Risk- and response-adapted strategies for the management of Hodgkin lymphoma
Therapy for Hodgkin lymphoma (HL) is associated with excellent long-term survival rates, of 80% of more. Extended follow up has described late treatment-related toxicities, principally secondary malignancies, cardiovascular disease and infertility. Given the young age of many patients, there is a desire to offer a more personalised approach, correlated to individual tumour biology that enables treatment deescalation in low risk patients to reduce toxicity, and treatment intensification in high risk patients to reduce treatment failure. Contemporary therapeutic strategies have involved risk assessment based on staging and clinical factors. The use of functional imaging with 18F-fluorodeoxyglucose positron emission tomography (18F-FDG-PET) as a predictive tool to identify early non-responders has been well validated and outperforms the risk stratifying International Prognostic Score (IPS). HL has particularly high FDG-avidity (97-100%), with FDG-PET scanning reflecting metabolic activity and acting as a surrogate biomarker for chemosensitivity. International consensus on the methods of reporting and interpreting FDG-PET scans has enabled their use to be standardised and reproducible. Given that primary therapy fails for 15-20% of patients, the use of combined FDG-PET and computerised tomography (FDG-PET/CT) to provide a response-adapted strategy to guide management is under investigation in numerous prospective clinical trials. They aim to determine whether early response scanning can be used to directly modulate subsequent therapy, through intensifying or abbreviating chemotherapy regimens and/or omitting radiotherapy. Integrated multi-modality imaging and advanced conformal planning techniques have led to the emergence of radiotherapy strategies such as involved-node radiation (INRT) that aim to optimise treatment volumes and maintain efficacy whilst lowering toxicity. Study groups have incorporated these modalities in trial designs to assess whether a PET-directed, individualised approach can become the new standard of care.