Purpose: There are limited data on the frequency of second cancer among long-term survivors from Hodgkin's disease. The aim of this study was to determine the frequencies of second cancers, and their locations with respect to radiotherapy portals.
Methods and materials: Medical records of 202 consecutive patients who survived at least for 5 years after treatment for Hodgkin's disease, and who were treated with radiotherapy in Helsinki University Central Hospital between 1970 and 1979, were reviewed. Survival data were collected also from the Finnish Cancer Registry and records of other hospitals. The median follow-up time of the patients still alive was 22 years (range, from 13 to 26). All patients received radiotherapy; in addition, 65 patients received MOPP and 3 received MOPP and ABVD.
Results: During the follow-up consisting of 4020 person-years, 27 patients developed a second cancer. The cumulative risk for a second cancer was 17% (95% CI, from 10.4 to 23.1 %) at 20 years after the diagnosis of Hodgkin's disease. Of the 26, 20 (77%) solid second cancers were found within or adjoining the irradiated fields, and the 20-year cumulative risk for a second cancer within the irradiated fields was 12% (6.3-17.5%). The most common second cancers were lung (n = 7) and breast (n = 4) cancer. In a multivariate analysis, predictive factors for a second cancer were: age at diagnosis greater than the median (30 years, relative risk, 3.97, 1.6-12.5), treatment for recurrent lymphoma (RR, 2.75, 1.3-6.7) and primary treatment without splenectomy (RR 4.31, 1.7-11.0). However, portal size and inclusion of chemotherapy as part of the primary treatment were not significantly associated with second cancer in a univariate analysis.
Conclusion: Patients treated with radiotherapy for Hodgkin's disease have a considerable risk for a second cancer in long-term follow-up. The majority of second cancers arise within or next to the irradiated portals, and particular attention should be paid to the irradiated sites in posttreatment follow-up.