NEW ORLEANS — Patients with systemic lupus erythematosus have a 50% increased risk of also having skin cancer compared with people who don't have lupus, according to findings from a study involving nearly 500,000 people.
This is the first evidence to link systemic lupus erythematosus (SLE) with skin cancer, although a few prior reports documented an increased risk of breast cancer among female SLE patients, Ritu Khurana, M.D., said at the southern regional meeting of the American Federation for Medical Research.
The new study was done in patients seen at 10 collaborating Veterans Affairs medical centers, and involved a population that was 92% male.
Additional analysis of the same population also showed that patients with progressive, systemic sclerosis had an elevated risk of also having skin cancer or lung cancer.
Several prior reports have linked systemic sclerosis to lung cancer, breast cancer, lymphoproliferative disease, and to cancer in general, said Dr. Khurana, a rheumatologist at Louisiana State University in Shreveport.
The investigators reviewed case records for 484,226 people seen at the 10 VA medical centers during 1998-2004. Their average age was 61 years.
This group included 615 patients diagnosed with SLE, more than 76,000 diagnosed with cancer, and almost 19,000 patients specifically diagnosed with skin cancer (basal cell carcinoma, squamous cell carcinoma, or melanoma).
In a multivariate analysis in which the investigators controlled for smoking history, age, race, and gender, SLE patients were 53% more likely to have skin cancer and 73% more likely to have cancer of any type compared with the other VA patients studied.
The study group also included 203 patients with systemic scleroderma. In the multivariate analysis, patients with scleroderma were 2.35-fold more likely to have lung cancer than the rest of the study population, 82% more likely to have skin cancer, and 61% more likely to have any cancer.
By comparison, patients who smoked had a 2.13-fold elevated risk for developing lung cancer compared with nonsmokers, Dr. Khurana said.
The increased prevalence of cancers in patients with either SLE or systemic sclerosis may be related to the impaired immunosurveillance in these patients, an increase in both systemic and cutaneous inflammation, and an increased susceptibility to viral infections, she said.
Patients with SLE or systemic sclerosis may also have a higher rate of genetic damage, such as chromosomal breaks or deletions.
The elevated risk for skin cancer in patients with SLE or systemic sclerosis means that they should be especially vigilant about sun avoidance and receive regular skin examinations, said Seth M. Berney, M.D., chief of rheumatology at Louisiana State University in Shreveport and a collaborator on these studies.