RESUMEN
PURPOSE: To compare biochemical recurrence-free survival (BRFS) and toxicity outcomes of high dose rate brachytherapy (HDRB) and stereotactic body radiotherapy (SBRT) boost after elective nodal irradiation for high/very high-risk prostate cancer. MATERIALS AND METHODS: a retrospective analysis was performed in 149 male. In 98 patients, the boost to the prostate was delivered by HDRB as 2 fractions of 10 Gy (EQD2 for α/ß = 1.5; 66 Gy) or 1 fraction of 15 Gy (EQD2 for α/ß = 1.5; 71 Gy). In 51 male, SBRT was used for the boost delivery (3 fractions of 7 Gy; EQD2Gy for α/ß = 1.5; 51 Gy) because brachytherapy equipment was out of order. RESULTS: In 98 patients that received HDRB boost, 3- and 5-year BRFS were 74.6% and 66.8%. Late grade-II genitourinary toxicity was detected in 27, grade-III in 1 case. Grade-II (maximum) rectal toxicity was diagnosed in nine patients. For 51 male patients that received SBRT boost, 3- and 5-year BRFS was 76.5% and 67.7%. Late grade-II (maximum) genitourinary toxicity was detected in five cases, late grade-II rectal toxicity in four cases. Other three patients developed late grade-III-IV rectal toxicity that required diverting colostomy. SBRT boost was associated with higher maximum dose to 2 cm3 of anterior rectal wall (D2cm³rectum) compared to HDRB: 92% versus 55% of dose to prostate. Severe rectal toxicity was negligible at EQD2 D2cm³rectum <85 Gy and EQD2 D5cm³ rectum <75 Gy. CONCLUSION: Our results indicate similar 3- and 5-year BRFS in patients with high/very high-risk prostate cancer who received HDRB or SBRT boost, but SBRT boost is associated with higher rate of severe late rectal toxicity.
RESUMEN
PURPOSE: The aim of this work is to evaluate results of prostate transperineal saturation biopsy as a guide for focal high-dose-rate brachytherapy in patients with prostate cancer (PCa). MATERIAL AND METHODS: Template guided saturation biopsy was performed in 67 primary patients with suspicion for prostate cancer. Biopsy was performed under ultrasonography (US) control with the help of brachytherapy grid and 5 mm distance between samples. We put special attention for accurate sampling of prostate in periurethral region. The number of cores varied from 17 to 81 (average 36 cores). Finally, in 40 patients with confirmed prostate cancer results of biopsy were used for brachytherapy planning. RESULTS: Saturation biopsy revealed prostate cancer in 40 of 67 evaluated patients. The extent of biopsy core involvement varied from 5% to 100% (average: 57%). Focal nature of PCa (single unilateral tumor nodule) was diagnosed in 10 (25%), multifocal - in another 30 (75%) patients. Hemigland invasion was mentioned in 12 (30%) cases. Saturation biopsy detected PCa in periurethral cores in 27 (67.5%) of 40 evaluated patients. In 10 patients, the extent of involvement in periurethral cores varied between 10% and 50%; in another, 17 observations exceeded 50%. According to results obtained on saturation biopsy, we performed HDR brachytherapy with "urethra low dose tunnel" (D10ur ≤ 80-90%) in 13 patients with noninvolved periurethral cores. Theoretically, hemigland brachytherapy was possible in 12 of 40 evaluated patients with PCa. CONCLUSIONS: In low risk patients with PCa results of template guided saturation biopsy indicates high frequency (75%) of multifocal disease and high probability (67.5%) of periurethral invasion. Suitable candidates for focal HDR brachytherapy or irradiation with additional sparing of urethra can be effectively determined with the help of saturation biopsy.
