In recent years, there have been repeated reports of an increased risk of malignant degeneration in rheumatics. There are no valid figures for this, but there seems to be evidence of a connection between autoimmune diseases of the rheumatic group and certain tumors - and this could even have an effect on immuno-checkpoint inhibition, one of the most innovative methods of tumor therapy currently available.
A recently published review paper dealt with the possible connection between autoimmune or chronic inflammatory diseases, such as "rheumatism", and malignant tumors. The mechanisms that can be involved are manifold and range from classical autoimmunity, inflammation to immunosuppression in the treatment of rheumatism patients.
Physicians should - at least according to what is known to date - be particularly sensitized to the following topics in rheumatism patients: a partially increased risk of cancer, cancer screening tailored to rheumatic diseases, autoimmune therapies and their possible cancer risks, as well as checkpoint inhibition and its immunomodulating effect.
Inflammatory myopathies are particularly known for increased malignancy rates. In principle, however, it is probably true that other diseases of the so-called rheumatic group also carry different malignancy risks. In part, the cancer risks are related to the stage of the disease, the autoantibodies present or the duration of the disease.
For example, various adenocarcinomas of the gastrointestinal tract, lung or breast, but also non-Hodgkin's lymphoma and other malignancies are associated with inflammatory myopathies. In scleroderma, on the other hand, tumors in the lung, oral cavity or non-melanoma of the skin as well as hematological malignancies occur more frequently.
Patients with rheumatoid arthritis (RA), on the other hand, are more likely to have degenerative lung diseases and lymphomas. Interestingly, the available data also indicate that RA patients may have a lower risk of colo-rectal cancer than the general population.
A similar situation is found in patients suffering from lupus erythematosus (LE). These patients also have a lower risk of e.g. prostate cancer or breast cancer than the general population. However, the cancer risk for lymphomas and HPV-induced tumours, such as cervical cancer, is slightly higher in LE.
One of the best known drugs in rheumatology with an increased risk of cancer is cyclophosphamide. Both the risk of bladder cancer and leukemia increase with increasing dosage. For example, one study showed that a cumulative dose of 36 grams was the highest risk of bladder cancer or acute myeloid leukaemia (AML). In addition, azathioprine, methotrexate and TNF inhibitors appear to increase the risk of skin cancer.
Caution should also be exercised in immunocheckpoint inhibition, according to the authors of the review article: This is increasingly used in more and more tumor diseases in order to break through a tumor escape mechanism and thus make the cancer cells again visible and subject to attack for the immune system. However, an unintended side effect of this immune modulation is in some cases the triggering of rheumatism-similar clinical pictures, which are accompanied by an increased tendency to inflammation. Both, the immune modulation as well as the risk of inflammation, could in turn also have a negative influence on tumor growth in pre-stressed patients.