Objective. To investigate whether systemic lupus erythematosus (SLE) is associated with non-Hodgkin's lymphoma or other malignant neoplasms.
Methods. Data on a cohort of 1,585 patients with SLE from the nationwide Danish Hospital Discharge Register were linked to information in the Danish Cancer Registry to determine the occurrence of cancer during up to 15 years of followup. The expected number of cancers was calculated from accumulated person-years and national cancer incidence rates.
Results. There was a significant excess of non-Hodgkin's lymphoma among the SLE patients, based on 8 cases observed against 1.5 expected (relative risk [RR] 5.2, 95% confidence interval 2.2–10.3). In addition, a significantly increased RR was found for cancer of the lung (RR 1.9; n = 15), the liver (RR 8.0; n = 5), and the vagina/vulva (RR 5.7; n = 3).
Conclusion. There seemed to be a positive association between SLE and non-Hodgkin's lymphoma. Other cancers with a possible virus-related etiology, such as liver and vaginal/vulva cancer, were also observed in excess. In addition, there was an indication of an increased risk of lung cancer among patients who were hospitalized for SLE.