Autoimmune diseases increase cancer risk

Link between autoimmune diseases and cancers discovered

10/11/2011

Various autoimmune diseases appear to be directly related to the onset of cancer. The epidemiologist Kari Hemminki from the German Cancer Research Center (DKFZ), together with Swedish colleagues, comes to this conclusion when investigating the „Interaction between 33 different autoimmune diseases and eleven different cancers of the entire digestive tract.“

The scientists of the German Cancer Research Center have investigated possible associations between autoimmune diseases and the occurrence of cancer in the oral cavity, esophagus, gastrointestinal tract, liver and pancreas in a comprehensive study. The DKFZ experts found that most autoimmune diseases are associated with a significantly increased risk of cancer, whereas some autoimmune diseases sometimes reduce the risk of cancer.

The DKFZ researchers, together with their Swedish counterparts, evaluated data from the Swedish Cancer Registry, which recorded a total of 12 million people. The researchers around Kari Hemminki focused on the data of people who had to be hospitalized for an autoimmune disease from 1964 and later in life (up to 2008) suffering from cancer. Due to the large amount of available data, the researchers were also able to consider rare autoimmune diseases as part of their investigation and to analyze a possible connection with the risk of cancer, the experts report in the current issue of the journal „Annals of Oncology“.

Fourfold increased risk of cancer in certain autoimmune diseases
The researchers' calculations indicate that, for example, with a specific form of anemia (pernicious anemia), there is a four-fold higher risk of stomach cancer compared to the average of the population. The autoimmune disease myasthenia gravis, which occurs as a disorder of the neuromuscular transmission of excitation, causes an increased risk of disease even in five different cancers, according to the DKFZ scientists. Accordingly, the risk of esophageal cancer is around three times higher among those affected than the average of the population; the risk of stomach and colon cancer is around 30 percent higher. Other autoimmune diseases associated with an increased risk of multiple cancers in the digestive tract, are Crohn's disease (chronic inflammatory bowel disease), the so-called systemic lupus (autoimmune connective tissue disease), ulcerative colitis (chronic inflammatory bowel disease of the large intestine and colon) and the Psoriasis psoriasis (chronic inflammatory skin disease). For example, autoimmune diseases, in which the risk of cancer is significantly reduced, include rheumatism. Rheumatics, for example, are subject to a 30% reduction in the risk of colorectal cancer, according to the epidemiologists of the DKFZ.

Medication of autoimmune diseases as a cause of altered cancer risk?
As a possible cause of the connection between the occurrence of cancer and diseases in which the immune system fights endogenous structures, called the scientists of the DKFZ the effect of different drugs administered. For example, many of the autoimmune diseases are treated with medicines designed to prevent an excessive response of the immune system and to this end reduce the body's defense mechanisms. As a result, the organism can also fight the tumor cells less well and the risk of cancer increases, the DKFZ experts suspect. The fact that the rheumatics have seen a reduced risk of cancer, the researchers back to the intake of anti-inflammatory drugs. For example, the aspirin drug ASS, which is contained in many rheumatoid drugs, has a cancer-preventing effect, reports Kari Hemminki and colleagues. However, as the most important result of their investigations, the researchers assessed the proven risk increase for cancer in certain autoimmune diseases. Because preventive medical examinations could be adapted in the future especially on this patient circle and „Doctors recommend to their patients with autoimmune diseases to participate regularly in cancer screening programs“, emphasized the DKFZ scientists. (Fp)

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Picture: Uta Herbert