Objectives -

To achieve an overview of the past approaches and recent developments in the treatment of refractory or relapsed HB, HC or HON NOS in children
To investigate the short- and longterm outcomes in patients treated with these regimes in order to identify the most promising treatment approaches for the patient cohort
To collect data on initial presentation prior to relapses
To document patient and tumor characteristics at relapse and/or progression
To identify relapse/progression patterns, not with respect to prior treatments but rather to location/extent/timing (early vs late)
To document relapse/progression treatment
To document response to treatment and status at end of treatment
To document longterm outcome at last visit