Lipiodol as a Fiducial Marker for Image-Guided Radiation Therapy for Bladder Cancer

Purpose To evaluate Lipiodol as a liquid, radio-opaque fiducial marker for image-guided radiation therapy (IGRT) for bladder cancer.Materials and Methods Between 2011 and 2012, 5 clinical T2a-T3b N0 M0 stage II-III bladder cancer patients were treated with maximal transurethral resection of a bladder tumor (TURBT) and image-guided radiation therapy (IGRT) to 64.8 Gy in 36 fractions ± concurrent weekly cisplatin-based or gemcitabine chemotherapy. Ten to 15mL Lipiodol, using 0.5mL per injection, was injected into bladder submucosa circumferentially around the entire periphery of the tumor bed immediately following maximal TURBT. The authors looked at inter-observer variability regarding the size and location of the tumor bed (CTVboost) on computed tomography scans with versus without Lipiodol.Results Median follow-up was 18 months. Lipiodol was visible on every orthogonal two-dimensional kV portal image throughout the entire, 7-week course of IGRT. There was a trend towards improved inter-observer agreement on the CTVboost with Lipiodol (p = 0.06). In 2 of 5 patients, the tumor bed based upon Lipiodol extended outside a planning target volume that would have been treated with a radiation boost based upon a cystoscopy report and an enhanced computed tomography (CT) scan for staging. There was no toxicity attributable to Lipiodol.Conclusions Lipiodol constitutes a safe and effective fiducial marker that an urologist can use to demarcate a tumor bed immediately following maximal TURBT. Lipiodol decreases inter-observer variability in the definition of the extent and location of a tumor bed on a treatment planning CT scan for a radiation boost

Outcomes of adjuvant radiotherapy and lymph node dissection in elderly patients with pancreatic cancer treated with surgery and chemotherapy.

Abstract only 332 Background: To determine the effects of postoperative radiation therapy (PORT) and lymph node resection (LNR) on survival in patients age ≥ 70 with pancreatic cancer treated with surgery and chemotherapy. Methods: An analysis of patients with surgically resected pancreatic cancer who received chemotherapy from the SEER database from 2004-2008 was performed to determine association of PORT and LNR on survival. Survival curves were calculated according to the Kaplan-Meier method and log-rank analysis. Multivariate analysis (MVA) was performed by the Cox proportional hazard model. Results: We identified 961 patients who met inclusion criteria. The only significant difference between PORT patients and no PORT patients was age, median 75 and 76 years, respectively (p=0.007). Overall survival (OS) in PORT versus no PORT was not statistically different in the whole cohort (p=0.064), N0 (p=0.803) or N1 (p=0.0501). On univariate analysis (UVA) there was increased OS in patients with lower T stage (p<0.001), N0 status (p<0.001), lower AJCC stage (p<0.001) and lower grade (p<0.001). No OS difference was seen based on gender, location, or PORT. There was no difference in OS based on number of lymph nodes removed in all patients (p=0.74), N0 (p=0.59), and N1 (p=0.07). MVA for all patients revealed higher T stage, N1, and high grade were prognostic for worse mortality, while there was a trend for decreased mortality with PORT (p=0.052). In N0 patients, increased T-stage and grade were prognostic for worse survival, while PORT and number of lymph nodes removed were not. In N1 patients, higher T-stage and grade were prognostic for increased mortality, while increasing number of lymph nodes removed was associated with decreased mortality. PORT trended towards improved survival in N1 patients (p=0.06). Age, gender and tumor location were not prognostic for survival. Conclusions: Adjuvant radiation therapy and number of lymph nodes removed in patients age ≥70 does not seem to correlate with increased OS in surgically resected pancreatic cancer treated with chemotherapy. Future clinical trials will need to address age as a stratification factor for pancreatic cancer in the adjuvant setting

Stereotactic Body Radiation Therapy for Locally Advanced and Borderline Resectable Pancreatic Cancer Is Effective and Well Tolerated

Purpose: Stereotactic body radiation therapy (SBRT) provides high rates of local control (LC) and margin-negative (R0) resections for locally advanced pancreatic cancer (LAPC) and borderline resectable pancreatic cancer (BRPC), respectively, with minimal toxicity. Methods and Materials: A single-institution retrospective review was performed for patients with nonmetastatic pancreatic cancer treated with induction chemotherapy followed by SBRT. SBRT was delivered over 5 consecutive fractions using a dose painting technique including 7-10 Gy/fraction to the region of vessel abutment or encasement and 5-6 Gy/fraction to the remainder of the tumor. Restaging scans were performed at 4 weeks, and resectable patients were considered for resection. The primary endpoints were overall survival (OS) and progression-free survival (PFS). Results: Seventy-three patients were evaluated, with a median follow-up time of 10.5 months. Median doses of 35 Gy and 25 Gy were delivered to the region of vessel involvement and the remainder of the tumor, respectively. Thirty-two BRPC patients (56.1%) underwent surgery, with 31 undergoing an R0 resection (96.9%). The median OS, 1-year OS, median PFS, and 1-year PFS for BRPC versus LAPC patients was 16.4 months versus 15 months, 72.2% versus 68.1%, 9.7 versus 9.8 months, and 42.8% versus 41%, respectively (all P>.10). BRPC patients who underwent R0 resection had improved median OS (19.3 vs 12.3 months; P = .03), 1-year OS (84.2% vs 58.3%; P = .03), and 1-year PFS (56.5% vs 25.0%; P= 3 toxicity, and late grade >= 3 toxicity was minimal (5.3%). Conclusions: SBRT safely facilitates margin-negative resection in patients with BRPC pancreatic cancer while maintaining a high rate of LC in unresectable patients. These data support the expanded implementation of SBRT for pancreatic cancer. (C) 2013 Elsevier Inc

When to add a new process to a model – and when not: A marine biogeochemical perspective

Models are critical tools for environmental science. They allow us to examine the limits of what we think we know and to project that knowledge into situations for which we have little or no data. They are by definition simplifications of reality. There are therefore inevitably times when it is necessary to consider adding a new process to a model that was previously omitted. Doing so may have consequences. It can increase model complexity, affect the time a model takes to run, impact the match between the model output and observations, and complicate comparison to previous studies using the model. How a decision is made on whether to add a process is no more objective than how a scientist might design a laboratory experiment. To illustrate this, we report on an event where a broad and diverse group of marine biogeochemists were invited to construct flowcharts to support making the decision of when to include a new process in a model. The flowcharts are used to illustrate both the complexity of factors that modellers must consider prior to making a decision on model development and the diversity of perspectives on how that decision should be reached. The purpose of this paper is not to provide a definitive protocol for making that decision. Instead, we argue that it is important to acknowledge that there is no objectively “best” approach and instead we discuss the flowcharts created as a means of encouraging modellers to think through why and how they are doing something. This may also hopefully guide observational scientists to understand why it may not always be appropriate to include a process they are studying in a model