Risk Factors of Graft Survival After Diagnosis of Post-kidney Transplant Malignancy: Using Cox Proportional Hazard Model

BACKGROUND: All recipients of kidney transplantation, especially those with posttransplant malignancy, are at risk of long-term graft failure. OBJECTIVES: The purpose of our study was to evaluate the risk factors associated with graft survival after diagnosis of malignancy. PATIENTS AND METHODS: To reach this purpose, we conducted a historical cohort study in Iran and 266 cases with posttransplant malignancy were followed up from diagnosis of malignancy until long-term graft loss or the date of last visit. These patients were taken as a census from 16 Transplant Centers in Iran during 22 years follow-up period since October 1984 to December 2008. A Cox proportional hazards model was performed to determine the important independent predictors of graft survival after malignancy. RESULTS: At the end of the study, long-term graft failure was seen in 27 (10.2%) cases. One-year and 2-year graft survival after diagnosis of cancer were 93.6% and 91.7%, respectively. The univariate analysis showed that the incidence of chronic graft loss was significantly higher in male patients with solid cancers, withdrawal of immunosuppressant regimen, no response to treatment, and tumor metastasis. In continuation, the Cox model indicated that the significant risk factors associated with graft survival were type of cancer (P < 0.0001), response to treatment (P < 0.0001, HR = 0.14, 95% CI: 0.06 - 0.32), metastasis (P < 0.0001, HR = 5.68, 95% CI: 2.24 - 14.42), and treatment modality (P = 0.0001). CONCLUSIONS: By controlling the modifiable risk factors and modality of treatment in our study, physicians can reach more effective treatment.