Prostate news article, June 2005
| Contribution
of Radiotherapy Volume and Androgen Deprivation to Acute Rectal
and Urinary Toxicity in Patients Undergoing Prostate Cancer
Treatment
Professor Roger S Kirby Visiting Professor to St George's Hospital, London |
 |
Radiotherapy dose escalation provides improved prostate cancer (CaP) outcomes but also increases toxicity. Dr. Peeters and associates from 4 Dutch radiotherapy centres in Amsterdam, Rotterdam, Leeuwarden and Vlissingen report on the acute gastrointestinal (GI) and genitourinary (GU) toxicities in CaP patients undergoing radiotherapy (RT) in the June Epub edition of the Int J Radiat Oncol Biol Phys. Data used was from a Phase III trial comparing 68Gy and 78Gy RT for CaP patients.
Several clinical variables evaluated in a previous clinical report by the authors were deemed to be important prognostic factors for GI and GU toxicity: RT volume effect, neoadjuvant androgen deprivation therapy (NADT), hospital providing treatment and pretreatment GU symptoms.
From the Phase III trial performed between 1997 and 2003, 336 patients receiving either 68 Gy or 78 Gy of conformal RT were included. In general, low risk, regionally advanced and metastatic patients were excluded. Patients were placed in Groups 1-4 with increasing doses of RT given to the peri-prostatic structures due to increasing cancer risk. Acute GI and GU toxicity was serially evaluated based upon the dose-volume given, treating hospital and the duration of NADT (none, <3 months, and >3months). The endpoint was Grade 2 or worse toxicity.
The mean duration of NADT was 1.8 and 4.1 months in the <3 months and >3months groups, respectively. In patients not receiving any NADT, the planning dose volumes of the prostate and seminal vesicles were noted to be significantly larger.
Acute GI Grade 2 or worse toxicity was seen 155 patients (46%), of whom 24 patients experienced Grade 3 toxicity. Patients who received long-term NADT experienced less toxicity (27%) compared with those who received short-term NADT (50%) or no NADT (50%). While GI toxicity did vary by treating hospital, the dosing regimens in Groups 1-4 did not demonstrate a significant difference.
Acute GU toxicity was reported in 190 patients (56%), 49 of them had Grade 3 toxicity. Pretreatment GU symptoms were associated with greater GU toxicity, but interestingly a previous TURP did not significantly impact toxicity outcomes. One-half of patients not treated with NADT had GU toxicity Grade 2 or greater. Patients receiving short-term and long-term NADT had 73% and 71% acute toxicity, respectively. Increasing RT dosage delivered to the bladder surface correlated significantly with acute GU toxicity.
This study suggests that NADT results in less acute GI toxicity but more acute GU toxicity.
Reference: Int J Radiat Oncol Biol Phys 2005, June
2005-07-05