Intensity modulated radiotherapy for localized prostate cancer: rigid compliance to dose-volume constraints as a warranty of acceptable toxicity?

BACKGROUND: To report the toxicity after intensity modulated radiotherapy (IMRT) for patients with localized prostate cancer, as a sole treatment or after radical prostatectomy. METHODS: Between August 2001 and December 2003, 132 patients with prostate cancer were treated with IMRT and 125 were evaluable to acute and late toxicity analysis, after a minimum follow-up time of one year. Clinical and treatment data, including normal tissue dose-volume histogram (DVH) constraints, were reviewed. Gastro-intestinal (GI) and genito-urinary (GU) signs and symptoms were evaluated according to the Radiation Therapy Oncology Group (RTOG) toxicity scales. Median prescribed dose was 76 Gy. Median follow-up time was of 26.1 months. RESULTS: From the 125 patients, 73 (58.4%) presented acute Grade 1 or Grade 2 GI and 97 (77.2%) presented acute Grade 1 or Grade 2 GU toxicity. Grade 3 GI acute toxicity occurred in only 2 patients (1.6%) and Grade 3 GU acute toxicity in only 3 patients (2.4%). Regarding Grade 1 and 2 late toxicity, 26 patients (20.8%) and 21 patients (16.8%) presented GI and GU toxicity, respectively. Grade 2 GI late toxicity occurred in 6 patients (4.8%) and Grade 2 GU late toxicity in 4 patients (3.2%). None patient presented any Grade 3 or higher late toxicity. Non-conformity to DVH constraints occurred in only 11.2% of treatment plans. On univariate analysis, no significant risk factor was identified for Grade 2 GI late toxicity, but mean dose delivered to the PTV was associated to higher Grade 2 GU late toxicity (p = 0.042). CONCLUSION: IMRT is a well tolerable technique for routine treatment of localized prostate cancer, with short and medium-term acceptable toxicity profiles. According to the data presented here, rigid compliance to DHV constraints might prevent higher incidences of normal tissue complication.

Results of high dose rate afterloading brachytherapy boost to conventional external beam radiation therapy for initial and locally advanced prostate cancer.

PURPOSE: To evaluate the impact on biochemical control (bNED), acute and late gastro-intestinal (GI) and urological (GU) morbidity of initial and locally advanced prostate cancer treated with fractionated transrectal ultrasound-guided (TRUS) high dose rate after loading brachytherapy (HDR-B) as a boost to conventional external beam radiation therapy (EBRT). PATIENTS AND METHODS: From March 1997 to February 2000 a total of 119 patients with any of the following characteristics were eligible for study entry: biopsy proven adenocarcinoma Gleason scored (GS), initial prostatic specific antigen (PSA) level dosage 1992 AJCC clinical stage T3a or less, and prostatic volume <60 cc. All patients had prior to HDR-B a course of EBRT 6 MV photons to a median dose of 45 Gy, in 1.8 Gy fractions, to the prostate and seminal vesicles only. HDR-B treatment planning and dosimetric calculations were generated with the Nucletron Planning System. Patients were grouped into two groups, according to their risk for biochemical failure: low-risk group without (LR) or with neoadjuvant total androgen deprivation (AD) prior to EBRT (LR+AD) and high-risk group without (HR) or with neoadjuvant AD (HR+AD), for bNED and dose-escalation protocol. LR encompassed patients who presented GS<6, T1 or T2a and or initial PSA<10 ng/ml, who were treated with 16 Gy (4 Gy fractions, b.i.d.) HDR-B. The remaining patients were grouped into HR or HR+AD and received 20 Gy (5 Gy fractions, b.i.d.) HDR-B. The planning was optimized using the standard geometric optimization. Biological effective doses (BED) for tumor control and late responding tissue were calculated using a alpha/beta ratio of 1.5 and 3 Gy, respectively. They were matched with bNED, acute and late gastrointestinal (GI) and urological (GU) morbidity, according to the RTOG/EORTC scoring criteria. RESULTS: Median age of patients was 68 years (range 47-83), with a median follow-up of 41 months (range 18-48). The crude and actuarial biochemical controls (bNED) in 48 months for all patients were 69.5 and 75.3%, respectively. When grouped into LR, LR+AD, HR and HR+AD the actuarial bNED were 78.2, 76, 76 and 72.3% (P=0.89), respectively. Acute GU and GI morbidity G1-2 were seen in 18.5% (20/108) and 10.2% (11/108) of patients with spontaneous regression. Late GI and GU morbidity G1-2 were seen in 12% (13/108) and 4.6 (5/108) of patients, with no need of intervention. No acute or late G3-4 GU or GI morbidity was seen. CONCLUSIONS: There are many advantages in HDR-B, but the most important ones are the capability of on-line dosimetry, quality control and the procedure being very conformal. There is a low incidence of GU and GI acute and late morbidity with acceptable bNED when treating initial and locally advanced prostate cancer with HDR-B as a boost to EBRT, but we still need to wait for results of phase III open trials that analyze HDR-B and conformal therapy.

Molde plástico de contençäo em radioterapia experimental / A restricting plastic mold for experimental radiotherapy

A imobilizaçäo do paciente durante a irradiaçäo fracionada desempenha um papel fundamental no sucesso do programa radioterápico pré-estabelecido. Essa imobilizaçäo permite aumentar a acuracidade da irradiaçäo pela reproduçäo diária da posiçäo do paciente nas várias sessöes porgramadas, além de diminuir os efeitos colaterais decorrentes da lesäo de tecidos normais adjacentes à área irradiada. Dentro desse contexto, os autores desenvolveram um molde plástico de contençäo para pequenos animais de laboratório, visando a sua imobilizaçäo e permitindo a irradiaçäo seletiva do abdome ou pelve em doses fracionadas. Esse molde apresenta ainda a vantagem de dispensar a administraçäo de altas doses anestésicas aos animais durante o tratamento