De Novo Malignancies After Kidney Transplant: Where Do We Stand and Does the Head and Neck Region Require More Caution?

The aim of this study was to investigate the characteristics of de novo malignancies arising in kidney transplant recipients followed in a tertiary hospital in Turkey and to examine the tumors in the head and neck region as a subgroup.Data from kidney transplant recipients treated at our institution between January 2010 and July 2022 were retrospectively analyzed in this single-center study. Data regarding malignancies were noted according to the pathologists' reports. In situ malignancies and those arising after graft loss were not evaluated.The study population comprised 231 patients (165 men; 71.4%) with a median follow-up of 11 years (2853 patient-years). The recipients had a higher cancer risk than the general population (standardized incidence rate = 3.04; 95% CI, 1.82-4.26). Thirty de novo malignant tumors were detected in 24 patients (10.4%). The mean age at diagnosis of cancer was 54.88 ± 11.44 years. The median time from transplant to cancer diagnosis was 11.5 years (range, 7-18.8 y). Nonmelanoma skin cancers (56.7% of all tumors) were the most common malignancies. Twenty-two lesions (73.3%) that developed in 17 patients (7.4%) were localized to the head and neck region: 15 (68.2%) were cutaneous and 7 (31.8%) were noncutaneous. The median time from transplant to head and neck cancer diagnosis was 12 years (range, 7.5-17.5 y). Mortality rate was higher in cancer patients (10 [41.7%] vs 17 [8.2%]; P < 0.01).The incidence of de novo malignancy in kidney transplant recipients was relatively higher compared with previous data. Nonmelanoma skin cancers were the most common type. Three-quarters of all lesions were in the head and neck region, and two-thirds were of cutaneous origin.