Treatment outcome of high-dose image-guided intensity-modulated radiotherapy using intra-prostate fiducial markers for localized prostate cancer at a single institute in Japan.

BACKGROUND: Several studies have confirmed the advantages of delivering high doses of external beam radiotherapy to achieve optimal tumor-control outcomes in patients with localized prostate cancer. We evaluated the medium-term treatment outcome after high-dose, image-guided intensity-modulated radiotherapy (IMRT) using intra-prostate fiducial markers for clinically localized prostate cancer. METHODS: In total, 141 patients with localized prostate cancer treated with image-guided IMRT (76 Gy in 13 patients and 80 Gy in 128 patients) between 2003 and 2008 were enrolled in this study. The patients were classified according to the National Comprehensive Cancer Network-defined risk groups. Thirty-six intermediate-risk patients and 105 high-risk patients were included. Androgen-deprivation therapy was performed in 124 patients (88%) for a median of 11 months (range: 2-88 months). Prostate-specific antigen (PSA) relapse was defined according to the Phoenix-definition (i.e., an absolute nadir plus 2 ng/ml dated at the call). The 5-year actuarial PSA relapse-free survival, the 5-year distant metastasis-free survival, the 5-year cause-specific survival (CSS), the 5-year overall survival (OS) outcomes and the acute and late toxicities were analyzed. The toxicity data were scored according to the Common Terminology Criteria for Adverse Events, version 4.0. The median follow-up was 60 months. RESULTS: The 5-year PSA relapse-free survival rates were 100% for the intermediate-risk patients and 82.2% for the high-risk patients; the 5-year actuarial distant metastasis-free survival rates were 100% and 95% for the intermediate- and high-risk patients, respectively; the 5-year CSS rates were 100% for both patient subsets; and the 5-year OS rates were 100% and 91.7% for the intermediate- and high-risk patients, respectively. The Gleason score (<8 vs. ≥ 8) was significant for the 5-year PSA relapse-free survival on multivariate analysis (p = 0.044). There was no grade 3 or 4 acute toxicity. The incidence of grade 2 acute gastrointestinal (GI) and genitourinary (GU) toxicities were 1.4% and 8.5%, respectively. The 5-year actuarial likelihood of late grade 2-3 GI and GU toxicities were 6% and 6.3%, respectively. No grade 4 GI or GU late toxicity was observed. CONCLUSIONS: These medium-term results demonstrate a good tolerance of high-dose image-guided IMRT. However, further follow-up is needed to confirm the long-term treatment outcomes.

Focal dose escalation using FDG-PET-guided intensity-modulated radiation therapy boost for postoperative local recurrent rectal cancer: a planning study with comparison of DVH and NTCP.

BACKGROUND: To evaluate the safety of focal dose escalation to regions with standardized uptake value (SUV) >2.0 using intensity-modulated radiation therapy (IMRT) by comparison of radiotherapy plans using dose-volume histograms (DVHs) and normal tissue complication probability (NTCP) for postoperative local recurrent rectal cancer METHODS: First, we performed conventional radiotherapy with 40 Gy/20 fr. (CRT 40 Gy) for 12 patients with postoperative local recurrent rectal cancer, and then we performed FDG-PET/CT radiotherapy planning for those patients. We defined the regions with SUV > 2.0 as biological target volume (BTV) and made three boost plans for each patient: 1) CRT boost plan, 2) IMRT without dose-painting boost plan, and 3) IMRT with dose-painting boost plan. The total boost dose was 20 Gy. In IMRT with dose-painting boost plan, we increased the dose for BTV+5 mm by 30% of the prescribed dose. We added CRT boost plan to CRT 40 Gy (summed plan 1), IMRT without dose-painting boost plan to CRT 40 Gy (summed plan 2) and IMRT with dose-painting boost plan to CRT 40 Gy (summed plan 3), and we compared those plans using DVHs and NTCP. RESULTS: D(mean) of PTV-PET and that of PTV-CT were 26.5 Gy and 21.3 Gy, respectively. V50 of small bowel PRV in summed plan 1 was significantly higher than those in other plans ((summed plan 1 vs. summed plan 2 vs. summed plan 3: 47.11 +/- 45.33 cm3 vs. 40.63 +/- 39.13 cm3 vs. 41.25 +/- 39.96 cm3 (p < 0.01, respectively)). There were no significant differences in V30, V40, V60, D(mean) or NTCP of small bowel PRV. CONCLUSIONS: FDG-PET-guided IMRT can facilitate focal dose-escalation to regions with SUV above 2.0 for postoperative local recurrent rectal cancer.

Clinical correlations between treatment with anticoagulants/antiaggregants and late rectal toxicity after radiotherapy for prostate cancer.

AIM: To assess variables related to grade 2 or higher late rectal toxicity (LRT) in prostate cancer treated with external radiotherapy. PATIENTS AND METHODS: A retrospective analysis was carried out of 232 patients with T1-T3 prostate cancer treated with 3-dimensional conformal radiotherapy (3DCRT) (106 patients) or intensity modulated radiotherapy (IMRT) (126 patients) between June 2000 and May 2007. One hundred and seventy-seven patients received androgen deprivation therapy (ADT); fifty patients used anticoagulants/antiaggregants for vascular disease. RESULTS: The median follow-up was 31 months (range, 6-79). At 5 years, the cumulative incidence of grade 2 or 3 LRT was 5.6% . On multivariate analysis, medication with anticoagulants/antiaggregants was correlated with grade 2 or 3 LRT (p=0.027), whereas age, National Comprehensive Cancer Network risk group classification, use of ADT, radiotherapy technique (3DCRT vs. IMRT) and total irradiated dose were not. CONCLUSION: Treatment with anticoagulants/antiaggregants appears to be a factor in grade 2 or 3 LRT.

A phase II study on stereotactic body radiotherapy for stage I non-small cell lung cancer.

BACKGROUND AND PURPOSE: The outcome of stage I non-small cell lung cancer (NSCLC) patients treated with conventional radiotherapy is inferior to that of patients treated surgically. We aimed to evaluate the clinical outcome of stereotactic body radiotherapy (SBRT) in the treatment of stage I NSCLC. MATERIALS AND METHODS: We performed SBRT for 31 stage I NSCLC patients. Of these, 20 were medically inoperable, and 11 refused surgery. Nineteen tumours were T1-stage masses, and 12 tumours were T2. Median tumour size was 25 mm. SBRT was administered as 45 Gy/3 fractions; however, when the tumour was close to an organ at risk, 60 Gy/8 fractions were used. These doses were prescribed at the centre of the tumours. RESULTS: The median duration of observation for all patients was 32 months (range, 4-87 months). In 9 of the 31 cases, local recurrence was observed. The 3-year local control rates of T1 and T2 tumours were 77.9% and 40.0%, respectively. The 3-year overall and cause-specific survival rates were 71.7% and 83.5%, respectively. Although the symptoms improved with medical treatment, 5 patients developed acute pulmonary toxicity > or =grade 2. CONCLUSIONS: SBRT is safe and effective for stage I NSCLC patients. However, a more intensive treatment regimen should be considered for T2 tumours.

Evaluation of inter- and intrafraction organ motion during intensity modulated radiation therapy (IMRT) for localized prostate cancer measured by a newly developed on-board image-guided system.

PURPOSE: To investigate prostatic organ motion at both setup and intrafraction using an onboard image-guided system. An intrafraction field-based repositioning method also was evaluated. MATERIALS AND METHODS: A dual fluoroscopy with amorphous-silicon flat panel (DFFP) system was used for the three-dimensional registration of implanted markers in the prostate of eight organ-confined cancer patients planned for treatment with intensity modulated radiation therapy (IMRT). Day-to-day motion errors were quantified and intrafraction displacements of more than +/-1 mm were corrected. RESULTS: Among 214 fractions and 565 system views, day-to-day mean magnitude of marker discrepancy +/- standard deviation (SD) was 1.76 +/- 1.4 mm, 3.14 +/- 1.6 mm, and 3.78 +/- 2.4 mm in the right-left, cranial-caudal, and anterior-posterior directions, respectively. The intrafractional mean magnitude +/- SD of marker displacement was 0.45 +/- 0.7 mm, 1.08 +/- 1.38 mm and 1.45 +/- 1.70 mm in the right-left, cranial-caudal, and anterior-posterior directions, respectively. Intrafraction corrected sessions (84/214) showed a median (range) of motion of 0.1 mm (-1.2 to 0.7 mm), -0.2 mm (-2.1 to 1.1 mm), and -0.2 mm (-1.7 to 2.0 mm) in the right-left, cranial-caudal, and anterior-posterior directions, respectively. CONCLUSION: Motion uncertainty can be considerably decreased with daily use of the DFFP system. Reduced intrafraction organ motion clearly endorsed the value of the repositioning approach, allowing a safer dose escalation protocol.

Stability of electron-beam energy monitor for quality assurance of the electron-beam energy from radiotherapy accelerators.

Information on electron energy is important in planning radiation therapy using electrons. The Geske 3405 electron beam energy monitor (Geske monitor, PTW Nuclear Associates, Carle Place, NY, USA) is a device containing nine ionization chambers for checking the energy of the electron beams produced by radiotherapy accelerators. We wondered whether this might increase the likelihood of ionization chamber trouble. In spite of the importance of the stability of such a quality assurance (QA) device, there are no reports on the stability of values measured with a Geske monitor. The purpose of this paper was therefore to describe the stability of a Geske monitor. It was found that the largest coefficient of variation (CV) of the Geske monitor measurements was approximately 0.96% over a 21-week period. In conclusion, the stability of Geske monitor measurements of the energy of electron beams from a linear accelerator was excellent.