Systemic sclerosis more than doubles risk for cancer
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Patients with systemic sclerosis carry a more than twofold increased risk for cancer — particularly lung, early breast and early melanoma — compared with healthy peers, leading to higher mortality and higher medical costs, according to findings published in Arthritis Care & Research.
“A recent study of American [systemic sclerosis (SSc)] patients postulated that increased cancer risk may be determined by the SSc disease subtype (limited or diffuse), the SSc-specific autoantibody profile, and time since the first SSc clinical manifestation (either Raynaud or non-Raynaud),” Kathleen Morrisroe, MBBS, FRACP, PhD, of the University of Melbourne at St. Vincent’s Hospital, Australia, and colleagues wrote. “These findings are yet to be replicated in other SSc cohorts.”
“Hence, there are no recommended cancer screening guidelines to inform clinicians caring for SSc patients, nor definitive high-risk profiles to aid in identifying those patients at heightened cancer risk,” they added. “Furthermore, the financial burden associated with health service utilization in SSc patients with cancer has not been quantified nor has the impact of cancer on the SSc patient’s already reduced health related quality of life.”
To analyze cancer burden among patients with systemic sclerosis, Morrisroe and colleagues examined 1,727 consecutive participants in the prospective, multicenter Australian Scleroderma Cohort Study (ASCS). The researchers included all adult patients with systemic sclerosis recruited between January 2008 and December 2015, with the ASCS database providing annual comprehensive demographic, disease-related and medication data.
Cancer diagnoses and health care use were analyzed using data linkage through the Australian Institute of Health and Welfare. This allowed ASCS data to merge with Australian state cancer registries, hospital admissions databases, emergency department databases and the Medical Benefit Schedule. The researchers calculated standardized incidence ratios and mortality ratios for patients compared with the general Australian population. In addition, they used Cox proportional hazards regression to determine survival among patients with systemic sclerosis and cancer, compared to those without.
According to the researchers, the 1,727 included patients represented 7,081 person-years of follow-up. The overall cancer incidence was 1.3% per year, with a prevalence of 14.2% (SIR = 2.15; 95% CI, 1.84-2.49). The most common forms of cancer among the patients were breast, melanoma, hematological and lung. RNAP III antibodies were associated with an increased risk for cancer within 5 years of systemic-sclerosis onset (OR = 2.9; P = .044). Calcium channel blockers were associated with a higher risk for overall cancer (OR = 1.47; P = .016), breast cancer (OR = 1.61; P = .051) and melanoma (OR = 2.01; P = .042).
In addition, interstitial lung disease was associated with the development of lung cancer (OR = 2.83; P = .031). Overall, patients with systemic sclerosis who developed cancer demonstrated a more than a twofold increased mortality compared to patients without cancer (HR = 2.85; 95% CI, 1.51-5.37). Those with cancer also spent more health care than those without, with an excess annual health care cost of AU$1,496 (P < .001).
“Through a data linkage study combining a large SSc clinical database with cancer registries, we found that Australian SSc patients have an increased risk of cancer compared with age- and sex-matched population peers, occurring independently of traditional cancer risk factors,” Morrisroe and colleagues wrote. “Those with incident cancer have a two-fold increased all-cause mortality compared to noncancer patients. We highlight the economic burden associated with cancer in a complex multisystem disease and stress the potential role of SSc-specific autoantibodies in profiling cancer risk phenotypes in SSc.” – by Jason Laday
Disclosure: The researchers report funding support from Scleroderma Australia, Arthritis Australia, Actelion Australia, Bayer, CSL Biotherapies, GlaxoSmithKline Australia and Pfizer. Morrisroe reports support from Arthritis Australia and RACP DEV Star Research Establishment Fellowships. Please see the full study for all other authors’ relevant financial disclosures.
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