Interim Positron Emission Tomography Scan Predicts Early Outcomes Of Patients With Peripheral T-Cell Lymphoma

Interim positron emission tomography (PET) scan has shown to be useful for evaluating response in Hodgkin lymphoma. And, there has been increasing interests in using interim PET for predicting outcomes in diffuse large B-cell lymphoma. However, few data are available regarding prognostic value of interim PET in patients with peripheral T cell lymphoma (PTCL). Recently, in an attempt to standardize reporting criteria for interim PET, Deauville five-point scale (5-PS), which visually assess the uptake of lesions in comparison with background mediastinal and liver uptakes, were proposed, but this was not investigated in PTCL. Therefore, the aim of this study was to determine the prognostic role of interim PET, assessed by Deauville 5-PS, in patients with PTCL treated with systemic chemotherapy.

We consecutively enrolled newly diagnosed PTCL patients, treated with systemic chemotherapy (CHOP/CHOP-like or non-anthracycline-based) and had the baseline PET data with ³1 evaluable hypermetabolic lesion between 2006 and 2012 in two Korean institutions. Patients treated with upfront chemoradiotherapy before interim PET scan were excluded. Interim PET scan was performed after 3 cycles of chemotherapy, before 1 week of the next cycle. Interim PET response was visually assessed by 5-PS and four point or higher was regarded as positive. All PET assessment was performed by 2 nuclear medicine specialists at each institution, and the discrepancy of assessment was resolved by the agreement through discussion.

A total of 35 patients was included in this analysis. The median age was 60 years (range, 31-79) and 26 (74%) were male. Histologic subtypes included were PTCL, not otherwise specified in 10 (29%), extranodal NK/T cell lymphoma in 8 (23%), angioimmunoblastic T cell lymphoma in 7 (20%), anaplastic large cell lymphoma, ALK negative in 4 (11%), and others in 6 (18%). 22 patients (63%) were presented as advanced stage disease and 9 (26%) had B symptoms. ECOG performance status was ≥ 2 in 7 (20%), serum LDH level was elevated in 16 (46%), and bone marrow was involved in 5 (14%). Thus, 14 patients (40%) were classified as high risk (≥ 2 factors) by the prognostic index for PTCL (PIT). 31 patients (89%) completed planned systemic chemotherapy ± involved-field radiotherapy and 25 (71%) achieved complete response by systemic chemotherapy. 10 patients (29%) underwent consolidative autologous stem cell transplantation (ASCT).

Using 5-PS, interim PET scan was visually scored as follows; 1 point in 10 patients (29%), 2 in 6 (17%), 3 in 8 (23%), 4 in 7 (20%), and 5 in 4 (11%). Among these, 11 patients (31%) had 4 point or above were considered positive for interim PET scan. With a median follow-up of 43.4 (range, 4.3-89.8) months, progression-free survival (PFS; median, 5.2 vs 38.0 months, respectively; P=0.001) and overall survival (median, 12.6 months vs not reached, respectively; P=0.004) was significantly worse in patients with positive interim PET than those with negative results. In multivariate analysis for PFS, high risk of PIT (HR, 3.67; 95% CI, 1.13-11.99) and positive interim PET (HR, 4.02; 95% CI, 1.32-12.23) were independently associated with faster disease progression, whereas consolidation with ASCT was independent prognostic factor for better PFS (HR, 0.23; 95% CI, 0.06-0.84).

Visual assessment of interim PET scan using Deauville 5-PS appears to predict early outcomes of patients with PTCL. Patients with positive interim PET shows highly predictive of extremely poor outcomes. Therefore, our findings suggest further studies regarding early stratification based on interim PET results as a response-adapted treatment strategies in patients with PTCL are needed to improve outcomes.

No relevant conflicts of interest to declare.