Background: Few data exist concerning the development of malignancies and haemorrhagic cystitis in patients with systemic autoimmune diseases previously treated with intravenous (iv) cyclophosphamide (CYC). The use of mesna prophylaxis is also controversial.

Methods: The medical records of all patients with chronic systemic inflammatory diseases treated with iv or oral CYC at Stavanger University Hospital from 1985 to 1999 were reviewed. Eighty-five patients were identified, of whom 75 patients had been treated with iv CYC only and were thus included in this study. Of these 75 patients, 20 (27%) had died and 55 (73%) were alive. Forty-two (76%) out of the 55 patients consented to undergo a comprehensive clinical examination, including a cystoscopy in 33 of them. The medical history of the patients not clinically examined was based solely on medical records. Data from the Cancer Registry of Norway and Statistics Norway were used for comparison with normative data in the general population.

Results: Six patients (8%) developed malignant disease compared with an expected number of 4.5, giving a standard incidence ratio of 1.5 [95% confidence interval (CI) 0.7-3.2]. The observed number of deaths was 23 compared to an expected number of 6.3, giving a standard mortality ratio of 3.7 (95% CI 2.4-5.5).

Conclusions: The standard incidence ratio of cancer following iv CYC was increased, although not statistically significantly. No urinary bladder cancer or haemorrhagic cystitis developed even though mesna prophylaxis was not given.