Genitourinary Cancers Following Kidney Transplant: Our 20 Years of Experience With Mechanistic Target of Rapamycin Inhibitors.

Objectives: We investigated patients with genitourinary cancer after kidney transplant and the effects of immunosuppression reduction and switching to mechanistic target of rapamycin inhibitors.

Materials And Methods: We retrospectively evaluated kidney transplant recipients seen at our center between January 2000 and January 2020. Patients with <1 year of follow-up were excluded.

Results: Of 827 patients, genitourinary cancer was detected in 11 (1.3%): prostate cancer in 5 patients (45%), renal cell carcinoma in native kidney in 3 (27%), renal cell carcinoma in allograft kidney in 2 (18%), and transitional cell carcinoma of the bladder in 1 (9%). All patients had surgery. Two patients had bone metastasis due to prostate cancer at diagnosis. Two patients had allograft nephrectomy due to de novo renal cell carcinoma. Mean follow-up and age were 97 ± 45 months (range, 26-189) and 50 ± 10.2 years (19% female). After cancer diagnosis, excluding the 2 patients with allograft nephrectomy, immunosuppression was changed in 8 patients (88.8%) (1 patient received the same treatment before and after cancer diagnosis). Six patients received double-drug and 3 received triple-drug protocols. Of 9 patients, 2 were already using mechanistic target of rapamycin inhibitors before cancer diagnosis and 7 were switched: 4 to double-based and 3 to triple-based regimens. Six were switched from tacrolimus. With new treatments, patients showed no progressive kidney failure or rejection (38 ± 40 mo average follow-up). At last follow-up, mean glomerular filtration rate was 62.8 ± 34 mL/min/1.72 m2, which was similar to rate at cancer diagnosis (58.9 ± 24 mL/ min/1.72 m2; P = .78). During follow-up, no patients developed local recurrence of primary tumor or new metastasis, and none showed adverse effects after switch to mechanistic target of rapamycin inhibitors. Three patients died of malignancy-unrelated reasons (ileus, urinary sepsis, heart failure).

Conclusions: Mechanistic target of rapamycin inhibitor-based drugs can be an important maintenance immunosuppressive treatment option for kidney transplant recipients with genitourinary cancers.