Absolute monocyte count at diagnosis could improve the prognostic role of early FDG-PET in classical Hodgkin lymphoma patients

Recently published international guidelines suggested that positron emission tomography (PET)-computed tomography (CT) could be utilized for response assessment using the Deauville criteria in fluorodeoxyglucose (FDG)-avid lym- phomas (Meignan et al, 2012). Interim PET (I-PET) scan- ning seems highly predictive of treatment failure in Hodgkin Lymphoma (HL) patients. We recently showed that the absolute monocyte count (AMC) has prognostic value in patients with classical HL (cHL) (Tadmor et al, 2015). Here, we show that the com- bined use of I-PET and AMC at diagnosis enables a more accurate projection of patient outcome in cHL. The present study is an ancillary branch of the analysis reported by Tadmor et al, (2015). Patients with histopatho- logical diagnosis of cHL previously enrolled in the Gruppo Italiano Studio Linfomi trials were eligible if data on all clini- cal and laboratory features and treatments, reported I-PET results, treatment response and follow-up were available. Response was defined according to the revised International Working Group guidelines (Cheson et al, 1999). An absolute lymphocyte count <06 9 10 9 /l and AMC > 075 9 10 9 /l were used as cut-off points. I-PET was performed after 2 cycles of treatment. A positive or negative I-PET was defined by the local investigators’ interpretation of the nuclear physi- cian’s scan report, which was based on a visual qualitative assessment. The principal end-point of the study was the impact of I-PET and AMC on progression-free survival (PFS); their impact on overall survival (OS) was the secondary end-point. Survival functions were estimated using the Kaplan–Meier method. Statistical comparisons between curves were per- formed with log-rank test, and the effect of the covariate was reported as hazard ratios (HR), from Cox regression. All patients had a diagnosis of cHL; 76% of cases had the nodular sclerosis (NS) subtype. Seventy-six patients (64%) were treated with classical ABVD (doxorubicin, bleomycin, vincristine, dacarbazine), and 23 (19%) and 19 (16%) with the more intensive BEACOPP (bleomycin, etoposide, doxoru- bicin, cyclophosphamide, vincristine, procarbazine, pred- nisone) and COPPEBVCAD (cyclophosphamide, lomustine, vindesine, melphalan, prednisone, epidoxirubicin, vincristine, procarbazine, vinblastine, bleomycin) regimens (Federico et al, 2009), respectively. Of the entire cohort, 104 patients (88%) achieved complete remission. Twenty-six patients had a positive I-PET (22%) and 28 (24%) had AMC > 075 9 10 9 /l at diagnosis. The median follow-up of the entire cohort was 88 months (range 5–142 months). The estimated 5-year OS was 91% (95% confidence interval [CI]: 84–95%). The 5-year PFS was 80% (95% CI: 71–86%). Patients with positive I-PET showed a worse PFS compared to patients with negative I-PET (51% and 88%, respectively; HR 587 [95% CI: 256–135]). Patients with AMC > 075 9 10 9 /l at diagnosis had a worse PFS compared to patients with AMC ≤ 075 9 10 9 /l (58% and 87%, respectively; HR 373 [95% CI: 161–864]). Multi- ple Cox proportional hazards (PH) regression, adjusted for International Prognostic Score 3–7, confirmed the prognostic role of I-PET (HR 532 [95% CI: 230–123]; P < 0001) and AMC >075 9 10 9 /l (HR 319 [95% CI: 132–768]; P = 0010). Figure 1A, B shows the PFS for I-PET and AMC, and Table I shows the uni- and multivariate Cox PH regres- sion for PFS. The prognostic role of I-PET and AMC on OS was also confirmed. Given the strong predictive value of both I-PET and AMC, we stratified patients by positive or negative I-PET and AMC > 075 9 10 9 /l or