SUBSEQUENT MALIGNANT NEOPLASMS OF THE KIDNEY AFTER TREATMENT OF PRIMARY MALIGNANCY DURING CHILDHOOD: ANALYSIS OF SURVEILLANCE, EPIDEMIOLOGY, AND END RESULTS DATA FROM 1975 TO 2016

Background: Malignant renal neoplasms are rare before the age of 45. Age, gender, and certain genetic and modifiable risk factors can influence the development these cancers. However, the risk in survivors of childhood cancer is not well established. Methods : Using the SEER registry, we identified survivors of childhood cancer who developed a renal cancer as a subsequent malignant neoplasm (SMN). Original childhood cancer was diagnosed under 20 years of age. We evaluated the clinical characteristics of the survivors of childhood cancer who developed SMNs of the kidney. We calculated standardized incidence ratios and performed Kaplan-Meier estimates to assess survival after SMN of the kidney. Results: We found 53 survivors developed a SMN of the kidney (one patient had 2 subsequent kidney cancers). Of the 54 subsequent kidney cancers, 47 occurred as a second cancer (43 carcinomas, 3 Wilms, and 1 Ewing sarcoma), 6 renal carcinomas occurred as a third cancer and 1 renal carcinoma occurred as a fourth cancer. Of the 53 cancer survivors with SMN of the kidney, 29 were female (54.7%), 47 were white (88.7%) and 7 were Hispanic (13.2%). The most common primary cancers were Hodgkins lymphoma (n=9) and neuroblastoma (n=7). Primary malignancy occurred at a mean age of 10.1 years and SMNs occurred at a mean age of 31.1 years. The overall SIR of developing a subsequent renal cancer was 4.52 (p<0.05; 95%CI 3.39-5.89). The 5-year overall survival after development of a SMN of the kidney was 73% (95%CI: 58%-83%). Conclusions: Subsequent malignant cancers of the kidney are rare but occur ~4.5 times more frequently in survivors of childhood cancer compared to the general population. This increased risk should be considered when providing long-term care for survivors of childhood cancer.