• Sarah A Milgrom, Wenli Dong, Mani Akhtari, Grace L Smith, Chelsea C Pinnix, Osama Mawlawi, Eric Rohren, Naveen Garg, Hubert Chuang, YehiaZeinab AbouZADepartment of Radiation Oncology, MD Anderson Cancer Center, Houston, Texas., Jay P Reddy, Jillian R Gunther, Joseph D Khoury, Tina Suki, Eleanor M Osborne, Yasuhiro Oki, Michelle Fanale, and Bouthaina S Dabaja.
• Department of Radiation Oncology, MD Anderson Cancer Center, Houston, Texas. Electronic address: samilgrom@mdanderson.org.
• Int. J. Radiat. Oncol. Biol. Phys. 2017 Feb 1; 97 (2): 333-338.

PurposeIn early-stage classical Hodgkin lymphoma, fluorodeoxyglucose positron emission tomography (PET)-computed tomography (CT) scans are performed routinely after chemotherapy, and the 5-point Deauville score is used to report the disease response. We hypothesized that other PET-CT parameters, considered in combination with Deauville score, would improve risk stratification.Methods And MaterialsPatients treated for stage I to II Hodgkin lymphoma from 2003 to 2013, who were aged ≥18 years and had analyzable PET-CT scans performed before and after chemotherapy, were eligible. The soft tissue volume (STV), maximum standardized uptake value, metabolic tumor volume, and total lesion glycolysis were recorded from the PET-CT scans before and after chemotherapy. Reductions were defined as 1 - (final PET-CT value)/(corresponding initial PET-CT value). The primary endpoint was freedom from progression (FFP).ResultsFor 202 patients treated with chemotherapy with or without radiation therapy, the 5-year FFP was 89% (95% confidence interval 85%-93%). All PET-CT parameters were strongly associated with the Deauville score (P<.001) and FFP (P<.0001) on univariate analysis. The Deauville score was highly predictive of FFP (C-index 0.89) but was less discriminating in the Deauville 1 to 4 subset (C-index 0.67). Therefore, we aimed to identify PET-CT parameters that would improve risk stratification for this subgroup (n=187). STV reduction was predictive of outcome (C-index 0.71) and was dichotomized with an optimal cutoff of 0.65 (65% reduction in STV). A model incorporating the Deauville score and STV reduction predicted FFP more accurately than either measurement alone in the Deauville 1 to 4 subset (C-index 0.83). The improvement in predictive accuracy of this composite measure compared with the Deauville score alone met statistical significance (P=.045).ConclusionsThe relative reduction in tumor size is an independent predictor of outcome. Combined with the Deauville score, it might improve risk stratification and contribute to response-adapted individualization of therapy.Copyright © 2016 Elsevier Inc. All rights reserved.

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