Purpose: To determine the effective dose of consolidation radiation in Hodgkin's disease (HD) patients with large mediastinal adenopathy (LMA) treated with combined modality therapy (CMT).
Methods and materials: Eighty-three HD patients with LMA receiving CMT between 1983 and 1997 at Duke University and Yale University were identified. Patients underwent complete clinical staging. The staging breakdown was: IA, 4 patients; IB, 1 patient; IIA, 25 patients; IIB, 33 patients; IIIA, 3 patients; IIIB-6 patients; IVA, 2 patients; and IVB, 9 patients. All patients received induction chemotherapy (CT) as follows: MOPP/ABV(D), 31 patients; BCVPP, 15 patients; ABVD, 24 patients; MOPP, 3 patients; and other regimens, 10 patients. Following 6 cycles of CT, patients were restaged and classified as having either complete response (CR) or induction failure (IF). Post-CT gallium scans were obtained in 52 patients. Patients with residual radiographic abnormalities were classified as having CR if they were gallium-negative and clinically well otherwise. Following induction CT, 78 patients had a CR. There were 5 IFs. Consolidation irradiation was administered to all sites of initial involvement in patients who had achieved CR. RT dose varied. Patients were grouped into the following dose ranges: < or = 20 Gy, 12 patients; 20-25 Gy, 24 patients; 25-30 Gy, 30 patients; > or = 30 Gy, 12 patients.
Results: Overall survival and failure-free survival were both 76% at 10 years. Of the 78 CR patients, 15 failed. Patterns of failure were in-field alone, 8 patients; out of field alone, 2 patients; and combined, 5 patients. Failure patterns by RT dose were: < or = 20 Gy, 0/12; 20-25 Gy, 7/24; 25-30 Gy, 5/30; > or = 30 Gy, 3/11. There was no apparent correlation between RT dose and subsequent failure. Post chemotherapy gallium scans were helpful in predicting for failure. Of 48 patients in whom the gallium was negative after chemotherapy, there were 6 failures, compared with 9 failures among 30 patients in whom gallium was not done after chemotherapy (p = 0.066). Additionally, patients receiving adriamycin-based chemotherapy regimens had improved outcomes compared to those not receiving adriamycin (p = 0.03.)
Conclusions: These retrospective data suggest that low-dose radiotherapy following CR achieved with induction chemotherapy (particularly when documented with gallium scanning) may be as effective as higher doses for bulky HD at presentation. Phase III trials are necessary for confirmation of this hypothesis.