Purpose/Objective: To evaluate the outcome of prostate cancer
patients treated with a combination of HDR Brachytherapy boost
(HDR-BT) and 3D conformal external pelvic radiotherapy (EBRT) in a
dose escalation study.
Materials and Methods: 162 patients were followed between
November 2004 and December 2010 . Two different dose escalation
groups were done: group 1 (n= 92), 1 fraction HDR boost (9-10 Gy )
followed by EBRT (60 Gy in 6 weeks) - BED: 203-216 Gy and group 2
(n=70): 2 fraction HDR boost (18-19 Gy), 6 hours interval between
fractions, followed by EBRT (46 Gy in 4.5 weeks) - BED: 233.3 -247 Gy;
116 pts (71.6%) received concomitant androgen deprivation. Patients
were classified according to the MSKCC criteria into high (N=137) and
intermediate (N=25) risk. Phoenix biochemical failure definition was
used. Toxicity was scored by Radiation Morbidity Scoring Criteria
(RTOG)
Results: The mean follow-up was 41 (range 7-84) months. The 7- years
cancer-specific and overall survival was 100% an 92%, respectively.
The 7 years actuarial biochemical control rate was 89% and 100% for
group 1 and 2, respectively. One patient from group 1 and two
patients from group 2 never reached a low nadir. Two patients
developed distant metastases 12 and 16 months after the treatment.
In a multivariate Cox-regression analysis neither treatment nor risk
group (intermediate vs. high risk) were associated with increased risk
for biochemical failure. The RTOG grade 3 genitourinary early toxicity
was 1.0% and 8.5% while gastrointestinal/genitourinary late toxicity
was 7.6% and 1.4% for group 1 and 2, respectively
Conclusions: HDR BT boost followed by EBRT appears to be a safe,
feasible and effective treatment for patients with unfavorable
localized prostate cancer. This study shows a beneficial effect on
biochemical control in group 2 pts, however without statistical
significance. Higher radiation doses (BED 233.3-247 Gy) do not seem
to carry extra toxicity.