Breast cancer in systemic lupus erythematosus (SLE): receptor status and treatment

Objective There is a decreased risk of breast cancer in systemic lupus erythematosus (SLE) versus the general population; little is known regarding the receptor status of breast cancers in SLE, or treatment. Methods Breast cancer cases occurring after SLE diagnosis were ascertained through linkage with tumor registries. We determined breast cancer positivity for estrogen receptors (ER), progesterone receptors (PR), and/or Human Epidermal Growth Factor Receptor 2 (HER2), as well as cancer treatment. Results We obtained information on ER, PR, and/or HER2 status for 63 SLE patients with breast cancer. Fifty-three had information on ER and/or PR status; 36 of these (69%) were ER positive. Thirty-six of the 63 had information on HER2 status; of these, 26 had complete information on all three receptors. Twenty-one of these 26 (81%) were HER2 negative; seven of 26(27%) were triple negative. All but one patient underwent surgery; 11.5% received both non-tamoxifen chemotherapy and radiotherapy, 16.4% radiotherapy without non-tamoxifen chemotherapy, and 14.7% received non-tamoxifen chemotherapy without radiotherapy. Conclusion ER positivity was similar to historical general population figures, with a trend toward a higher proportion of triple-negative breast cancers in SLE (possibly reflecting the relatively young age of our SLE patients).