Procarbazine

Confirmation, by a different route from HD18, that the interim scan can safely direct de-escalation in advanced Hodgkin lymphoma, and that most of the toxicity of escalated BEACOPP can be avoided in the 84 per cent of patients who respond early.

The interim scan should be used to intensify treatment in early Hodgkin lymphoma, not to withhold radiotherapy. The 99.0 per cent five-year progression-free survival in the scan-negative favourable group with combined-modality treatment is the number any radiotherapy-sparing strategy has to match.

The basis for four cycles of escalated BEACOPP as the German standard when the interim scan is negative, and the reason rituximab was abandoned as an addition to that regimen. The authors recommend the scan-guided strategy for all patients with advanced-stage disease.

Radiotherapy followed by PCV is the standard for high-risk grade 2 IDH-mutant glioma; whether temozolomide can replace PCV, and whether vorasidenib can defer both, are the current questions.

The reason every current Hodgkin lymphoma trial is a de-escalation trial, and the reason survivors need lifelong surveillance rather than discharge at five years. It is also a warning about assuming that a gentler protocol is a safer one until a cohort has been followed long enough to say.

Together with RTOG 9402, this trial made radiotherapy followed by PCV the standard for 1p/19q-codeleted anaplastic oligodendroglioma; the CODEL trial is now comparing PCV with temozolomide.