of the disease. Methods: HD0801 study was a multicenter prospective PET oriented study involving patients with advanced stage HL treated with ABVD. Patients performed PET at staging after two cycles of ABVD (i-PET) and at the end of therapy (PET6) to define response to therapy. Results: Between September 2008 and April 2013, 520 patients were enrolled and 512 performed i-PET. Four hundred and nine were i-PET negative and continued ABVD, 16 patients interrupted therapy before end of therapy, 3 of these due to disease progression; the remaining 393 patients performed, after 6 ABVD, final PET to define response to therapy (PET6). In 355 PET6 was negative and in 38 patients it was positive confirming a progression of the disease. In summary patients with progressive disease after negative i-PET were 41: 38 (PET6 positive) and 3 progressed between i-PET and PET6. None of the analyzed clinical characteristics were significantly different between 355 PET6 negative and 41 PET6 positive a part for LDH value at diagnosis either in univariate or in multivariate analysis: Odds Ratio (OR) 2.33 (1.15 to 4.7). The only factor predicting OS in the group of patients with i-PET negative was the positive results of PET6 with an OR 83.74 (12.75 to 557.64). The OS from PET6 at 24 and 36 months was 99% and 98% for PET6 negative patients and 91% and 78% for PET6 positive patients. Conclusions: Patients with negative i-PET but with a positive PET at the end of therapy had a very bad prognosis even in comparison with i-PET positive patients salvaged with intensification of therapy. From our study only LDH value at diagnosis was associated with a significant probability to have a positive PET6, none of the other clinical characteristics were associated with this result. Probably biological and pathological markers could be associated with i-PET to increase the predictive power but in particular to reduce the false negative i-PET. Keywords: Hodgkin lymphoma (HL); positron emission tomography (PET).