By Jason Laday
Systemic lupus erythematosus is a risk factor for increased mortality in elderly patients with early breast cancer, according to data published in Arthritis Care & Research.
“Prior research has shown that elderly patients with rheumatoid arthritis with concomitant breast or prostate cancer have increased mortality when compared to patients without rheumatoid arthritis,” Sebastian Bruera, MD, of Baylor College of Medicine, in Houston, and colleagues wrote. “Yet, it is unclear if the same increased risk exists for patients with other autoimmune diseases such as SLE who develop cancer.
“Radiation therapy may conceivably exacerbate SLE flares, and for this reason be withheld from patients with SLE and cancer when compared to patients without SLE,” they added. “Although women with SLE are not at increased risk for developing breast cancer (BC), it is important to evaluate the outcomes of this cancer in this population as it often requires radiation as a treatment modality to improve survival and this may be withheld for women with SLE. Furthermore, as SLE disproportionately affects women more than men at a ratio of 8 to 1, BC is by large the most frequent cancer in patients with SLE.”
To analyze survival in elderly patients with breast cancer and SLE, Bruera and colleagues analyzed data in the Texas Cancer Registry and the Surveillance, Epidemiology, and End Results database. According to the researchers, the Texas Cancer Registry is a statewide, population-based cohort, while the Surveillance, Epidemiology, and End Results database collects information from various state cancer registries — not including the Texas Cancer Registry — with support from the National Cancer Institute. Data collected from these registries were linked to Medicare claims.
For their study, the researchers identified women aged 66 years and older with a histologic diagnosis of breast cancer between 2005 and 2015 and grouped them based on SLE status. Inclusion criteria required enrollment in Medicare Parts A and B, without simultaneous enrollment in an HMO for 1 year prior to cancer diagnosis. Patients with a diagnosis at autopsy or death certificate or a second cancer diagnosis within 1 year of the breast cancer diagnosis were excluded.
Bruera and colleagues identified a total of 494 patients with breast cancer and SLE, and 145,517 patients with breast cancer alone, of whom 9,708 were matched to the SLE group based on age and cancer stage. The researchers estimated overall survival after matching and, in multivariable Cox proportional hazards models, adjusting for other cancer characteristics, treatment and comorbidities. The analysis also included two other cohorts of women — those without cancer, either with or without SLE.
According to the researchers, patients with SLE were less likely to receive radiation, breast-conserving surgery or endocrine therapy. The 8-year overall survival estimate for those with early breast cancer — defined as stages 0-2 — with SLE was 52% (95% CI, 45% to 59%), compared with 74% (95% CI, 73% to 75%) for those without SLE.
In the Cox multivariable model, having both breast cancer and SLE increased the risk for death (HR = 1.65; 95% CI, 1.38-1.98). Patients with breast cancer and SLE also demonstrated an increased risk for death compared with those with SLE but without cancer (HR = 1.42; 95% CI, 1.05-1.92), after adjusting for SLE severity. Patients with SLE and breast cancer received less corticosteroids, antimalarials and immunosuppressants following cancer diagnosis than those without cancer.
“This study reaffirms previous findings that SLE has an impact on comorbidities — such as heart disease, malignancy, etc. — that places these patients at increased risk of death,” Bruera told Healio Rheumatology. “Our study also showed that patients with lupus were less likely to receive radiation and more likely to undergo mastectomy although these differences did not appear to independently impact mortality. Our study also showed that women with SLE and breast cancer were less likely to receive immunosuppressant therapies for their SLE.
“The study points to the need for evidence-based recommendations for the treatment of patients with SLE and concomitant malignancies, with respect to both their cancer and their lupus,” he added. “Careful risk-benefit considerations are necessary when evaluating the need for cancer therapies such as radiation, as well as for the use of immunosuppressants in patients with recently diagnosed malignancies. Our study highlights these differences, but additional research is needed to optimize treatment in these patients.”
Barbara Jacoby is an award winning blogger that has contributed her writings to multiple online publications that have touched readers worldwide.