Abstract

Background: Interim PET after two cycles (PET2) has historically guided risk-adapted therapy in Hodgkin lymphoma (HL). Its value with frontline brentuximab vedotin plus doxorubicin, vinblastine, and dacarbazine (BV + AVD) is uncertain, as BV + AVD improves progression-free survival and may reduce the prognostic relevance of early metabolic response. Our aim was to assess whether PET2 retains prognostic utility in HL patients treated with BV + AVD. Methods: We retrospectively reviewed 55 newly diagnosed classical HL patients treated with frontline BV + AVD. The primary endpoint was PET2 performance for predicting EOT PET positivity. Sensitivity, specificity, predictive values, and likelihood ratios were calculated with 95% confidence intervals. Results: Median age was 22 years (range 11–77), 49% were male, and 73% had stage III–IV disease. PET2 was negative in 51 patients (92.7%) and positive in 4 (7.3%). EOT PET was negative in 48 (87.3%) and positive in 7 (12.7%). Of seven EOT PET-positive patients, three were PET2-positive and four PET2-negative. Of 48 EOT PET-negative patients, 47 were PET2-negative and 1 PET2-positive. PET2 sensitivity was 42.9%, specificity 97.9%, positive predictive value 75.0%, and negative predictive value 92.2%. Positive likelihood ratio was 20.6; negative likelihood ratio was 0.58. Conclusions: In HL patients treated with BV + AVD, most achieve PET2 negativity, limiting interim PET discrimination. Negative PET2 adds little reassurance beyond the high baseline success rate, while positive PET2 is uncommon and identifies only a subset of eventual treatment failures. These findings question the routine use of PET2 to guide therapy in the BV + AVD era.

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