J. Shaffer
Stanford University
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Featured researches published by J. Shaffer.
Journal of Clinical Oncology | 2016
Ben Y. Durkee; Yushen Qian; Erqi L. Pollom; Martin T. King; S.A. Dudley; J. Shaffer; Daniel T. Chang; Iris C. Gibbs; Jeremy D. Goldhaber-Fiebert; Kathleen C. Horst
PURPOSE The Clinical Evaluation of Pertuzumab and Trastuzumab (CLEOPATRA) study showed a 15.7-month survival benefit with the addition of pertuzumab to docetaxel and trastuzumab (THP) as first-line treatment for patients with human epidermal growth factor receptor 2 (HER2) -overexpressing metastatic breast cancer. We performed a cost-effectiveness analysis to assess the value of adding pertuzumab. PATIENT AND METHODS We developed a decision-analytic Markov model to evaluate the cost effectiveness of docetaxel plus trastuzumab (TH) with or without pertuzumab in US patients with metastatic breast cancer. The model followed patients weekly over their remaining lifetimes. Health states included stable disease, progressing disease, hospice, and death. Transition probabilities were based on the CLEOPATRA study. Costs reflected the 2014 Medicare rates. Health state utilities were the same as those used in other recent cost-effectiveness studies of trastuzumab and pertuzumab. Outcomes included health benefits expressed as discounted quality-adjusted life-years (QALYs), costs in US dollars, and cost effectiveness expressed as an incremental cost-effectiveness ratio. One- and multiway deterministic and probabilistic sensitivity analyses explored the effects of specific assumptions. RESULTS Modeled median survival was 39.4 months for TH and 56.9 months for THP. The addition of pertuzumab resulted in an additional 1.81 life-years gained, or 0.62 QALYs, at a cost of
Radiotherapy and Oncology | 2017
D.A.S. Toesca; E. Osmundson; Rie von Eyben; J. Shaffer; Peter S. Lu; Albert C. Koong; Daniel T. Chang
472,668 per QALY gained. Deterministic sensitivity analysis showed that THP is unlikely to be cost effective even under the most favorable assumptions, and probabilistic sensitivity analysis predicted 0% chance of cost effectiveness at a willingness to pay of
Practical radiation oncology | 2017
D.A.S. Toesca; E. Osmundson; Rie von Eyben; J. Shaffer; Albert C. Koong; Daniel T. Chang
100,000 per QALY gained. CONCLUSION THP in patients with metastatic HER2-positive breast cancer is unlikely to be cost effective in the United States.
Journal of Clinical Pathology | 2015
Margaret M. Kozak; Rie von Eyben; J. Pai; Stephen R Vossler; Maneesha Limaye; Priya Jayachandran; Eric M. Anderson; J. Shaffer; Teri A. Longacre; Reetesh K. Pai; Albert C. Koong; Daniel T. Chang
PURPOSE To further explore the correlation of central biliary tract (cHBT) radiation doses with hepatobiliary toxicity (HBT) after stereotactic body radiation therapy (SBRT) in a larger patient dataset. METHODS We reviewed the treatment and outcomes of all patients who received SBRT for primary liver cancer (PLC) and metastatic liver tumors between July 2004 and November 2015 at our institution. The cHBT was defined as isotropic expansions (5, 10, 15, 20 and 25mm) from the portal vein (PV). Doses were converted to biologically effective doses by using the standard linear quadratic model with α/β of 10 (BED10). HBT was graded according to the Common Terminology Criteria for Adverse Events v4.03. RESULTS Median follow-up was 13months. Out of the 130 patients with complete follow-up records analyzed, 60 (46.1%) had liver metastases, 40 (30.8%) had hepatocellular carcinoma (HCC), 26 (20%) had cholangiocarcinoma (CCA) and 4 (3.1%) patients other PLC histologies. Thirty-three (25.4%) grade 2+ and 28 (21.5%) grade 3+ HBT were observed. Grade 3+ HBT was seen in 13 patients (50%) with CCA, 7 patients (17.5%) with HCC and 7 (11.7%) patients with liver metastases. SBRT doses to the cHBT were highly associated with HBT, but only for PLC patients when analyzed by histological subtype. The 15mm expansion from the PV (cHBT15) proved to be an appropriate surrogate for the cHBT. The strongest cHBT15 dose predictors for G3+ HBT for PLC were the VBED1040⩾37cc (p<0.0001) and the VBED1030⩾45cc (p<0.0001). CONCLUSION SBRT doses to the cHBT are associated with occurrence of HBT only in PLC patients. Limiting the dose to the cHBT to VBED1040<37cc and VBED1030<45cc when treating PLC patients with SBRT may reduce the risk of HBT.
Practical radiation oncology | 2015
J. Shaffer; E. Osmundson; Brendan C. Visser; Teri A. Longacre; Albert C. Koong; Daniel T. Chang
PURPOSE This study aims to determine how the albumin-bilirubin (ALBI) score compares with the Child-Pugh (CP) score for assessing liver function following stereotactic body radiation therapy (SBRT). METHODS AND MATERIALS In total, 60 patients, 40 with hepatocellular carcinoma (HCC) and 20 with cholangiocarcinoma (CCA), were treated with SBRT. Liver function panels were obtained before and at 1, 3, 6, and 12 months after SBRT. Laboratory values were censored after locoregional recurrence, further liver-directed therapies, or liver transplant. RESULTS A significant decline in hepatic function occurred after SBRT for HCC patients only (P = .001 by ALBI score; P < .0001 by CP score). By converting radiation doses to biologically equivalent doses by using a standard linear quadratic model using α/β of 10, the strongest dosimetric predictor of liver function decline for HCC was the volume of normal liver irradiated by a dose of 40 Gy when assessing liver function by the ALBI score (P = .07), and the volume of normal liver irradiated by a dose of 20 Gy by using the CP score (P= .0009). For CCA patients, the volume of normal liver irradiated by a dose of 40 Gy remained the strongest dosimetric predictor when using the ALBI score (P = .002), but no dosimetric predictor was significant using the CP score. Hepatic function decline correlated with worse overall survival for HCC (by ALBI, P = .0005; by CP, P < .0001) and for CCA (by ALBI, P = NS; by CP, P = .008). CONCLUSIONS ALBI score was similarly able to predict hepatic function decline compared with CP score, and both systems correlated with survival.
Neurosurgery | 2018
J.L. Shah; Gordon Li; J. Shaffer; M. Azoulay; Iris C. Gibbs; Seema Nagpal; Scott G. Soltys
Aims To determine whether expression of Smad4, a tumour suppressor found to be absent in 10% of colorectal cancer (CRC), is associated with outcomes in patients with CRC. Methods Tumour samples from 241 consecutive patients with CRC who underwent upfront colon resection between 2005 and 2009 were obtained. Triplicate tissue cores from resected primary colon tumours and matched normal controls were used to construct the tissue microarrays (TMAs). We examined the expression of Smad4 using immunohistochemistry. Clinicopathological records were obtained for all patients. TMAs were reviewed by two pathologists and scored as either ‘positive’ or ‘negative’ for nuclear staining. In total, 21 of 241 tumours (8.6%) were Smad4 negative. Results Loss of Smad4 expression correlated with significantly worse overall survival (OS) (p=0.011) and disease-free survival (DFS) (p=0.024). Patients with loss of Smad4 expression had a median OS of 31 months compared with 89 months positive Smad4 expression. Loss of Smad4 remained significant on multivariate analysis for OS (p=0.0097). In patients with node-positive disease, loss of Smad4 predicts for worse DFS (p=0.012). In patients with metastatic and recurrent disease, Smad4 loss predicts for worse OS (p=0.012). Of the patients that received capecitabine over the course of their treatment, those with Smad4 loss (n=13) had significantly worse DFS (p=0.003) and OS (p=0.0007). Conclusions Loss of Smad4 expression is associated with worse DFS and OS in multiple subsets of patients with CRC. Further studies are required to validate our findings and ascertain the role of Smad4 status in the management of this disease.
Pancreas | 2014
D.B. Shultz; Cato Chan; J. Shaffer; Pamela L. Kunz; Albert C. Koong; Daniel T. Chang
Stereotactic body radiation therapy (SBRT) has become an increasingly common component in the treatment of primary andmetastatic liver tumors. Liver SBRT allows for focused high-dose radiation to the target while minimizing dose to the remaining liver. In the majority of cases, this treatment is effective and well tolerated; however, some studies have reported up to 30% grade 3 or higher toxicity.1 One of the potential risks of liver SBRT is radiation-induced liver disease (RILD), which is characterized by nonicteric ascites, hepatomegaly, and elevated alkaline phosphatase and typically develops 4 weeks to 3 months after treatment. The risk of RILD can be reduced by minimizing the mean liver dose or by sparing a critical volume of liver from receiving more than the dose tolerance. However, for centrally located liver lesions, RILD does not account for damage specific to the central hepatobiliary tree and portal vein, and the traditional dose constraints do not account for the specific tolerance of these structures. Toxicity of the central hepatobiliary tree may be attributable to stenosis/stricture, which could lead to elevated alkaline phosphatase, jaundice, and cholangitis. To further characterize the potential toxicity of SBRT, we describe a case of a patient who underwent liver
International Journal of Radiation Oncology Biology Physics | 2013
Daniel T. Chang; J. Shaffer; Bruce G. Haffty; Lynn D. Wilson
Glioblastoma is the most common primary brain tumor in adults. Standard therapy depends on patient age and performance status but principally involves surgical resection followed by a 6-wk course of radiation therapy given concurrently with temozolomide chemotherapy. Despite such treatment, prognosis remains poor, with a median survival of 16 mo. Challenges in achieving local control, maintaining quality of life, and limiting toxicity plague treatment strategies for this disease. Radiotherapy dose intensification through hypofractionation and stereotactic radiosurgery is a promising strategy that has been explored to meet these challenges. We review the use of hypofractionated radiotherapy and stereotactic radiosurgery for patients with newly diagnosed and recurrent glioblastoma.
Abdominal Radiology | 2017
Aya Kino; J. Shaffer; Katherine E. Maturen; Heiko Schmiedeskamp; Albert C. Koong; Daniel T. Chang; Dominik Fleischmann; Aya Kamaya
Objectives We sought to determine if carbohydrate antigen 19-9 (CA19-9 ) nadir (nCA19-9), time to nadir (TTN), and doubling time (DT) after radiotherapy (RT) correlate with outcomes in pancreatic ductal adenocarcinoma. Methods We examined the records of 102 patients treated with RT for primary, nonmetastatic pancreatic ductal adenocarcinoma between August 1998 and July 2011. Of these, 33 patients were treated with postoperative chemoradiotherapy (PORT) and 69 patients with definitive chemoradiotherapy (CRT). Results Among the patients treated with PORT, TTN and DT were associated with both overall survival (OS; P = <0.01 for both) and freedom from progression (FFP; P = <0.01 for both). In patients treated with CRT, nCA19-9 and TTN correlated with both OS (P = <0.01 and P = 0.02, respectively) and FFP (P = 0.01 and <0.01, respectively). On multivariable analysis, in patients treated with PORT, TTN remained independently correlated with OS and FFP (P = 0.01; hazard ratios [HR], 6.43 and P = 0.02; HR, 4.00, respectively), whereas DT remained independently correlated to FFP (P = 0.04; HR, 0.27). In patients treated with CRT, controlling for pretreatment CA19-9, nCA19-9 and TTN independently correlated with OS (P = <0.01; HR, 3.0 and P = 0.03; HR, 2.56, respectively) and FFP (P = 0.04; HR, 2.31 and P = <0.01; HR, 4.0, respectively). Conclusions CA19-9 kinetics after RT correlate with disease progression and survival and could serve as a prognostic tool to guide treatment decisions.
International Journal of Radiation Oncology Biology Physics | 2014
D.T. Chang; J. Shaffer; Erqi L. Pollom; Matthew H. Stenmark; M. Tang; K.W. Merrell; Percy Lee; Kenneth R. Olivier; Albert C. Koong; Mary Feng