Australian patients with systemic sclerosis (SSc) have an increased risk of cancer especially breast, melanoma and lung cancer.

A data linkage study comprising adults in the Australian Scleroderma Cohort Study (ASCS) and information from cancer registries found the cancer risk is also associated with increased mortality and healthcare utilisation.

The study found 14.2% of 1,727 adults recruited to the ASCS between 2008 and 2015 developed cancer, which appeared to be independent of traditional cancer risk factors such as smoking and immunosuppressive therapy.

Standardised incidence ratios compared to the general population were 3.07 for lung cancer, 3.07 for early breast cancer and 3.40 for early melanoma diagnosed within five years of the onset of SSc.

In particular, the study found patients who were RNA polymerase III antibody positive had an almost three fold increased risk of cancer within five years (OR 2.9).

The presence of anticentromere antibodies was found to be protective for lung cancer and the lack of any SSc-specific antibodies was protective for haematological cancer.

The study also found an association between the extended use of calcium channel blockers and overall cancer (OR 1.46, p=0.016), breast cancer (OR 1.61, p=0.051) and melanoma (OR 2.01, p=0.042).

Patients with SSc and cancer had higher all-cause mortality than the general population (Standardised Mortality Ratio 3.13) and compared to SSc patients without cancer (SMR 2.19).

They were also admitted more often to hospital, used ambulatory care service more frequently, and incurred more healthcare costs than SSc patients without cancer.

“The high costs associated with SSc cancer patients highlights the complexity of care required for those with an underlying multisystem condition, such as SSc, who need close and frequent monitoring, with a multidisciplinary approach to care, even in the absence of cancer,” the study said.

The researchers, including Associate Professor Mandy Nikpour from the University of Melbourne and St Vincent’s Hospital Melbourne, said their findings were consistent with meta-analyses.

“The association between the presence of RNAP and early onset cancer has been described in the literature and suggests that its presence should alert the treating clinician to an increased cancer risk phenotype concurrent with SSc onset, thus ensuring that the patients undergo their age-appropriate cancer screening.”

“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,” the study published in Arthritis Care and Research concluded.