What is the optimal treatment volume in Hodgkin's disease patients undergoing high-dose chemotherapy and adjuvant radiation therapy?

To determine the optimal treatment volume in Hodgkin's disease patients undergoing high-dose chemotherapy (HDCT) and radiation therapy (RT), failure sites were reviewed in 56 patients. Twenty-one (38%) received involved-field RT (IFRT) before or after HDCT encompassing sites of prior disease. Failure sites were designated as previously involved (old) or uninvolved (new) sites. Seven patients (12%) died in the immediate post-HDCT period, leaving 49 evaluable (median follow-up, 41 months). Twenty-five patients (51%) relapsed (14 HDCT, 11 HDCT + IFRT): seven (28%) in old, eight (32%) in new, and ten (40%) in old and new sites. Six of the seven who relapsed in old sites received HDCT alone, whereas seven of the eight who relapsed in new sites received IFRT. Relapse in old sites was particularly common in patients failing to achieve a complete response. The most common new failure site was nodal, occurring in 11 patients and was primarily (10/11) adjacent to an old site. Although it controls prior disease, IFRT is insufficient in Hodgkin's disease patients undergoing HDCT. Relapse is common in new nodal sites and is primarily adjacent to prior sites. These results suggest that extended-field RT encompassing old and adjacent uninvolved nodal sites may be the optimal treatment volume in these patients.