Is there an association of malignancy with systemic lupus erythematosus? An analysis of 276 patients under long-term review.

OBJECTIVE

To estimate the risk of malignancy in a UK cohort of patients with systemic lupus erythematosus (SLE) under long-term review.

METHOD

The University College London Lupus Clinic Database was used to identify a cohort of 276 patients followed up prospectively between 1978 and 1999. Standardized incidence ratios and 95% confidence intervals for all cancers were calculated using age and sex-specific cancer incidence rates for the southeast of England.

RESULTS

In total, 16 malignancies were diagnosed in 15 patients. However, five malignancies were diagnosed before the diagnosis of SLE and were therefore excluded from the final statistical analysis. One case of basal cell carcinoma was also identified, but this was also excluded from the final analysis as no comparable figures were available for the general population. Death as a direct consequence of the malignancy occurred in six (2.3%) patients, accounting for 22.6% of the deaths in our cohort of SLE patients. Compared with the general population, the overall estimated risk for all cancers was not increased in the lupus cohort (standardized incidence rate 1.16 (95% confidence interval 0.55-2. 13). Hodgkin's lymphoma was the only individual cancer that was increased in our cohort of patients [standardized incidence rate 17. 82 (95% confidence interval 0.45-99.23)].

CONCLUSIONS

In our cohort of patients with SLE we did not show an overall increased risk of malignancy. However, SLE was associated with an increased risk of Hodgkin's lymphoma compared with the general population. From our cohort of 276 patients, none of those treated with cyclosporin (3%) developed malignancy, and out of 49 (18%) patients treated with cyclophosphamide only one patient developed malignancy. Out of the 10 patients in the final analysis who developed malignancy, six had treatment with prednisolone, four with azathioprine, five with hydroxychloroquine and only one with cyclophosphamide. No statistical difference in the above cytotoxic therapy was observed between those patients who developed malignancy and those who did not.