Distinct effects of rectum delineation methods in 3D-confromal vs. IMRT treatment planning of prostate cancer

BACKGROUND: The dose distribution to the rectum, delineated as solid organ, rectal wall and rectal surface, in 3D conformal (3D-CRT) and intensity-modulated radiotherapy treatment (IMRT) planning for localized prostate cancer was evaluated. MATERIALS AND METHODS: In a retrospective planning study 3-field, 4-field and IMRT treatment plans were analyzed for ten patients with localized prostate cancer. The dose to the rectum was evaluated based on dose-volume histograms of 1) the entire rectal volume (DVH) 2) manually delineated rectal wall (DWH) 3) rectal wall with 3 mm wall thickness (DWH(3)) 4) and the rectal surface (DSH). The influence of the rectal filling and of the seminal vesicles' anatomy on these dose parameters was investigated. A literature review of the dose-volume relationship for late rectal toxicity was conducted. RESULTS: In 3D-CRT (3-field and 4-field) the dose parameters differed most in the mid-dose region: the DWH showed significantly lower doses to the rectum (8.7% ± 4.2%) compared to the DWH(3 )and the DSH. In IMRT the differences between dose parameters were larger in comparison with 3D-CRT. Differences were statistically significant between DVH and all other dose parameters and between DWH and DSH. Mean doses were increased by 23.6% ± 8.7% in the DSH compared to the DVH in the mid-dose region. Furthermore, both the rectal filling and the anatomy of the seminal vesicles influenced the relationship between the dose parameters: a significant correlation of the difference between DVH and DWH and the rectal volume was seen in IMRT treatment. DISCUSSION: The method of delineating the rectum significantly influenced the dose representation in the dose-volume histogram. This effect was pronounced in IMRT treatment planning compared to 3D-CRT. For integration of dose-volume parameters from the literature into clinical practice these results have to be considered

Does Intensity Modulated Radiation Therapy (IMRT) prevent additional toxicity of treating the pelvic lymph nodes compared to treatment of the prostate only?

<p>Abstract</p> <p>Background</p> <p>To evaluate the risk of rectal, bladder and small bowel toxicity in intensity modulated radiation therapy (IMRT) of the prostate only compared to additional irradiation of the pelvic lymphatic region.</p> <p>Methods</p> <p>For ten patients with localized prostate cancer, IMRT plans with a simultaneous integrated boost (SIB) were generated for treatment of the prostate only (plan-PO) and for additional treatment of the pelvic lymph nodes (plan-WP). In plan-PO, doses of 60 Gy and 74 Gy (33 fractions) were prescribed to the seminal vesicles and to the prostate, respectively. Three plans-WP were generated with prescription doses of 46 Gy, 50.4 Gy and 54 Gy to the pelvic target volume; doses to the prostate and seminal vesicles were identical to plan-PO. The risk of rectal, bladder and small bowel toxicity was estimated based on NTCP calculations.</p> <p>Results</p> <p>Doses to the prostate were not significantly different between plan-PO and plan-WP and doses to the pelvic lymph nodes were as planned. Plan-WP resulted in increased doses to the rectum in the low-dose region ≤ 30 Gy, only, no difference was observed in the mid and high-dose region. Normal tissue complication probability (NTCP) for late rectal toxicity ranged between 5% and 8% with no significant difference between plan-PO and plan-WP. NTCP for late bladder toxicity was less than 1% for both plan-PO and plan-WP. The risk of small bowel toxicity was moderately increased for plan-WP.</p> <p>Discussion</p> <p>This retrospective planning study predicted similar risks of rectal, bladder and small bowel toxicity for IMRT treatment of the prostate only and for additional treatment of the pelvic lymph nodes.</p

The morbidity of treatment for patients with stage I endometrial cancer:Results from a randomized trial

Purpose: To compare the treatment complications for patients with Stage I endometrial cancer treated with surgery and pelvic radiotherapy (RT) or surgery alone in a multicenter randomized trial. Methods and Materials: The Postoperative Radiation Therapy in Endometrial Carcinoma (PORTEC) trial included patients with endometrial cancer confined to the uterine corpus, either Grade 1 or 2 with more than 50% myometrial invasion, or Grade 2 or 3 with less than 50% myometrial invasion. Surgery consisted of an abdominal hysterectomy and oophorectomy, without lymphadenectomy. After surgery, patients were randomized to receive pelvic RT (46 Gy), or no further treatment. A total of 715 patients were randomized. Treatment complications were graded using the French-Italian glossary. Results: The analysis was done at a median follow-up duration of 60 months. 691 patients were evaluable. Five-year actuarial rates of late complications (Grades 1-4) were 26% in the RT group and 4% in the control group (p <0.0001). Most were Grade 1 complications, with 5-year rates of 17% in the RT group and 4% in the control group. All severe (Grade 3-4) complications were observed in the RT group (3%). Most complications were of the gastrointestinal tract. The symptoms resolved after some years in 50% of the patients. Grade 1-2 genitourinary complications occurred in 8% of the RT patients, and 4% of the controls. Bone complications occurred in 4 RT patients (1%). Seven patients (2%) discontinued their RT due to acute RT-related symptoms. Patients with acute morbidity had an increased risk of late RT complications (p = 0.001). The 4-field box technique was associated with a lower risk of late complications (p = 0.06). Conclusion: Pelvic RT increases the morbidity of treatment in Stage I endometrial cancer. In the PORTEC trial, severe complications occurred in 3% of treated patients, and over 20% experienced mild (mostly Grade 1) symptoms. Patients with acute RT-related morbidity had an increased risk of late complications. As pelvic RT in Stage I endometrial carcinoma was shown to significantly reduce the rate of locoregional recurrence, but without a survival benefit, its use in the adjuvant setting requires careful patient selection (treating those at increased risk of relapse), and the use of treatment schemes with the lowest risk of morbidity. (C) 2001 Elsevier Science Inc

Survival after relapse in patients with endometrial cancer:results from a randomized trial

Objective. The aim of this study was to determine the rates of local control and survival after relapse in patients with stage I endometrial cancer treated in the multicenter randomized PORTEC trial. Methods, The PORTEC trial included 715 patients with stage I endometrial cancer, either grade I or 2 with deep (>50%) myometrial invasion or grade 2 or 3 with Results. The analysis was done by intention-to-treat. A total of 714 patients were evaluated. At a median follow-up of 73 months, 8-year actuarial locoregional recurrence rates were 4% in the RT group and 15% in the control group (P <0.0001). The 8-year actuarial overall survival rates were 71 (RT group) and 77% (control group, P = 0.18). Eight-year rates of distant metastases were 10 and 6% (P = 0.20). The majority of the locoregional relapses were located in the vagina, mainly in the vaginal vault. Of the 39 patients with isolated vaginal relapse, 35 (87%) were treated with curative intent, usually with external RT and brachytherapy, and surgery in some. A complete remission (CR) was obtained in 31 of the 35 patients (89%), and 24 patients (77%) were still in CR after further follow-up. Five patients subsequently developed distant metastases, and 2 had a second vaginal recurrence. The 3-year survival after first relapse was 51% for patients in the control group and 19% in the RT group (P = 0.004). The 3-year survival after vaginal relapse was 73%, in contrast to 8 and 14% after pelvic and distant relapse (P <0.001). At 5 years, the survival after vaginal relapse was 65% in the control group compared to 43% in the RT group. Conclusion. Survival after relapse was significantly better in the patient group without previous RT. Treatment for vaginal relapse was effective, with 89% CR and 65% 5-year survival in the control group, while there was no difference in survival between patients with pelvic relapse and those with distant metastases. As pelvic RT was shown to improve locoregional control significantly, but without a survival benefit, its use should be limited to those patients at sufficiently high risk (15% or over) for recurrence in order to maximize local control and relapse-free survival. (C) 2003 Elsevier Science (USA). All rights reserved