Abstract Background and Aims Neoplasia is considered a risk factor for the development of CKD, for many reasons: aggressive and repeated therapeutic interventions, malnutrition, hyperuricemia and the disease per se. Taking into account the improved cancer survival due to novel therapeutic interventions, the possibility of cancer patients with CKD to reach advanced CKD stages is increasing. The information about cancer patients and CKD is still scarce. This paper tends to fill the gap by analyzing the relation between cancer patients and CKD in a large cancer database from western Romania. Method 5831 patients (3365 female, average age 62.6 +/- 10.4 years, median age 64 years) with neoplasia from a large cancer database in Western Romania have been randomly assigned to this study. Serum creatinine at inclusion was used to estimate baseline GFR by the CKD-Epi formula. During the 2-year follow-up, serum creatinine was repeatedly determined in order to estimate GFR (at least 2 determinations). CKD was defined as eGFR < 60ml/min/1.73m2 persistent for more than 3 months. For our assessment, we used the available personal and medical data from the analyzed database. For comparison, we used the CKD epidemiology data in the general population of Romania. Results GFR < 60ml/min/1.73m2 was identified at inclusion in 11.88% of the cases. The prevalence of CKD according to GFR criteria was 14.49% after the first year of follow-up, significantly higher if compared to the general population (8.8% - 2008) (p<0.0001). In the second year, the prevalence increased to 14.98% (with 3%) and the average decrease of eGFR was 4.7ml/min/year. In the examined database, patients with breast cancers (1317 cases), lung (551), uterus (427), prostate (431) and colonic cancers (498) were dominant. The prevalence of CKD was dependent of the type of cancer, being significantly higher in patients with renal cancer (48,71%), urinary bladder cancers (34,1%), multiple myeloma (20%), liver carcinoma (20%) and pancreatic cancers (19.6%). The prevalence of CKD was significantly lower in patients with rectum cancers (9.9%), testicle cancers 8.8% and in patients with brain tumors (7.1%). The influence of CKD on the survival of cancer patients could not be estimated due to the short follow-up time. Conclusion The prevalence of CKD in patients with neoplasia is higher than in the general population and increasing in time, but according to our results, the rate of decrease of the kidney function is not high. The prevalence of CKD is dependent of the type of cancer being higher in renal, urinary bladder, liver, pancreatic cancers and multiple myeloma and lower in testicle cancers and in brain tumors. Taking in account the increasing survival of cancer patients, the probability to reach ESKD is increasing also and that could influence the profile and needs of patients admitted to renal replacement therapy.