The disappearance of prognostic factors in Hodgkin's disease.

The purpose of this conceptual (and somewhat provocative) article is to analyse the reasons for the disappearance of prognostic factors in Hodgkin's disease (HD) and to explore the consequences for further research from a biometrical point of view. The very concept of prognostic factors is about to resolve in HD. Prognostic factors gradually loose their predictive power as treatment is successfully adapted to the disease burden. Freedom from treatment failure and overall survival curves of patients in early, intermediate and advanced stages of HD are superimposable with the best current treatment protocols of the German Hodgkin's Lymphoma Study Group. This disappearance of prognostic factors in HD necessitates a certain conceptual remodelling. It's time to think quantitatively and bivariately, and we need to (i) synthesise existing 'prognostic' factors into a quantitative measure of disease burden or severity; (ii) develop a quantitative measure of treatment strength and (iii) relate these two quantities in nomogram curves indicating how much treatment a patient with a given disease burden requires to have, say, a 85%, 90% and perhaps 95% expected chance of cure.