RISK OF MALIGNANT NEOPLASMS IN PATIENTS WITH PULMONARY SARCOIDOSIS

Background - For over 20 years the association between sarcoidosis and malignancy, particularly lymphoma and lung cancer, has been disputed with mis-classification being the major concern. The aim of the presen t study was to analyse the incidence of malignancies in a cohort of pa tients with sarcoidosis by linkage to a nationwide population based ca ncer register. Methods - The cohort comprised 254 patients followed fo r a median of 25 years until death, emigration, or 31 December 1992, w hichever came first. The expected number of cancer cases was calculate d using the annual age and sex specific cancer rates from the Danish C ancer Registry. Results - Thirty six cancers were registered, three of which were misclassified as sarcoidosis, leaving 33 cancers compared with 23 expected (standardised incidence ratio (SIR) = 1.4; 95% CI 0.9 9 to 2.0). Five lung cancers were observed compared with 2.5 expected, yielding an SIR of 2.0 (95% CI 0.7 to 4.7). There was no incidence of lymphoma and only one case of leukaemia. There was a significant exce ss number of pharyngeal cancers based on two cases (SIR=15.4; 95% CE 1 .7 to 56). Conclusions - This study does not support the theory of an association between sarcoidosis and malignancy, and the main reason ot her studies have shown such an association is most likely to have been due to selection bias and misclassification.