Metabolic Tumor Volume Is an Independent Prognosis Factor Predicting patient's Outcome in Hodgkin Lymphoma
Authors: Kanoun Salim , Rossi Cedric , Berriolo-Riedinger Alina , Humbert Olivier , Dygay-Cochet Inna , Chretien Marie-Lorraine , Legouge Caroline , Berthet Louis , Bastie Jean-Noel , Casasnovas Rene-Olivier 
Published: October 2019

Abstract
Abstract 3631
Positron emission tomography with [18F]fluorodeoxyglucose (PET) performed after two cycles of chemotherapy allows to predict treatment outcome in Hodgkin lymphoma (HL) with a pretty good accuracy specifically when the SUVmax reduction (DSUVmax) of the most hypermetabolic lesion is used to interpret interim PET. However, about 15% of false negative and 30% of false positive interim PET results are observed. To investigate the prognosis impact of the metabolic tumor volume at baseline (MTV0) we compared the respective clinical usefulness and prognosis value of the MTV0 and the SUVmax reduction between baseline PET (PET0) and interim PET (PET2) performed after 2 cycles of chemotherapy (DSUVmaxPET0–2) in a retrospective single centre study.
From January 2007 to January 2010, 59 consecutive patients with a first diagnosis of HL were treated in our institution. All patients received 4 to 8 cycles of chemotherapy including ABVD in 50 cases (85%) and BEACOPP in 9 cases. Radiotherapy was performed in 14 responding patients with localized disease. PET was done at baseline (PET0) and after 2cycles of chemotherapy (PET2) and therapeutic strategy was not modified according to PET2 result. All PET scans were reviewed by SK, ABR and IDC. MTV0 was measured with a semi-automatic method using various volume shapes and systematic 41% SUVmax thresholding. Based on a receiver operating characteristics approach patients with a MTV0 >225 cc were considered to have a hypermetabolic bulky disease. Interim PET were interpreted using DSUVmaxPET0–2 and patients with a DSUVmaxPET0–2 >71% were considered as good responders after 2 cycles. Progression-free survival (PFS) and freedom from treatment failure (FFTF) were analyzed according to MTV0 and DSUVmaxPET0–2.Median follow-up was 39 months (range: 6–62).
Median MTV0 was 120 cc (range: 10 – 1610) and 17 patients (29%) had a MTV0 >225 cc. Patients with a MTV0 >225 cc had more frequently a bulky tumor>10 cm (41% vs 5%; p = 0.0021). MTV0 (≤ 225 vs > 225) was predictive of 3-year PFS (85% vs 42%; p = 0.001) and FFTF (88% vs 45%; p = 0.0015). Bulky tumor was also predictive of 3-year PFS (44% vs 78%, p <0.04), but of border line significance for 3-year FFTF (80% vs 53%, p = 0.09). In multivariate analysis, using the international prognosis score, DSUVmaxPET0–2, MTV0 and bulky tumor as covariates, only DSUVmaxPET0–2 and MTV0 remained independent predictors for PFS (p= 0.0005; RR=6.4, and p<0.007; RR= 4.2, for DSUVmaxPET0–2 and MTV0 respectively) and FFTF (p= 0.0002; RR= 8.2,and p= 0.01; RR= 4.4, for DSUVmaxPET0–2 and MTV0 respectively). Then, 3 prognosis groups could be identified (Figure 1): patients with either DSUVmaxPET0–2>71 and MTV0≤225 (n = 37; 63%), or DSUVmaxPET0–2<71 or MTV0>225 (n = 17; 29%), or DSUVmaxPET0–2<71 and MTV0>225 (n = 5; 8%), had a 92%, 48%, and 20% 3-year PFS (p<0.0001) and a 94%, 54% and 20% 3-year FFTF (p<0.0001) respectively.
MTV0 is more relevant that tumor bulk to predict outcome of patients with Hodgkin lymphoma, and adds significant prognosis insights to interim PET response assessment. The combination of MTV0 with DSUVmaxPET0–2 allows identifying 3 subsets of HL patients with significantly different outcomes that may help clinicians to guide therapeutic strategy.
Figure 1: PFS according to DSUVmaxPET0–2 and MTV0 results Figure 1:. PFS according to DSUVmaxPET0–2 and MTV0 results
Solid line: patients with DSUVmaxPET0–2 >71 and MTV0 ≤225. Dashed line: patients with DSUVmaxPET0–2 <71 or MTV0 >225. Dotted line: patients with DSUVmaxPET0–2 <71 and MTV0 >225.

Disclosures:
No relevant conflicts of interest to declare.