The predictive value of positron emission tomography scanning performed after two courses of standard therapy on treatment outcome in advanced stage Hodgkin's disease.
We explored the predictive value on therapy outcome of an early evaluation of treatment response by 18F-fluorodeoxyglucose position emission tomography (18F-FDG-PET) scan performed after two courses of conventional standard-dose chemotherapy in advanced-stage Hodgkin's disease. One hundred and eight patients with newly-diagnosed Hodgkin's disease in stage IIA with adverse prognostic factors, or in stage IIB through IVB, were re-staged with FDG-PET after two cycles of ABVD (PET-2). The end-point of the study was the predictive value of PET-2 on 2-year progression-free survival and 2-year failure-free survival. No treatment variation based only on PET-2 results was allowed. Eighty-eight patients attained complete remission (CR) while 20 showed disease progression during therapy or within 6 months after having reached CR; one patient relapsed. PET-2 was positive in 20 patients: 17 progressed during therapy, one relapsed and two remained in CR. By contrast, 85/88 (97%) patients with a negative PET-2 remained in CR; three progressed or relapsed early after the end of the chemotherapy. Thus, the positive predictive value of a PET-2 was 90% and the negative predictive value was 97%. The sensitivity, specificity and overall accuracy of PET-2 were 86%, 98% and 95%, respectively. The 2-year probability of failure-free survival for PET-2 negative and for PET-2 positive patients was 96% and 6%, respectively (log rank test = 116.7, p < 0.01). 18F-FDG-PET scan performed after two courses of conventional standard-dose chemotherapy in advanced-stage Hodgkin's disease was able to predict treatment outcome in 103/108 (95%) of the patients.