Non-Hodgkin's lymphoma : a search for causes

The aim of this thesis was to investigate some factors of possible importance for the development of non-Hodgkin's lymphoma (NHL), namely ultraviolet (UV) light, maternal and perinatal characteristics, blood transfusions, and smoking. To test the UV light hypothesis, a cohort study of secondary occurrence of skin cancer (malignant melanoma and squamous cell skin cancer) following NHL, and of NHL following skin cancer, was executed. All incident cancers diagnosed between 1943 and 1989 were identified in the nationwide Swedish and Danish cancer registries. Compared to the risks in the general population, the overall risks for squamous cell skin cancer and malignant melanoma subsequent to NHL were significantly elevated 5-9-fold and 2-3-fold respectively. Conversely, the risk for NHL was increased 2-fold following squamous cell skin cancer and increased 40% following malignant melanoma. In a population-based nested case-control study based on 1.7 million births recorded in the nationwide Swedish Birth Registry in 1973 through 1989, record-linkage to the Swedish Cancer Registry disclosed 168 incident childhood NHL cases, for whom 839 individually matched controls were randomly selected. Cesarean section, paracervical blockade and infant endocrine-metabolic disorders were nonsignificantly associated with increased risks of developing NHL before the age of 15 years. Maternal hypertensive diseases were linked with a reduced risk for NHL, although not statistically significantly. In a population-based case-control study, we evaluated the role of blood transfusions within a cohort of 96,795 patients registered in the Swedish Inpatient Registry between1970 and 1983. Follow-up through 1991 in the Cancer Registry revealed 361 incident cases of NHL, for whom 705 individually matched controls were randomly selected. Exposure was assessed through linkage to Transfusion Registries at the respective hospitals. No association was found between blood transfusion and the risk of NHL. To assess the role of smoking in the development of hematolymphoproliferative malignancies, a cohort study including 333,288 men recorded in the Swedish Construction Workers Registry in 1971 through 1991 was designed. Among these, a total of 1,322 incident lymphoid and hematopoietic neoplasms occurred according to the Swedish Cancer Registry. NHL and multiple myeloma showed no association with tobacco use. The risk of developing Hodgkin's disease was slightly elevated, although there was no clear indication of trends with duration. We used the Cancer-Environment Registry III to analyze latitude, a surrogate measure of UV-light exposure, as a determinant of the risk for NHL. Among 10,381 incident cases of NHL, we found an increased risk of NHL associated with a more southern location of the home or workplace