Comparing cystatin C changes as a measure of renal function before and after radiotherapy in patients with stomach Cancer

ABSTRACT

The objective of this study was to determine and compare Cystatin C changes before and after radiotherapy in patients with stomach cancer who were candidate for radiotherapy. This study was conducted as a prospective cohort one. Eighteen patients with definite diagnosis of stomach cancer under treatment by radiotherapy who presented to Radiotherapy-Oncology Center of Imam Hossein Hospital, Tehran-Iran, and the treatment in all cases was simultaneous chemoradiation with Xeloda were included. In all patients before radiotherapy and after radiotherapy serum creatinine [Cr] and Cystatin C were measured simultaneously. Mean cystatin level before treatment [1.2 +/- 0.4] was significantly lower than that of post-treatment [1.6 +/- 0.36], [P=0.001]. Serum Cr level before treatment was 1.15 +/- 0.33 and after radiotherapy was 1.08 +/- 0.24 and did not show significant difference. Glomerular filtration rate [GFR] of the patients before radiotherapy was-46.8 +/- 21.0 and after radiotherapy was 43.8 +/- 15.8 that did not have significant difference [P=0.146] and also blood urea nitrogen [BUN] before radiotherapy was 20.72 +/- 3.7 and 20 +/- 6.38 after radiotherapy that did not have significant difference [P=0.6]. Comparison of the Cystatin C difference with total radiation dose of the kidneys that are put in three dose groups in radiotherapy field had association that in dose of less that 18 gray [Gy] the Cystatin C change showed significant and positive association [P=0.027; r=0.52] and about 18-24 Gy the Cystatin C difference showed significant and negative association [P=0.023, r=-0.53]. It seems that for evaluating the renal function, serum Cystatin C measurement is preferable than serum Cr. level