Lupus linked to increased cancer risk

A large, long-term study has confirmed an increased risk of cancer in patients with Systemic lupus erythematosus (SLE), who are 15 percent more likely to develop any type of malignancy compared with individuals in general population, Dr. S. Bernatsky of Montreal General Hospital and colleagues report.

The risk of developing a blood-related cancer was almost three times as high, and for non-Hodgkin's lymphoma, specifically, it was almost four times as high. The findings also indicate a more than double risk of liver-related cancers and a 37 percent increased risk of lung cancer in SLE patients.

Evidence has been growing that SLE may increase the risk of certain cancers, Bernatsky and colleagues note in the journal Arthritis and Rheumatism. A number of explanations have been proposed, they add, including medication use, higher prevalence of lifestyle-related risk factors and abnormalities of the immune system.

The current study, the largest by far to date of a group of SLE patients, included almost 10,000 subjects. During the follow-up period, which averaged 8 years, 431 cases of cancer were diagnosed. The researchers compared the incidence of cancer among these patients with expected rates in the general population, matched by age, sex, time period and geographic area.

In addition to finding an overall increased cancer risk, the researchers found that the risk of developing cancer was greatest in the first year after SLE was diagnosed.

Patients and physicians should take note of the findings, the researchers point out. Symptoms that could be associated with a blood-related cancer, such as weight loss or swollen lymph nodes, should not be too quickly attributed to SLE, they advise.

Further cooperative studies are underway, the researchers add, to attempt to identify factors responsible for the SLE-malignancy relationship.

SOURCE: Arthritis and Rheumatism May 2005.