Analysis of in-field control and late toxicity for adults with early-stage Hodgkin's disease treated with chemotherapy followed by radiotherapy

Purpose: We analyzed in-field (IF) control in adults with early-stage Hodgkin's disease who received chemotherapy followed by radiotherapy (RT) in terms of the (1) chemotherapeutic regimen used and number of cycles delivered, (2) response to chemotherapy, and (3) initial tumor size. Cardiac toxicity and second malignancies, particularly the incidence of solid tumors in terms of the RT field size treated, were also examined. Methods and Materials: From 1980 to 1995, 286 patients ranging in age from 16 to 88 years (median: 28 years) with Ann Arbor clinical Stage I or II Hodgkin's disease underwent chemotherapy followed 3 to 4 weeks later by RT. There were 516 nodal sites measuring 0.5 to 19.0 cm at the start of chemotherapy, including 134 cases of bulky mediastinal disease. NOVP, MOPP, ABVD, CVPP/ABDIC, and other chemotherapeutic regimens were given to 161, 67, 19, 18, and 21 patients, respectively. Patients received 1-8 (median: 3) cycles of induction chemotherapy. All 533 gross nodal and extranodal sites of disease were included in the RT fields. The median prescribed RT dose for gross disease was 40.0 Gy given in 20 daily 2.0-Gy fractions. There was little variation in the RT dose. Eighty-five patients were treated with involved-field or regional RT (to one side of the diaphragm), and 201 patients were treated with extended-field RT (to both sides of the diaphragm), based on the protocol on which they were enrolled. Results: Follow-up of surviving patients ranged from 1.3 to 19.9 years (median: 7.4 years). Based on a review of simulation films, there were 16 IF, 8 marginal, and 15 out-of-field recurrences. The chemotherapeutic regimen used and the number of cycles of chemotherapy delivered did not significantly affect IF control. IF control also did not significantly depend on the response to induction chemotherapy. In cases where there was a confirmed or unconfirmed complete response as opposed to a partial response or stable disease in response to induction chemotherapy for bulky nodal disease, the 5-year IF control rates were 99% and 92%, respectively (p = 0.0006). The 15-year actuarial risks of coronary artery disease requiring surgical intervention and of solid tumors were 4.1% and 16.8%, respectively. There was a trend toward a greater risk of solid tumors in patients who received extended-field RT rather than involved-field or regional RT (p = 0.08). Conclusions: In patients with nonbulky disease, induction chemotherapy followed by RT to a median dose of 40.0 Gy resulted in excellent IF control, regardless of the chemotherapeutic regimen used, the fact that only 1-2 cycles of chemotherapy were delivered, and the response to chemotherapy. There was a trend toward a higher incidence of solid tumors in patients who received consolidation RT to both sides rather than only one side of the diaphragm. Ongoing Phase III trials will help clarify whether lower RT doses and smaller RT fields after chemotherapy can maintain the IF control seen in our study, but with a lower incidence of late complications in patients with Stage I or II Hodgkin's disease.