Sep. 01, 2011

Women with Lupus Have Decreased Risk for Certain Cancers

Breast, ovarian, and endometrial malignancies in systemic lupus erythematosus: a meta-analysis
Bernatsky S, Ramsey-Goldman R, Foulkes WD, Gordon C, and Clarke AE. (2011).British Journal of Cancer 104:1478-1481.

What is the topic?

Cancer risk in lupus is an important topic. Little attention has been focused on women's cancers (i.e., breast, ovarian, and endometrial cancers), even though lupus affects mostly women. Up to now, there have been relatively few studies of the development of these cancers in women with lupus.

What did the researchers hope to learn?

The researchers aimed to estimate the risk of breast, endometrial, and ovarian cancers in women with lupus relative to that for the general population. 

Who was studied?

The study included information obtained about over 47,000 lupus patients. Of these, over 42,000 were women. 

How was the study conducted?

The researchers conducted an extensive literature review and located all relevant articles about cancer risk in people with lupus published since 1995. These included large, international cohort studies with similar follow-up times, including those in the United States, Denmark, and South Korea. This was an effective strategy since most of the articles about cancer risk in lupus have been published in the last 10-15 years. 

The total number of cancers observed across studies was summed for each cancer type of interest. The expected number of cancers was also determined based on general population cancer rates. Patients who contributed a cancer of one type could also still contribute to other cancer types. Patients with a history of previous cancers were included, but cancers occurring prior to a diagnosis of lupus were excluded. 

What did the researchers find?

In the lupus patients included in this study, there were 376 breast cancers, 66 endometrial cancers, and 44 ovarian cancers. In each case, the number of cancers that occurred was far lower than that which would be expected based on general population cancer rates. This suggests that women with lupus have a much lower risk for these types of cancer compared to the age-matched general population of women. 

What were the limitations of the study?

Most of the patients in the study cohorts included here were Caucasian. While cancer profiles may be influenced by race, the current research did not stratify cancer risk by race. The study could also not address whether the use of immunosuppressive agents was associated with higher rates of cancer in the lupus patients. 

What do the results means for you?

The reduced incidence of breast, endometrial, and ovarian cancers in women with lupus may be due to inherent differences in women with lupus (vs. the general population) with respect to estrogen levels and/or genetic makeup. Further studies will be required before the reasons for the observed outcomes can be definitively determined. Meanwhile, women with lupus should continue to undergo regular screening according to general population guidelines.