Association between non-Hodgkin lymphoma and renal cell carcinoma

The incidence of patients with multiple primary tumors has been increasing in recent years. The association between non-Hodgkin lymphomas (NHL) and renal cell carcinoma (RCC) is unclear. The presentation of 10 patients with co-existent NHL and RCC at our institution in the past 3 years led us to explore whether this was a chance association or a statistically significant phenomenon. We used the US Surveillance, Epidemiology and End Results (SEER) program (www.seer.cancer.gov) from 1973 to 2006 to identify a total of 892 445 537 subjects aged 18-84, with known values for race and gender at risk for NHL and RCC. Among these, 181 009 were diagnosed with NHL, 118 122 were diagnosed with RCC and 1039 had both NHL and RCC. This was significantly higher than the expected number of 24 with co-existent NHL and RCC (p < 0.0001). The observed number (O) of RCC after NHL was significantly higher than the expected number (E) (O/E: 1.51; 95% confidence interval [CI] 1.36-1.66), with the O/E ratio remaining elevated across the various follow-up time intervals. The observed number of NHL after RCC was not significantly different from the expected number (O/E: 1.09; 95% CI 0.98-1.22). In univariate analyses, race and gender were significantly associated with an increased cumulative incidence of RCC after NHL. Multivariate analysis with age, race and gender revealed that white males had a higher cumulative incidence of RCC after NHL. These findings suggest that patients with NHL are at increased risk for RCC.