Duration of Androgen Deprivation Therapy in High-risk Prostate Cancer: A Randomized Phase III Trial.

BACKGROUND: Long-term androgen deprivation therapy (ADT) combined with radiotherapy (RT) is a standard treatment for patients with localized high-risk prostate cancer (HRPC). However, the optimal duration of ADT is not yet defined. OBJECTIVE: The aim of this superiority randomized trial was to compare outcomes of RT combined with either 36 or 18 mo of ADT. DESIGN, SETTING AND PARTICIPANTS: From October 2000 to January 2008, 630 patients with HRPC were randomized, 310 to pelvic and prostate RT combined with 36 mo (long arm) and 320 to the same RT with 18 mo (short arm) of ADT. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Overall survival (OS) and quality of life (QoL) were primary end points. OS rates were compared with Cox Regression model and QoL data were analyzed through mixed linear model. RESULTS AND LIMITATIONS: With a median follow-up of 9.4 yr, 290 patients had died (147 long arm vs 143 short arm). The 5-yr OS rates (95% confidence interval) were 91% for long arm (88-95%) and 86% for short arm (83-90%), p=0.07. QoL analysis showed a significant difference (p<0.001) in six scales and 13 items favoring 18 mo ADT with two of them presenting a clinically relevant difference in mean scores of ≥10 points. CONCLUSIONS: In localized HRPC, our results support that 36 mo is not superior to 18 mo of ADT. ADT combined with RT can potentially be reduced to 18 mo in selected men without compromising survival or QoL. Thus, 18 mo of ADT appears to represent a valid option in HRPC. PATIENT SUMMARY: In this study, we report outcomes from high-risk prostate cancer patients treated with radiotherapy and either 36 or 18 mo of androgen deprivation therapy. There was no difference in survival between the two groups, with the 18-mo group experiencing a better quality of life.

Partial kilovoltage cone beam computed tomography, complete kilovoltage cone beam computed tomography, and electronic portal images for breast radiation therapy: A dose-comparison study.

PURPOSE: The purpose of this study was to compare absorbed dose with the treated breast and organs at risks (OARs) with weekly image guidance using electronic portal imaging (EPI), complete kilovoltage cone beam computed tomography (kV CBCT), and partial kV CBCT. METHODS AND MATERIALS: Using a thorax female phantom, we determined absorbed doses to treated and contralateral breast, ipsilateral and contralateral lung, heart, and skin for tangential EPI, complete kV CBCT, and partial kV CBCT. Doses were measured by use of ionization chambers and compared with treatment planning system calculations. With simulation of breast tangential irradiation to a standard dose of 50 Gy in 25 fractions, dose to each organ was measured for each image guidance technique. RESULTS: Use of weekly EPI was associated with a significantly increased dose to the treated breast compared with weekly complete and partial kV CBCT (4.44 ± 0.04 vs 1.00 ± 0.07 vs 0.576 ± 0.003 cGy, respectively). Dose to the contralateral breast, ipsilateral and contralateral lung, heart, and contralateral skin was lower with EPI than with either complete or partial kV CBCT (0.042 ± 0.004 vs 0.36 ± 0.01 vs 0.23 ± 0.01 cGy, 0.06 ± 0.04 vs 0.42 ± 0.02 vs 0.31 ± 0.01 cGy, 0.004 ± 0.002 vs 0.29 ± 0.01 vs 0.22 ± 0.01 cGy, 0.03 ± 0.08 vs 0.36 ± 0.02 vs 0.25 ± 0.01 cGy, and 0.20 ± 0.02 vs 0.80 ± 0.06 vs 0.40 ± 0.03 cGy, respectively). Compared with complete CBCT, the use of partial CBCT allowed dose reductions of 42%, 37%, 27%, 24%, and 28% to the ipsilateral breast, contralateral breast, ipsilateral lung, contralateral lung, and heart, respectively. Additional dose from weekly CBCT was significantly lower than treatment-related scatter dose for all OARs. CONCLUSIONS: Use of CBCT was associated with decreased dose to ipsilateral breast and increased dose to all OARs compared with EPI. Significant dose reduction can be achieved with the use of partial CBCT, while generally maintaining image quality.

Multiple ionic-plasmon resonances in naturally occurring multiwall nanotubes: infrared spectra of chrysotile asbestos.

Chrysotile asbestos is formed by densely packed bundles of multiwall hollow nanotubes. Each wall in the nanotubes is a cylindrically wrapped layer of Mg(3)Si(2)O(5)(OH)(4). We show by experiment and theory that the infrared spectra of chrysotile present multiple ionic-plasmon resonances in the Si-O stretching bands. These collective charge excitations are universal features of the nanotubes that are obtained by cylindrically wrapping an anisotropic material. The multiple plasmons can be observed if the width of the resonances is sufficiently small as in chrysotile.