Cystic kidney diseases and toxic
interstitial nephritis may be complicated by renal
tumors. Long-term
lithium intake is associated with
tubulointerstitial nephritis and renal
cysts but to date such an association with
tumors has not been determined. We evaluated this in a retrospective study to determine whether
lithium-treated patients were at higher risk of renal
tumors compared with
lithium-free patients with
chronic kidney disease (CKD), and to the general population. Over a 16-year period, 14 of 170
lithium-treated patients had renal
tumors, including seven malignant and seven benign
tumors. The mean duration of
lithium exposure at diagnosis was 21.4 years. The
renal cancers included three clear-cell and two papillary
renal cell carcinomas, one hybrid
tumor with chromophobe and
oncocytoma characteristics, and one clear-cell
carcinoma with leiomyomatous stroma. The benign
tumors included four oncocytomas, one mixed epithelial and stromal
tumor, and two
angiomyolipomas. The percentage of renal
tumors, particularly
cancers and oncocytomas, was significantly higher in
lithium-treated patients compared with 340 gender-, age-, and estimated glomerular filtration rate (eGFR)-matched
lithium-free patients. Additionally, the Standardized Incidence Ratio of
renal cancer was significantly higher in
lithium-treated patients compared with the general population: 7.51 (95% confidence interval (CI) (1.51-21.95)) and 13.69 (95% CI (3.68-35.06)) in men and women, respectively. Thus, there is an increased risk of renal
tumors in
lithium-treated patients.