Cancer risk in amyloidosis patients in Sweden with novel findings on non-Hodgkin lymphoma and skin cancer

Background: Systemic amyloidoses include immunoglobulin light chain (AL) amyloidosis, serum amyloid (AA)-related amyloidosis and senile systemic amyloidosis (SSA). AL amyloidosis is associated with myeloma, and we showed recently that transthyretin-related hereditary amyloidosis was related to non-Hodgkin lymphoma (NHL). In SSA, amyloids constitute wild-type transthyretin. We wanted to analyze cancer risks in amyloidosis, particularly in SSA. Patients and methods: Nonhereditary amyloidosis patients were identified from the Swedish Hospital Discharge and Outpatients Registers from years 1997 through 2010. Their cancer risk was assessed based on the Swedish Cancer Registry using standardized incidence ratio (SIR) between amyloidosis patients and the remaining population. To gain information about amyloidosis subtypes, we used the Swedish Prescribed Drug Register from years 2005 through 2010 to find out the specific medication prescribed. Results: Among 1400 identified amyloidosis patients, cancer risk was increased for myeloma, NHL and squamous cell skin cancer. Myeloma and skin cancers were diagnosed 7-8 years earlier than in the population, whereas NHL was diagnosed in elderly patients. The SIR was 204 for myeloma in patients who received AL amyloidosis medication, and it was 17.22 in patients receiving rheumatoid arthritis medication, suggesting AA amyloidosis. In remaining patients, including SSA, NHL risk was 14.78, including lymphoplasmacytic lymphoma and Waldenstrom macroglobulinemia (51.41) and diffuse large B-cell lymphoma (18.69). In these patients, endometrial cancer (7.04) and cancer of unknown primary site (6.56) were also increased. Conclusions: SSA is likely to be a main cause of NHL in the elderly population. The present findings suggest a novel mechanism for amyloidosis-related cancer, highlighting the role of chronic stimulation by amyloid.