Long-term survival in Hodgkin's disease relative impact of mortality, second tumors, infection, and cardiovascular disease

Abstract

Purpose: Despite dramatic improvements in the survival of patients with Hodgkin's disease attributable to advances in treatment over the past 30 years, concern for the risk of treatment-related deaths has led to a number of trials to evaluate reduction of therapy. The consequences of these trials on recurrence, development of long-term complications, and survival remain unknown. We determined the causes of death in a group of patients with pathologically staged and intensively treated Hodgkin's disease who were followed for long intervals.

Materials and methods: Between April 1969 and December 1988, 794 patients with laparotomy-staged IA to IIIB Hodgkin's disease were treated with radiation therapy alone or combined radiation therapy and chemotherapy. There were 8700 person-years of follow-up (average, 10.95 person-years/ patient). Causes of mortality were grouped into the categories Hodgkin's disease, second malignant tumors, cardiovascular, infection, and miscellaneous. Age- and gender-specific incidence rates were multiplied by corresponding person-years of observation to obtain expected numbers of events. Observed-to-expected results were calculated by type of treatment, age at treatment, sex, and time after Hodgkin's disease. Absolute (excess) risk was expressed as number of excess cases per 10,000 person-years.

Results: Of 124 patients who died, 56 died of Hodgkin's disease, 36 of second malignant neoplasms, 15 of cardiac causes, 9 of infection, and 8 of miscellaneous causes. The 20-year actuarial survival rate for all patients in this study is 73%. Age 40 years or older, mixed cellularity/lymphocyte-depleted histologic type, and stage-III disease were adverse independent predictors of survival. The largest differences were seen by age. The 20-year actuarial rates of survival were 78%, 78%, and 46%, respectively, for patients aged 16 or less, 17 to 39, and 40 years or older at diagnosis. Hodgkin's disease diagnosed at age 40 or older was a significant risk factor for all causes of death. The use of combined chemotherapy/ radiotherapy was a significant risk factor for second tumor and infection-related mortality. The excess risk of death from all causes, including Hodgkin's disease, remained constant with time from treatment and was approximately 1.2% per year over the first 20 years. Deaths from Hodgkin's disease decreased with time from treatment, with no patients dying after 15 years. This decrease, combined with an increased excess mortality risk with time from other causes, especially second tumors, accounted for the constant excess mortality with time after Hodgkin's disease.

Conclusions: Hodgkin's disease followed by second tumors, cardiac events, and infections remain the major causes of death after treatment of Hodgkin's disease. Our findings suggest the importance of both maintaining a high disease-free survival and reducing long-term complications in designing treatments of Hodgkin's disease.