Background

SBRT is becoming an accepted treatment option for low and intermediate risk prostate cancer in the USA despite the lack of randomised evidence. This is based on large cohorts demonstrating excellent clinical outcomes [1-4]. The Royal Marsden (RMH) and Mount Vernon (MVCC) hospitals have both developed prostate SBRT in order to run a RCT comparing SBRT with surgery and SBRT with IMRT (the PACE Trial).

We report our early experience.

Method

Fifty-one patients with low/intermediate risk prostate cancer were treated with 36.25 Gy in 5 fractions at MVCC (26 patients) and RMH (25 patients). All patients completed IPSS and RTOG at each follow-up visit.

41 patients had assessable IPSS data, and all 51 had assessable RTOG data.

38 patients (16 MVCC, 23 RMH) did not receive hormones and were included in the PSA analysis

Results

Median follow-up is 14 months (MVH) and 16 months (RMH). Mean IPSS score rose from 7 at baseline to peak at 11 (2-3 weeks post-treatment). An IPSS rise ≥12 was seen in 22%.

The highest recorded acute GI toxicity for RMH patients was grade 0 (32%), grade 1 (40%) and grade 2 (28%). No late bowel toxicity higher than grade 1 has been noted to date.

The acute GI toxicity for MVH patients (26 patients) was grade 0 (19%), grade 1 (62%), and grade 2 (19%). One patient had a late grade 2 GI toxicity recorded.

Median PSA pre-treatment was 7.5 ng/ml (range 2.6-22) By 12 months post-treatment median PSA is 1.9 ng/ml. There are no biochemical recurrences to date.

Conclusion

The first two NHS centres to deliver prostate SBRT have similar experiences of toxicity and early PSA response and outcomes are encouraging. Compared to conventional fractionation GU symptoms seem to predominate over GI symptoms. Both centres are now recruiting to the PACE trial.