Comparison of two treatment approaches for prostate cancer: intensity-modulated radiation therapy combined with 125I seed-implant brachytherapy or 125I seed-implant brachytherapy alone

Abstract

The purpose of the present study was to assess the results of two different treatment approaches for clinically localized prostate cancer: intensity-modulated radiation therapy (IMRT) followed by 125I seed-implant brachytherapy and 125I seed-implant brachytherapy alone. We studied our 30 most recent consecutive patients. The sample population consisted of 15 cases treated with IMRT (50.4 Gy) followed by 125I seed-implant boost (95 Gy), and 15 cases treated with 125I seed implant only (144 Gy). We analyzed established dosimetric indices and various clinical parameters. In addition, we also evaluated and compared the acute urinary morbidities of the two treatment approaches, as assessed by the international prostate symptom score (IPSS). In our series, acute urinary morbidity was slightly increased with IMRT followed by 125I seed-implant brachytherapy as compared with 125I seed-implant brachytherapy alone. In addition, we observed no statistically significant correlation between the IPSS and the maximum or mean urethral dose. The combination of IMRT and seed-implant brachytherapy presents an alternative opportunity to treat clinically localized prostate cancer. The full potential of the procedure needs to be further investigated.

Figure 1

Typical isodose distribution for a representative transverse slice of an intensity‐modulated radiation therapy plan. The red and green contours represent the planning target volume (PTV) and the urethra respectively. The maximum urethral dose was $100\mathrm{\%}$ of the prescribed dose, thus creating a circular low‐dose region around the urethra.

Figure 2

The 95‐Gy prescription isodose line (green) for a representative seed implant plan computed for the patient shown in Fig. 1. The pink squares indicate needles used for seed deposition. Three seeds were implanted in this particular slice, as indicated by three small white dots.