3. Response to treatment.

Response	Primary tumour	Metastatic sites
Complete response	No tumour	No tumour; catecholamines normal
Very good partial response	Decreased by 90% to 99%	No tumour; catecholamines normal; residual 99Tc bone changes allowed
Partial response	Decreased by more than 50%	All measurable sites decreased by > 50%. Bones and bone marrow: number of positive bone sites decreased by > 50%; no more than 1 positive bone marrow site allowed
Minimal response	No new lesions; > 50% reduction of any measurable lesion (primary or metastases) with < 50% reduction in any other; < 25% increase in any existing lesion
No response	No new lesions; < 50% reduction but < 25% increase in any existing lesion
Progressive disease	Any new lesion; increase of any measurable lesion by > 25%; previous negative marrow positive for tumour

Reference: Brodeur 1993.