Three-Dimensional Conformal Therapy Versus Standard Radiation Therapy in Localized Carcinoma of Prostate: An Update

Patterns of treatment failure in patients with prostate cancer treated with 76-80 Gy radiotherapy to the prostate and seminal vesicles ± hormonotherapy

PURPOSE

To assess the pattern of treatment failure in patients with prostate cancer (PCa) treated with radiotherapy (76-80 Gy) ± hormone therapy (HT). We also evaluated the influence of treatment failure on survival outcomes.

METHODS

Retrospective study of patients with PCa (n = 302) treated with radiotherapy (RT) ± HT at our centre between November 1999 and July 2007. The mean patient age was 70.2 years (range 51-87). Distribution by NCCN risk group was low (n = 80, 26.5%), intermediate (n = 86, 28.5%), high (n = 77, 25.5%), and very high (n = 49, 16.2%). Most patients (n = 273, 90.4%) received IMRT at a dose of 76-80 Gy. HT was administered in 237 patients (78.5%), in most cases (n = 167, 55.3%) for < 7 months RESULTS: Survival rates at 10 years were: overall survival (OS), 64.3%; biochemical disease-free survival, 83.9%; disease-free survival, 92.5%; and metastasis-free survival (MFS), 94.3%. Biochemical failure (BF) was observed in 55 cases (18.2%), 32 of whom subsequently developed clinical recurrence: metastasis (n = 17, 5.6%), local failure (n = 11, 3.6%), and regional failure (n = 4, 1.3%). The cause of death (n = 159) was intercurrent disease in 115 cases (72.3%), second cancer in 27 (17.0%), and PCa in 17 (10.7%). Biochemical failure-free survival ≤ 24 months was significantly associated with worse OS and MFS (p = 0.0001). Late genitourinary and gastrointestinal toxicity grade ≥ 3 (RTOG) was observed in 18 (6.0%) and 7 (2.3%) patients, respectively.

CONCLUSIONS

The main type of treatment failure after 76-80 Gy of radiotherapy ± HT is local or metastatic. In all cases, biochemical failure occurred prior to treatment failure. BF within 24 months of treatment completion was significantly associated with worse OS and MFS.

Dose distribution in 3-dimensional conformal radiotherapy for prostate cancer: comparison of femur doses for four treatment techniques

Purpose: Conformal radiotherapy of the prostate is an increasingly common technique in the treatment of prostate cancer. When using 3D conformal radiotherapy (CFRT) methods, it is desirable to protect the vital structures such as bladder, rectum, and femur. In this study, our aim was to compare the femur head doses resulting from co-planar beam arrangements in four-field (4F), five-field (5F), six-field (6F) and seven-field (7F) treatment plans, in a dose-escalated CFRT schedule.

Materials and Methods: From January 2005 to December 2006, at Istanbul University Medical Faculty of Radiation Oncology Clinic, a total of 22 patients with carcinoma of the prostate had been scanned using computed tomography (CT) (0.50 mm) in the supine position. During the CT scanning which used the Sim Pro (CMD–USA) programme, planned target volume (PTV), clinical target volume (CTV), and dose volumes received by the bladder, rectum and femur heads were recorded and dose–volume histogram (DVH) were created. The dose volume relating to prostate and seminal vesicles was termed CTV 1, and the dose volume relating to prostate alone was termed CTV 2. During the formation of PTV, into CTV 1, from the anterior-superior-inferior 8 mm, and from posterior 5 mm tolerance were taken into account. After volume determination is calculated using XiO (CMS-USA) 3D treatment planning computer, each patient 4F (45° – 25%, 135° – 25%, 225° – 25%, 315° – 25%), 5F (0° – 20%, 45° – 20%, 90° – 20%, 270° – 20%, 315° – 20%), 6F (45° – 20%, 90° – 10%, 135° 20%, 315° – 20%, 270° – 10%, 225° – 20%) and 7F (0° – 4%, 45° – 12.9%, 90° – 22.2%, 135° – 12.9%, 315° – 12.9%, 270° – 22.2%, 225° – 12.9%) was entered; 70 – 76 Gy was calculated to be given to prostate lodge. With the use of Siemes Oncor, 18 MV photons CFRT was applied. In DVH analysis, following were observed: V50, minimum and maximum doses for head of left femur and right femur total doses.

Results: Our statistical evaluation was made using SPSS software, and we found femur doses following; 4F V50 1030 cGy (minimum 58, maximum 1390), 5F V50 2425 cGy (minimum 540, maximum 3631), 6F V50 1769 cGy (minimum 1234, maximum 3912) and 7F V50 3230 cGy (minimum 2150, maximum 4137). In comparing different techniques, the greatest rectal sparing was achieved by the 5F plan. (Rectal: 5F V%25 = 59.90 ± 6.8 Gy, 4F V%25 = 62.30 ± 10.3 Gy, 6F V%25 = 69.36 ± 5.7 Gy, 7F V%25 = 61.32 ± 7.3 Gy). The greatest femoral head sparing was achieved by the 4F techniques. When paired samples t-test was made, we found considerable lower femur doses for 4F techniques (p = 0.05).

Conclusion: We concluded that, during radiotherapy to treat carcinoma of the prostate, the dose received by the rectum is the most important factor to consider, given the potential for late toxicity in this organ. However, while using lateral fields (90–270°) so as to protect the rectum, the doses received by the femur heads were observed to be higher. Especially in older patients, the critical doses of 52 Gy for TD5/5 and 65 Gy for TD 50/5 were observed to be not reached late toxicity for 4F, 5F, 6F and 7F.

Análise comparativa dos histogramas de dose e volume entre planejamentos tridimensionais conformados e convencionais não conformados na radioterapia do câncer de próstata

OBJETIVO: Analisar, comparativamente, doses de radiação em volumes alvos e órgãos de risco entre planejamentos conformados e não conformados em pacientes com câncer de próstata. MATERIAIS E MÉTODOS: No presente trabalho foram analisados planejamentos de 40 pacientes portadores de câncer de próstata. Foram realizados planejamentos conformados, não conformados isocêntricos e não conformados utilizando a distância fonte-superfície, simulados para cada caso, para comparação das doses em volumes alvos e órgãos de risco. Para a comparação foram analisados os histogramas de dose e volume para volumes alvos e órgãos de risco. RESULTADOS: As medianas das doses foram significativamente menores no planejamento conformado analisando-se os seguintes volumes no reto: 25%, 40% e 60%. As medianas das doses foram significativamente menores no planejamento conformado analisando-se os seguintes volumes na bexiga: 30% e 60%. As doses medianas foram significativamente menores no planejamento conformado analisando-se as articulações coxofemorais direita e esquerda. As doses máximas, médias e medianas no volume alvo clínico e no volume alvo planejado foram significativamente maiores no planejamento conformado. CONCLUSÃO: O presente estudo demonstrou que por meio do planejamento conformado em pacientes com câncer de próstata é possível entregar doses maiores no volume alvo e doses menores em órgãos de risco.

Forward-planning intensity-modulated radiotherapy technique for prostate cancer

In this study, we present an intensity‐modulated radiotherapy technique based on forward planning dose calculations to provide a concave dose distribution to the prostate and seminal vesicles by means of modified dynamic arc therapy (M‐DAT). Dynamic arcs (350 degrees) conforming to the beam's eye view of the prostate and seminal vesicles while shielding the rectum, combined with two lateral oblique conformal fields (15 degrees with respect to laterals) fitting the prostate only, were applied to deliver doses of 78 Gy and 61.23 Gy in 39 fractions to the prostate and seminal vesicles respectively. Dynamic wedges (45 degrees of thick end, anteriorly oriented) were used with conformal beams to adjust the dose homogeneity to the prostate, although in some cases, hard wedges (30 degrees of thick part, inferiorly oriented) were used with arcs to adjust the dose coverage to the seminal vesicles. The M‐DAT was applied to 10 patients in supine and 10 patients in prone positioning to determine the proper patient positioning for optimum protection of the rectum. The M‐DAT was compared with the simplified intensity‐modulated arc therapy (SIMAT) technique, composed of three phases of bilateral dynamic arcs. The mean rectal dose in M‐DAT for prone patients was 22.5±5.1 Gy; in M‐DAT and SIMAT for supine patients, it was 30.2±5.1 Gy and 39.4±6.0 Gy respectively. The doses to 15%, 25%, 35%, and 50% of the rectum volume in M‐DAT for prone patients were 44.5±10.2 Gy, 33.0±8.2 Gy, 25.3±6.4 Gy, and 16.3±5.6 Gy respectively. These values were lower than those in M‐DAT and in SIMAT for supine patients by 7.7%, 18.2%, 22.4%, and 28.5% and by 25.0%, 32.1%, 34.9%, and 41.9% of the prescribed dose (78 Gy) respectively. Ion chamber measurements showed good agreement of the calculated and measured isocentric dose (maximum deviation of 3.5%). Accuracy of the dose distribution calculation was evaluated by film dosimetry using a gamma index, allowing 3% dose variation and 4 mm distance to agreement as the individual acceptance criteria in prostate and seminal vesicle levels alike for all supine and prone patients. We found that fewer than 10% of the pixels in the dose distribution of the calculated area of 10×10−cm failed the acceptance criteria. These pixels were observed mainly in the low‐dose regions, particularly at the level of the seminal vesicles.

In conclusion, the single‐phase M‐DAT technique with patients in the prone position was found to provide the intended coverage of the prescribed doses to the prostate and seminal vesicles with improved protection for the rectum. Accordingly, M‐DAT has replaced non‐modulated conformal radiotherapy or SIMAT as the standard treatment for prostate cancer in our department.

PACS number: 87.53.Tf

Treatment of a radiation-induced rectal ulcer with hyperbaric oxygen therapy in a man with prostate cancer

Late radiation proctopathy is a painful and vexing complication of prostate radiation. We report a case of a 55-year-old man with prostate cancer, and complaints of tenesmus and severe rectal pain after radiation therapy. The patient was diagnosed with a locally advanced Gleason score 8 prostate cancer and an increased prostate-specific antigen of 42.3 ng/ml. His past medical history was notable for a history of bilateral lymph node dissection complicated by Clostridium difficile colitis. He subsequently received 3-dimensional conformal radiation therapy. Seven months after completing therapy, minor rectal bleeding and significant pain developed, requiring increasing doses of opioid analgesics. Fourteen months after 3-dimensional conformal radiation therapy, sigmoidoscopy revealed a single chronic deep ulcer at the anorectal junction. As an alternative to diverting colostomy, the patient underwent a course of hyperbaric oxygen. Within 1 month of completing hyperbaric oxygen treatment, his symptoms completely resolved. Nine months from completion of hyperbaric oxygen therapy, he has had no recurrence of symptoms. Hyperbaric oxygen therapy can be considered a treatment option after failure of standard treatments in patients with severe radiation proctopathy.

Treatment planning and dosimetry of a multi-axis dynamic arc technique for prostate cancer: A comparison with IMRT

PURPOSE

Intensity-modulated radiation therapy (IMRT) allows greater dose conformity to the tumor target. However, IMRT, especially static delivery, usually requires more time to deliver a dose fraction than conventional external beam radiotherapy (EBRT). The authors have been using a "two-axis dynamic arc therapy" (2A-DAT) technique for prostate cancer treatment to make a concave dose distribution to spare the rectum and bladder while working with limited time and human resources. The objectives of this study were to (1) clinically implement the 2A-DAT technique, (2) evaluate the dosimetry in comparison with IMRT, and (3) analyze the initial treatment outcome.

MATERIALS AND METHODS

The 2A-DAT consists of two dynamic arc therapies (DATs) with half rotation around two isocenters each in two separate symmetrical rhombi. Treatment planning is forward and on a trial-and-error basis. Thirty-four patients received 2A-DAT with a median prescribed dose of 70 Gy.

RESULTS

Although inferior in dose uniformity, the 2A-DAT provided equivalent sparing of normal structures to IMRT. Daily fraction delivery time for the 34 patients ranged from 6.4 to 9.6 minutes, with an average of 7.4 minutes. Five-year survival and five-year prostate specific autigen (PSA) failure-free survival were 89.3% and 79.5%, respectively. Three patients developed grade 2 proctitis.

CONCLUSION

This technique is a possible alternative to IMRT in EBRT of prostate cancer.