Acute toxicity of conformal high dose interstitial brachytherapy boost in prostate cancer

Over the past few years, brachytherapy has become more and more common in the treatment of prostate cancer, largely thanks to the reduced amount of acute and chronic side effects. At the same time, brachytherapy also allows dose escalation, resulting in significant improvements in the treatment results. From August 2004 to June 2005, we irradiated 40 patients suffering from T1c-T3a prostate cancer. All of the patients underwent external beam radiotherapy with a median dose of 45-50.4 Gy and a conformal high dose interstitial brachytherapy boost (two fractions, 8 Gy per fraction). The patients were divided into three groups: low risk of recurrence (11 patients - 27.5%), intermediate risk (14 patients - 35%) and high risk (15 patients - 37.5%). The medium age of the patients was 68.7 years (between 55 and 77). Hormonal treatment was carried out 17 patients (42.5%). We evaluated the quality of each implantation, including the maximum urethral and rectal dose. The calculated doses were compared with measurements by in vivo dosimetry. Acute toxicity was evaluated in all of the patients according to the Radiation Therapy Oncology Group (RTOG) scale. Each of the patients completed an International Prostatic Symptom Score (IPSS) questionnaire. Acute genitourinary morbidity grade 1 was recorded in 37.5% of patients; grade 2 in 15% of patients. Urine retention in one of the patients resulted in the need to perform an epicystostomy. According to the IPSS score, the majority of patients (90%) experienced an improvement in symptoms related to quality of life. Grade 1 acute gastrointestinal toxicity was recorded in 40% of the patients. Grades 2-4 were not recorded. Here, we show that the combination of external beam radiotherapy and high dose rate (HDR) brachytherapy in the treatment of early prostate cancer to be feasible and well tolerated. Acute toxicity was low and scarcely influenced the quality of life. Among the risk factors of genitourinary toxicity was the volume of the prostate. For gastrointestinal toxicity, risk factors included the combination of HDR brachytherapy and external beam radiotherapy to the pelvis, as well as hormonal treatment.