Patients who experience a relapse after initial wide-field, high-dose radiation therapy have a good prognosis. Combination chemotherapy results in 10-year disease-free survival (DFS) and overall survival (OS) rates of 57% to 81% and 57% to 89%, respectively.[1,2,3,4] For patients who experience a relapse after initial combination chemotherapy, prognosis is determined more by the duration of the first remission than by the specific induction or salvage combination chemotherapy regimen. Patients whose initial remission after chemotherapy was longer than 1 year (late relapse) have long-term survival with salvage chemotherapy of 22% to 71%.[4,5,6,7,8,9] Patients whose initial remission after chemotherapy was shorter than 1 year (early relapse) do much worse and have long-term survival of 11% to 46%.[4,8,10]
Patients who relapse after initial combination chemotherapy usually undergo reinduction with the same or another chemotherapy regimen followed by high-dose chemotherapy and autologous bone marrow or peripheral stem cell or allogeneic bone marrow rescue.[11,12,13,14] This therapy has resulted in a 3- to 4-year DFS rate of 27% to 48%. Patients who are responsive to reinduction chemotherapy may have a better prognosis. Two randomized trials have compared aggressive conventional chemotherapy versus high-dose chemotherapy with autologous hematopoietic stem cell transplantation for relapsed chemosensitive Hodgkin lymphoma (HL). Both trials show improvement in freedom from treatment failure at 3 years for the transplantation arm (75% vs. 45% and 55% vs. 34%, respectively); but no difference was observed in OS.[15,16][Level of evidence: 1iiDii] In two retrospective reviews of patients who underwent autologous bone marrow transplantation (ABMT) for relapsed or refractory disease, a comparison was made of those who received involved-field radiation therapy (IF-XRT) for residual masses after high-dose therapy versus no further treatment.[17,18] Those who received IF-XRT had improved progression-free survival. The use of human leukocyte antigen-matched sibling marrow (allogeneic transplantation) results in a lower relapse rate, but the benefit may be offset by increased toxic effects.[13,19,20] Reduced-intensity conditioning for allogeneic stem cell transplantation is also under clinical evaluation.[21,22,23,24,25] For patients with recurrent disease after ABMT, weekly vinblastine therapy has provided palliation with minimal toxic effects.[Level of evidence: 3iiiDiv]
The PDQ editorial boards use a ranking system of levels of evidence to help the reader judge the strength of evidence linked to the reported results of a therapeutic strategy. For any given therapy, results of prevention and treatment studies can be ranked on each of the following two scales:
Strength of the study design.
Strength of the endpoints.
Together, the two rankings provide a measure of the overall level of evidence. Screening studies are ranked on strength of study design alone...