Tumour burden predicts treatment resistance in patients with early unfavourable or advanced stage Hodgkin lymphoma treated with ABVD and radiotherapy.

The purpose of the work was to investigate the factors predicting early resistance to treatment in Hodgkin lymphoma. Many staging parameters, including relative tumour burden (rTB), were analysed in 246 patients with Hodgkin lymphoma in relation to early failure, that is, less than complete remission (i.e. partial response, null response or progression) or occurrence of early relapse, as clinical expressions of resistance to treatment. Patients with early unfavourable disease were 129 and were treated with four to six cycles of ABVD + involved field radiotherapy; 117 patients with advanced stage disease received six cycles of ABVD + optional irradiation to no more than two sites. The rTB was volumetrically measured through the evaluation of staging computed tomography for all the lesions except bone marrow involvement, which was quantified by calculation. The relationship with early resistance was analysed with logistic regressions. The rTB demonstrated to be the best predictor of early failure in both patient subsets, being superior to the multiparameter International Prognostic Score. The rTB showed a significant exponential relationship with the relative risk of early failure, and with inclusion of the extranodal involvement into the model, a single equation became adequate to predict resistance in both early unfavourable and advanced stage patients. The conclusions are that the rTB is the best pretreatment factor related to the risk of resistance to combined ABVD + radiotherapy and that this relationship can be mathematically expressed in an easy way. A simplified assessment of rTB is highly desirable.