BACKGROUND: The association between skeletal muscle and adipose tissue (body composition) and early response using positron emission tomography (PET) in pediatric Hodgkin lymphoma (HL) remains unstudied.

METHODS: Patients enrolled on Children's Oncology Group studies AHOD0031 (intermediate-risk HL) and AHOD0831 (high-risk HL) with digital abdominal computed tomography (CT) scans at diagnosis and PET scans after 2 cycles (PET2) were included. Two consecutive slices at the third lumbar vertebra were identified and skeletal muscle index (SMI, in cm2/m2) and total adipose tissue index (TATI, in cm2/m2) were calculated using sliceOmatic (Magog, Canada) and height at diagnosis. SMI and TATI were divided into quintiles (Q1 [lowest] to Q5 [highest]). Body mass index (BMI) was calculated using height and weight at diagnosis. The association between baseline body composition (SMI, TATI, BMI) and positive PET2 was examined using logistic regression, adjusting for age at diagnosis, sex, race/ethnicity, stage, histology, bulk disease and 'B' symptoms.

RESULTS: Among 1,033 included patients, PET2 was positive in 314 (30.4%). SMI was not associated with positive PET2. Extremes of TATI were associated with positive PET2, when compared with the middle TATI quintile (reference: Q3; odds ratio [ORQ1]=1.63, 95% confidence interval [CI]=1.03-2.60, P=0.04; ORQ2=1.82, 95%CI=1.17-2.82, P=0.008; ORQ5=1.94, 95%CI=1.23-3.05, P=0.005). The association between BMI in obesity range and positive PET2 trended towards significance (OR=1.42, 95%CI=0.98-2.04, P=0.06; ref=normal weight).

CONCLUSIONS: Extremes of adipose tissue at diagnosis influences early response among pediatric HL.

IMPACT: Validation of results from this study could inform studies investigating body composition-based chemotherapy dosing.