Klin Onkol 2006; 19(1): 19-25.
Introduction: Radiotherapy represents one of the basic therapeutic methods in treatment of localized carcinoma of the prostate. The current methodology allows us to increase the irradiation dose to the prostate while lowering the dose distributed to critical organs, particularly the rectum. Optimal irradiation dose is the cornerstone of a successful treatment. Along with local control of the disease and overall survival of the patient, possible acute and long-term side effects need to be monitored very closely, as they markedly influence the quality of the patient’s life. Methods: A non-randomized prospective study comparing the acute genitourinary and gastrointestinal toxicity in patients irradiated for localized carcinoma of the prostate between August 2004 and July 2005. 57 patients treated with conformal external radiotherapy alone represented the first treatment arm (EBRT arm). In the second treatment arm a combination of external radiotherapy and high-dose rate (HDR) brachytherapy (BRT) was employed in 40 patients with localized prostate carcinoma, T1c- T3a (EBRT+BRT arm). All patients underwent conformal external radiotherapy to the pelvic region or the area of prostate and seminal vesicles in the dose of 45 - 50.4 Gy. Brachytherapy in the EBRT+BRT arm was applied in two fractions during the 3rd and the 5th week of external radiotherapy at a dose of 8 Gy per fraction using the interstitial transperineal application technique with Iridium-192 source. Based on the initial PSA levels, Gleason score, and T classification, patients were divided into three groups according to the relapse risk: low risk group (43.9% of the EBRT arm vs. 27.5% of the EBRT+BRT arm, respectively), medium risk group (26.3% vs. 35.0%), and high risk group (29.8% vs. 37.5%). Average age was 69.9 years in the EBRT arm, and 68.7 years in the EBRT+BRT arm. Hormonal manipulation was performed in 36.8% of the EBRT arm, and in 42.5% of the EBRT+BRT arm. The dose volume histogram (DVH) and dose to the anterior rectal wall were evaluated in each patient. Parameters describing the quality of the distribution including the maximum dose to the urethra and rectum were evaluated based on both the calculated and the measured values. Acute toxicity of the treatment was evaluated according to the Radiation Therapy Oncology Group (RTOG) criteria in all patients. Every patient filled out the International Prostate Symptom Score (IPSS) questionnaire both prior to and following the treatment.
Results: EBRT arm: Acute grade 1 genitourinary (GU) toxicity was recorded in 20 patients (35.1%), grade 2 in 13 patients (22.8%), and grade 2-3 in one patient (1.7%). Acute gastrointestinal (GI) toxicity was experienced by 31 patients (54.4%), evaluated as grade 1 toxicity in 16 patients (28.1%), grade 2 in 10 patients (17.5%), and grade 3 in 5 patients (8.8%), respectively. EBRT+BRT arm: Acute grade 1 GU toxicity was recorded in 37.5%, and grade 2 in 15% of the patients. In one patient an epicystostomy was performed due to retention. Symptoms in connection with the treatment subsided within one month from therapy in majority of the patients (90%) according to the IPSS. Only grade 1 acute GI toxicity was recorded in 40% of the patients treated in the EBRT+BRT arm. Conclusion: Acute grade 1 GU toxicity was experienced by a similar percentage of patients in both treatment arms (35.1% vs. 37 .5%). Acute grade 2 GU toxicity according to the RTOG criteria was more frequent in the EBRT arm over the EBRT+BRT arm (22.8% vs. 15%, respectively). Higher acute genitourinary toxicity - grade 3 or 4 - was recorded only in one patient per each treatment arm. Acute GI toxicity was more frequent in the EBRT arm over the EBRT+BRT arm (54.5% vs. 40%). Higher acute GI toxicity - grade 2 and 3 - was only observed in the EBRT arm, not in the EBRT+BRT arm. In our group of patients we demonstrated a very good tolerance of the combined external radiotherapy plus HDR brachytherapy treatment in carcinoma of the prostate. The acute toxicity observed was of low grade and had practically no influence on the quality of life. The size of the prostate was evaluated as the main risk factor for genitourinary toxicity, while the combination of pelvic irradiation with hormonal therapy was assessed as the main risk factor for gastrointestinal toxicity. The combination of external radiotherapy with BRT resulted in a lower incidence of gastrointestinal toxicity than external radiotherapy alone.
