Efficacy and dosimetry of computed tomography image-guided 125 I radioactive seed implantation for locally recurrent rectal cancer / 中华放射肿瘤学杂志

ABSTRACT

Objective To evaluate the efficacy of computed tomography ( CT ) image?guided 125 I radioactive seed implantation for locally recurrent rectal cancer ( LRRC ) , and to analyze the relationship between the dosimetry and prognosis. Methods A retrospective analysis was performed on the clinical data of 36 patients with LRRC who received CT image?guided 125 I seed implantation in our hospital from 2003 to 2011. Dosimetric verification was performed using CT scan immediately after 125 I seed implantation. The D90 , D100 , V100 , and V150 values were evaluated. In all the patients, the median activity of seeds was 0?7 mCi (0?4?0?8 mCi) and the median number of implanted seeds was 74(33?137). The local control (LC) and overall survival ( OS ) rates were calculated using the Kaplan?Meier method. The log?rank test and Cox regression model were used for the univariate and multivariate analyses, respectively. Results The median OS time was 16?2 months ( 95% CI= 13?5?18?9 months ) . The median LC time was 10?0 months (95% CI=6?2?13?8 months). The D90 and V100 values were (118.6±25?1) Gy and (90.0±0?3)%, respectively. The univariate analysis suggested that D90 was correlated with the LC time ( P=0?048) and V100 was correlated with the OS time ( P=0?035) . The multivariate analysis showed that a V100 value higher than 90% was a prognostic factor of OS (P=0?044). Conclusions In the treatment of LRRC using CT image?guided 125 I radioactive seed implantation, a D90 value larger than 140 Gy and a V100 value higher than 90% in the postoperative verification plan help improve the LC and OS rates. The D90 and V100 values in the postoperative verification plan may predict treatment outcomes in patients.