Radiation dose selection in Hodgkin's disease patients with large mediastinal adenopathy treated with combined modality therapy

Purpose: To determine the effective dose of consolidation radiation in Hodg kin'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 betw een 1983 and 1997 at Duke University and Yale University mere identified. P atients underwent complete clinical staging. The staging breakdown was: IA, 4 patients; IB, 1 patient; IIA, 25 patients; IIB, 33 patients; IIIA, 3 pat ients; 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 classif ied as having either complete response (CR) or induction failure (IF). Post -CT gallium scans mere obtained in 52 patients. Patients with residual radi ographic abnormalities were classified as having CR if they were gallium-ne gative and clinically well otherwise. Following induction CT, 78 patients h ad a CR, There were 5 Ifs. Consolidation irradiation was administered to al l sites of initial involvement in patients who had achieved CR, RT dose var ied. Patients were grouped into the following dose ranges: less than or equ al to 20 Gy, 12 patients; 20-25 Gy, 24 patients; 25-30 Gy, 30 patients; gre ater than or equal to 30 Gy, 12 patients. Results: Overall survival and failure-free survival were both 76% at 10 Sea rs. Of the 78 CR patients, 15 failed. Patterns of failure were in-field alo ne, 8 patients; out of field alone, 2 patients; and combined, 5 patients. F ailure patterns by RT dose were: less than or equal to 20 Cy, 0/12; 20-25 G y, 7/24; 25-30 GS, 5/30; greater than or equal to 30 Gy, 3/11, There was no apparent correlation between RT dose and subsequent failure. Post chemothe rapy gallium scans were helpful in predicting for failure. Of 48 patients i n whom the gallium was negative after chemotherapy, there were 6 failures, compared with 9 failures among 30 patients in whom gallium was not done aft er chemotherapy (p = 0.066). Additionally, patients receiving adriamycin-ba sed chemotherapy regimens had improved outcomes compared to those not recei ving adriamycin (p = 0.03.) Conclusions: These retrospective data suggest that low-dose radiotherapy fo llowing CR achieved with induction chemotherapy (particularly when document ed with gallium scanning) mag be as effective as higher doses for bulky HD at presentation. Phase III trials are necessary for confirmation of this hy pothesis, (C) 2000 Elsevier Science Inc.