BACKGROUND AND OBJECTIVE(#br)This study examines the occurrence of solid tumor (ST) in relation to the different types of therapy (radiotherapy, chemotherapy and radiochemotherapy; splenectomy or splenic irradiation vs no splenectomy-no splenic irradiation) received by patients treated for Hodgkin's disease (HD).(#br)METHODS(#br)The study included 1,045 HD patients treated at the Department of Radiation Oncology, the Institute of Radiology and the Department of Human Biopathology, Hematology Section, University of Rome, "La Sapienza", from 1972 to 1992. For 23% of the patients the follow-up period was longer than 10 years. The average follow-up period was 72 months. For a more accurate calculation of the risk of ST occurrence, the patients were first divided into 3 subgroups according to... initial treatment and then according to the total treatment they had received. Moreover, to establish a probable connection between solid tumor and splenic treatment the patients were also divided into 3 subgroups (splenectomy, splenic irradiation and no splenectomy/no splenic irradiation).(#br)RESULTS(#br)We recorded twenty-four cases of ST after initial treatment. Secondary solid tumor showed a cumulative risk of 0.2% and 13.4% at 5 and 20 years, respectively. After initial treatment with radiotherapy (RT) alone, the cumulative risk was 1.7% and 5.2% at 10 and 20 years, respectively; in the chemotherapy (CT) group, it was 2.4% and 18.1%; in the CT(+)RT group, it was 1.7% and 9%. No statistically significant differences were observed among the different types of treatment (splenectomy, splenic irradiation or no splenectomy/no splenic irradiation) as regards the occurrence of ST. According to multivariate analysis, the most important factor in the risk of ST was age (> 40). Relative risk was 5.2, p = 0.0001.(#br)INTERPRETATION AND CONCLUSIONS(#br)We conclude that an age of over 40 at diagnosis and treatment with CT alone greatly increase the risk of solid tumor occurrence.