Patients with a certain type of scleroderma may get cancer and scleroderma simultaneously, Johns Hopkins researchers have found, suggesting that in some diseases, autoimmunity and cancer may be linked.

Scleroderma is a complex autoimmune disease, with visible symptoms, affecting the skin, or invisible, affecting internal organs. For some people living with scleroderma, it affects both.

The study may answer what causes scleroderma, an incurable autoimmune disease that causes scar tissue to develop in the skin and in major organ systems, and to pinning down why some with scleroderma appear to be at increased risk of cancer.

The insights add to the growing body of evidence linking some autoimmune disorders with cancer.

Indian American doctor, Ami A Shah, an assistant professor of medicine in the division of rheumatology at the Johns Hopkins University School of Medicine and the study's lead author said, "Our research adds more to the discussion about whether cancer and autoimmune diseases are related and whether cancer may be a trigger for scleroderma."

The small study, which appears online in the journal Arthritis and Rheumatism, looked at blood and tumor samples from 23 patients with both scleroderma and cancer who were treated at the Johns Hopkins Scleroderma Centre.

Ten per cent of the patients treated at the scleroderma centre have cancer as well as the autoimmune disease.

The researchers looked for specific immune markers in each patient, determining which type of antibodies the patients made.

Those with antibodies called anti-RNA polymerase I/III had the most closely related onset of cancer and scleroderma, they found. Those patients got both diseases within two years of one another.

The reasons for the apparent link between scleroderma and cancer are not understood, Shah says. And it is unknown whether cancer could be causing scleroderma or if scleroderma could be causing cancer.

Most often, Shah says, the patients developed cancer first and then scleroderma soon after. She says one theory, as yet unproven, is that as the body generates an immune response to fight a tumor, the immune response could trigger the development of scleroderma.

It is also possible, she says, that the immune response could successfully defeat a developing tumor but still result in scleroderma.

Another possibility could be that organ damage from scleroderma could predispose patients to cancer. Or it could be that the use of immune-suppressing drugs to treat scleroderma could lead to cancer.