Abstract
To review recent advances and current controversies on the association between systemic sclerosis (SSc) and cancer, PUBMED was searched from 1966 to the present using the terms: systemic sclerosis, cancer, morphoea, sclerotic diseases. Malignancies, mainly in lung and breast, coexist with idiopathic SSc or with SSc-like disorders, but not with localized forms of scleroderma (morphoea), with the exception of squamous cell carcinoma in patients with pansclerotic morphoea and skin ulcers. The mechanisms connecting SSc and malignancies are unknown. The occurrence of different cancer types with SSc or SSc-like disorders suggest different underlying mechanisms, including altered immune response, common genetic and environmental links, disease-dependent factors, tumor-derived biologic substances and therapies. The process of sclerosis itself may favour cancer in certain sites, and a reaction between T cells and neoantigens formed during irradiation has been suggested to explain the frequent development of morphoea after breast irradiation. Radiotherapy, especially when used for breast cancer, may trigger idiopathic SSc or morphoea and influence the severity of preexisting SSc, with the consequence that SSc is considered a relative contraindication to breast radiotherapy. In conclusion, cancer and SSc may be associated, but it is still controversial as to whether there is a causal relationship. Continuing interest in these associations, in particular in the different modalities of associations, may help to understand the underlying biological mechanisms and to identify patients at risk.