Abstract
The StockholmโGotland Cancer Register was used to evaluate the clinical observation that patients with nonโHodgkin's lymphoma (NHL) had an increased risk of malignant melanoma or squamousโcell carcinoma of the skin (SCCS) and vice verso. During 1958โ1992, NHL was diagnosed in a total of 6,176 patients. Of these patients, 504 developed a second primary cancer of any type except NHL, compared to 301.9 expected, giving a standardized incidence ratio (SIR) of 1.7 [95% confidence interval (Cl) 1.5โ1.8]. The risk of SCCS and malignant melanoma in patients with NHL was 4.8 (95% Cl 3.6โ6.2; n = 54) and 1.7 (95% Cl 0.8โ3.1; n = 10), respectively. The hazard risk for a second malignancy was relatively constant over time, whereas the skin malignancies revealed the highest risks 3โ10 years after initial diagnosis. Similarly, the risk of a secondary NHL was studied in patients with malignant melanoma and SCCS during the same period and found to be 1.3 (95% Cl 0.8โ2.1; n = 17) and 1.8 (95% Cl 1.2โ2.5; n = 34), respectively. The highest risk for NHL following malignant melanoma was seen 3โ10 years after first diagnosis, while the highest risk following SCCS was observed 0โ2 years after initial diagnosis. One of several possible explanations for the development of NHL and a skin malignancy in the same patient is an immunological defect caused by sun exposure. ยฉ 1995 WileyโLiss, Inc.