Increasing clinical data supports a low alpha/beta ratio for prostate adenocarcinoma, potentially lower than that of surrounding normal tissues.
A hypofractionated, weekly radiation therapy (RT) schedule should result in improved tumour control, reduced acute toxicity, and similar or decreased late effects. We report the toxicity profile of such treatment.
We conducted a multi-institution phase I/II trial of three-dimensional conformal radiation therapy (3D-CRT) for favourable-risk prostate cancer (T1a-T2a, Gleason [less than or equal to] 6 and PSA < 10). RT consisted of 45 Gy in nine 5 Gy fractions, once weekly. Primary end-points were feasibility and late gastrointestinal (GI) toxicity (RTOG scale), while secondary end-points included acute GI toxicity, acute and late genitourinary (GU) toxicity, biochemical control, and survival.
Between 2006 and 2008, 80 patients were treated. No treatment interruptions occurred. The median follow-up is 33 months (range: 20-51). Maximal grade 1, 2, and 3 acute (< 3 months) GU toxicity was 29%, 31% and 5% respectively (no grade 4). Acute GI grade 1 toxicity was reported in 30% while grade 2 occurred in 14% (no grade 3 or 4). Crude late grade [greater than or equal to] 3 toxicity rates at 31 months were 2% for both GU and GI toxicity. Cumulative late grade [greater than or equal to] 3 GI toxicity at 3 years was 11%. Two patients had PSA failure according to the Phoenix definition. The three-year actuarial biochemical control rate is 97%.
Weekly RT with 45 Gy in 9 fractions is feasible and results in comparable toxicity. Long term tumour control and survival remain to be assessed.
Written by:
Menkarios C, Vigneault E, Brochet N, Nguyen DH, Bahary JP, Jolicoeur M, Beauchemin MC, Villeneuve H, Nguyen TV, Fortin B, Lambert C. Are you the author?
Reference: Radiat Oncol. 2011 Sep 9;6(1):112.
doi: 10.1186/1748-717X-6-112
PubMed Abstract
PMID: 21906281
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