Patient selection: malignant lymphoma, Hodgkin's or non-Hodgkin's disease
The response to therapy may be classified based on:
(1) PET-CT based response, also known as the metabolic response
(2) CT based response, also referred to as the radiologic response
The PET-CT scan would not be relevant if the lymphoma did not show FDG-avidity.
Criteria for PET-CT based nonresponse - all of the following:
(1) FDG uptake with score 4 or 5 on 5-PS at the end of treatment AND not significantly changed to that seen at baseline
(2) residual FDP uptake in bone marrow little changed compared to baseline
(3) no new lesions
where:
• FDG uptake before the end of treatment can be seen in responding tumor.
• Diffuse uptake in the bone marrow may reflect reactive change to chemotherapy.
Criteria for CT based nonresponse - all of the following:
(1) less than 50% decrease in the sum of the perpendicular products (SPD) in up to 6 measurable nodal and/or extranodal sites without evidence of disease progression
(2) smaller lesions (not measured for SPD) are not increased
(3) enlarged organs do not show further enlargement
(4) no new lesions
where:
• Assessment of bone marrow was designated not applicable to radiologic response.
