Objective: There is mounting evidence that hematological malignancies are increased in systemic lupus erythematosus (SLE), and the risk of certain solid tumors may also be increased. The pathogenesis may be different for the 2 processes: risk of hematological malignancies in SLE may be due to chronic lymphocyte stimulation, while risk of solid tumors may be influenced by factors such as obesity and reproductive habits. We aimed to determine prevalence in a lupus cohort of selected factors that influence the risk of cancer, and to compare this prevalence to that of the general population.
Methods: Subjects were women followed in the Montreal General Hospital Lupus Clinic. We administered a postal survey of factors known to be associated with lung and aerodigestive cancers (smoking, alcohol use) as well as factors associated with breast and gynecologic cancers (nulliparity, use of oral contraceptives, and hormone replacement therapy). For patients who had died or been lost to followup, data were abstracted from clinic records. Information about nonsteroidal antiinflammatory drug (NSAID) use (a potentially protective factor for colorectal cancer) was also collected. Obesity prevalence was established from the clinic database. Comparison figures were obtained from the 1996-1997 National Population Health Survey data for Quebec women and age adjusted, where possible.
Results: Compared to the general population, the lupus population had lower prevalence of current use of oral contraceptives, and greater prevalence of obesity and nulliparity. The average number of pack-years among smokers was also greater in the lupus cohort.
Conclusion: Solid cancer incidence in SLE may be influenced by established cancer risk factors such as smoking, obesity, and reproductive history.