Huong T. Pham

Intrafractional stability of the prostate using a stereotactic radiotherapy technique

Abstract Purpose To evaluate the stability of the prostate during stereotactic radiation therapy. Methods and materials Forty-seven patients underwent placement of three fiducial markers into the prostate as part of a pilot study of hypofractionated stereotactic radiotherapy. Portal images before and subsequent to 227 radiotherapy fractions were analyzed for prostate movement. Six patients also underwent localizing radiographs at 6-min intervals for 24 min. Relative motion of the bony landmarks and prostate markers was calculated. Results Analysis of portal images revealed the undirected average prostate movement of 2.0 mm (superior/inferior), 1.9 mm (anterior/posterior), and 1.4 mm (right/left) with maximum standard deviation (SD) of 2.0. Analysis of radiographs at 6-min intervals showed the greatest undirected average prostate motion between 0–6 min; 1.5 mm (superior/inferior), 1.4 mm (anterior/posterior), and 0.4 mm (right/left). Beyond 6 min, movements decreased to 0.4, 0.9, and 0.8 mm, respectively. Bony landmark motion was 0.9 mm (superior/inferior), 0.9 mm (anterior/posterior), and 0.4 mm (right/left) between 0–6 min. Beyond 6 min, motion decreased to less than 0.5 mm in any direction. Conclusions Stereotactic prostate radiotherapy, utilizing fiducial marker localization, resulted in average intrafractional prostate movement of 2.0 mm or less. Most patient and organ movement occurs early and a settling-in period is advisable before treatment.

Phase II Study of Long-Term Androgen Suppression With Bevacizumab and Intensity-Modulated Radiation Therapy (IMRT) in High-Risk Prostate Cancer

PURPOSE We report a Phase II trial assessing the acute and late toxicities of intensity-modulated radiation therapy (IMRT), long-term androgen suppression (LTAS), and bevacizumab in patients with high-risk localized prostate cancer. METHODS AND MATERIALS We treated 18 patients with LTAS with bicalutamide and goserelin in combination with bevacizumab and IMRT. Bevacizumab (10 mg/kg every 2 weeks) was administered for the first 16 weeks, and 15 mg/kg was then given every 3 weeks for 12 additional weeks, with an IMRT dose of 77.9 Gy to the prostate, 64.6 Gy to the seminal vesicles, and 57 Gy to the pelvic lymph nodes. Patients were eligible if they had clinical stage T2b to T4, a Gleason sum score of 8 to 10, or a prostate- specific antigen level of 20ng/mL or greater. The primary endpoint of the study was evaluation of acute and late toxicities. RESULTS The median age was 69 years, with a median pretreatment prostate-specific antigen level of 12.5 ng/mL and Gleason score of 8. The pretreatment clinical stage was T1c in 4 patients, T2 in 11, and T3 in 3. All patients completed IMRT with median follow-up of 34 months (range, 28-40 months) The most common Grade 2 or higher toxicities were hypertension (61% of patients with Grade 2 and 11% with Grade 3), proteinuria (28% with Grade 2 and 6% with Grade 3), and leucopenia (28% with Grade 2). No Grade 4 or higher acute toxicities were reported. Late toxicities included proctitis (6% of patients with Grade 2 and 11% with Grade 3), rectal bleeding (6% with Grade 2 and 11% with Grade 3), hematuria (6% with Grade 2), proteinuria (17% with Grade 2), hyponatremia (6% with Grade 3), cystitis (6% with Grade 3), and urinary retention (6% with Grade 2 and 11% with Grade 3). Grade 4 prostatitis occurred in 1 patient (6%). CONCLUSIONS Bevacizumab does not appear to exacerbate the acute effects of IMRT. Late toxicities may have been worsened with this regimen. Further investigations of bevacizumab with LTAS and IMRT should be performed cautiously.

Permanent prostate brachytherapy using high V150

PURPOSE Prostate brachytherapy sometimes requires the volume receiving >150% of the prescribed dose (V150) to be >50% to obtain satisfactory coverage. There has been concern expressed that high V150 may be associated with higher rates of urinary retention and morbidity. METHODS AND MATERIALS We reviewed 207 consecutive cases of prostate brachytherapy treated with palladium 103 ((103)Pd; n = 140) or iodine 125 ((125)I; n = 67). Prescribed doses for (103)Pd monotherapy and boost were 124 and 90 Gy, respectively; for (125)I, the corresponding doses were 160 and 120 Gy. Patients were evaluated at baseline, 1 month, 3 months, and every 6 months thereafter. RESULTS Median follow-up at the time of analysis was 18 months. For (103)Pd, the mean intraoperative volume and V150 were 30.3 cm(3) and 72%, respectively; corresponding values for (125)I were 38.3 cm(3) and 59%, respectively. Two of the patients treated with iodine and 9 treated with palladium experienced acute urinary retention, which was not statistically significant (P = .48). The rectal V100 for (103)Pd was significantly less than that for (125)I (P < .001). The mean baseline, 1-month, and 12-month American Urologic Association (AUA) scores for (103)Pd were 8.5, 19.7, and 8.2, respectively; for (125)I, the values were 7.4, 17.1, and 13.4, respectively. At 12 months, the AUA scores returned to baseline in the (103)Pd-treated patients, whereas scores in (125)I-treated patients remained elevated (P = .005). High V150 did not appear to cause undue risk of urinary retention or morbidity based on logistic regression analysis of patients treated with monotherapy performed with either isotope. CONCLUSIONS The risk of urinary retention was low, despite high V150 values for both isotopes. In patients treated with brachytherapy alone, no significant increase in urinary morbidity was seen in relation to V150. AUA scores returned to baseline in (103)Pd-treated patients at 1 year, whereas (125)I-treated patients demonstrated continued elevation.

Intrafractional Stability of the Prostate Using a Stereotactic Radiotherapy Technique: 10:43 AM (31)

PURPOSE To evaluate the stability of the prostate during stereotactic radiation therapy. MATERIALS AND METHODS Forty-seven patients underwent placement of three fiducial markers into the prostate as part of a pilot study of hypofractionated stereotactic radiotherapy. Portal images before and subsequent to 227 radiotherapy fractions were analyzed for prostate movement. Six patients also underwent localizing radiographs at 6-min intervals for 24 min. Relative motion of the bony landmarks and prostate markers was calculated. RESULTS Analysis of portal images revealed the undirected average prostate movement of 2.0 mm (superior/inferior), 1.9 mm (anterior/posterior), and 1.4 mm (right/left) with maximum standard deviation (SD) of 2.0. Analysis of radiographs at 6-min intervals showed the greatest undirected average prostate motion between 0-6 min; 1.5 mm (superior/inferior), 1.4 mm (anterior/posterior), and 0.4 mm (right/left). Beyond 6 min, movements decreased to 0.4, 0.9, and 0.8 mm, respectively. Bony landmark motion was 0.9 mm (superior/inferior), 0.9 mm (anterior/posterior), and 0.4 mm (right/left) between 0-6 min. Beyond 6 min, motion decreased to less than 0.5 mm in any direction. CONCLUSIONS Stereotactic prostate radiotherapy, utilizing fiducial marker localization, resulted in average intrafractional prostate movement of 2.0 mm or less. Most patient and organ movement occurs early and a settling-in period is advisable before treatment.