Brachytherapy boost for prostate cancer: Trends in care and survival outcomes.

PURPOSE: Androgen suppression combined with elective nodal and dose-escalated radiation therapy recently demonstrated an improved biochemical failure-free survival in men who received external beam radiation therapy (EBRT) plus a brachytherapy boost (BB) compared with dose-escalated external beam radiotherapy (DE-EBRT). We sought to analyze the factors predictive for use of EBRT + BB as compared with DE-EBRT and report resulting survival outcomes on a national level using a hospital-based registry. METHODS AND MATERIALS: We identified 113,719 men from the National Cancer Database from 2004 to 2013 with intermediate- or high-risk prostate cancer who were treated with EBRT + BB or DE-EBRT. We performed univariate and multivariate analyses of all available factors potentially predictive of receipt of treatment selection. Survival was evaluated in a multivariable model with propensity adjustment. RESULTS: For intermediate-risk patients, utilization of BB decreased from 33.1% (n = 1742) in 2004 to 12.5% (n = 766) in 2013 and for high-risk patients, utilization dropped from 27.6% (n = 879) to 10.8% (n = 479). Numerous factors predictive for use of BB were identified. Cox proportional hazards analysis was performed-adjusting for age, Charlson-Deyo comorbidity score, T stage, prostate-specific antigen, Gleason score, and sociodemographic factors-and demonstrated BB use was associated with a hazard ratio of 0.71 (95% confidence interval, 0.67-0.75; p < 0.0005) and 0.73 (95% confidence interval, 0.68-0.78; p < 0.0005) for intermediate- and high-risk patients, respectively. CONCLUSIONS: There has been a concerning decline in the utilization of BB for intermediate- and high-risk prostate cancer patients despite an association with improved on overall survival. Numerous factors predictive for use of BB have been identified.

SU-E-T-07: Edema Induced Changes in Tumor Cell Survival Fraction and Tumor Control Probability in 131Cs Permanent Prostate Implant Patients.

PURPOSE: The purpose of this study is to estimate the effect of edema, developed during implant procedure, on tumor cell surviving fraction(SF) and tumor control probability(TCP) in the patients of prostate cancer who underwent 131 Cs permanent seed implants. METHODS: The impact of edema on SF and TCP, was calculated using LQ equation extended to account for exponential nature of edema decay, dose delivered to dematous prostate and inhomogeneous dose distribution. Where (1) S(D)=(1/V)Σi=1n [Vpi{1+M0 exp(-λe t)}Si (D)] Si (D)=exp[-αRi (0)∫0t [exp(- λt)/{1+M0 exp(-λe t)}τ/3]dt -ßq(t){Ri (0)∫0t [exp(-λt)/{1+M0 exp(-λe t)}τ/3]dt }2 ] and (2) TCP=exp[-ρVpS(D)] Following parameters, α=0.15Gy-1 , ß=0.05Gy-2 , α/ß=3.0Gy, Tp=42days, µ=61.6d-1 and ρ=1×106 are used to calculate SF and TCP for 31 patients of 131 Cs permanent seed implants for edema half lives(EHL) ranging from 4 days to 34 days and for edemas of magnitudes(M0 ) varying from 5% to 60% of the actual prostate volume. RESULTS: The dose reductions in 131 Cs implants varied from 1.1% (for EHL=4 days and M0 =5%) to 32.3% (for EHL= 34 days and M0 = 60%). These are higher than the dose reduction in 125 I implants, which vary from 0.3% (for EHL= 4 days and M0 = 5%) to 17.5% (for EHL= 34 days and M0 = 60%). As edema half life increased from 4 days to 34 days and edema magnitude increased from 5% to 60% the SF increased by 4.57 log, and the TCP decreased by 0.80. CONCLUSIONS: Compensation of edema induced increase in the SF and decrease in the TCP in 131 Cs seed implants should be carefully done by redefining seed positions with the guidance of post needle plans. The presented model in this study can be used to estimate the SF or the TCP for pre plan or real time permanent prostate implants using day 0 post implant CT images.

Malaria prophylaxis in travelers.

Each year increasing numbers of Americans travel to countries where the risk of acquiring malaria is considerable. Appropriate advice from family physicians about malaria prophylaxis is important to prevent malaria in American travelers. All travelers to malarious areas should receive chloroquine prophylaxis. Physicians should consider the diagnosis of malaria when fever develops in travelers returning from malarious areas.