Benjamin R Tan

Washington University in St. Louis, San Luis, Missouri, United States

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Publications (53)275.02 Total impact

  • International journal of radiation oncology, biology, physics 11/2015; 93(3):S125. DOI:10.1016/j.ijrobp.2015.07.298 · 4.26 Impact Factor
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    ABSTRACT: Primary liver carcinomas with hepatocellular and cholangiocellular differentiation (b[HB]-PLC) are rare. Surgery offers the best prognosis, but there is a paucity of literature to guide therapy for patients with advanced or unresectable disease. This study aimed to evaluate outcomes of hepatic-directed therapy compared with those of systemic chemotherapy and surgery. A retrospective evaluation of patients with b(HB)-PLC from 1 January 2008 to 1 September 2014 was conducted. The patients were divided into the following four groups: transplantation (TX) group, surgical resection (SX) group, hepatic directed (HD) group, and systemic chemotherapy alone (SC) group. Overall and progression-free survival, treatment response, and clinicopathologic data were analyzed. The study included 79 patients (37 females) with an average age of 62 years. The number of patients in each group were as follows: TX group (n = 6), SX group (n = 27), HD group (n = 18), and SC group (n = 28). The mean follow-up periods were 33 months for the TX group, 17 months for the SX group, 14 months for the HD group, and 7 months for the SX group. Overall, 28 % of the patients had cirrhosis and 35 % had viral hepatitis. The candidates for surgery comprised 42 % of the patients. The HD group (n = 18) had a significantly greater objective response than the SC group (n = 28) (47 vs. 6 %; p = 0.02). Two patients who underwent hepatic arterial infusion pump treatment were downstaged to resection. A trend toward improved OS/PFS was observed in the HD group versus the SC group, although statistically significant. The SX group had significantly improved survival (p < 0.001) as did the transplanted patients. Although surgery offers the best survival for b(HB)-PLC patients, only a minority are candidates for surgery. Because HD therapy showed a superior objective response over SC therapy, it may offer a survival advantage and may downstage patients for surgical resection or transplantation.
    Annals of Surgical Oncology 08/2015; DOI:10.1245/s10434-015-4774-y · 3.93 Impact Factor
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    ABSTRACT: Objectives Adjuvant gemcitabine with or without chemoradiation is a standard therapeutic option for patients with resected pancreatic cancer. The feasibility and toxicity of gemcitabine with docetaxel before and after 5-fluorouracil (5FU)-based chemoradiation in the adjuvant pancreatic and biliary cancer setting were investigated.Methods After a curative-intent resection, eligible patients with pancreaticobiliary cancers were treated with two cycles of gemcitabine and docetaxel followed by 5FU-based chemoradiation. Four weeks after completing chemoradiation, two cycles of gemcitabine and docetaxel were administered. The primary endpoint was the incidence of severe toxicities. Secondary endpoints included disease-free survival (DFS) and overall survival (OS).ResultsFifty patients with pancreaticobiliary cancers were enrolled. Twenty-nine patients had pancreatic cancer whereas 21 patients had biliary tract or ampullary cancers. There was one death as a result of pneumonia, and 15% of patients experienced grade 3 or greater non-haematological toxicities. The median DFS and OS for patients with pancreatic cancer were 9.6 and 17 months, respectively, and for those with resected biliary tract cancer were 12 and 23 months, respectively.Conclusions This combination of gemcitabine and docetaxel with chemoradiation is feasible and tolerable in the adjuvant setting. Future studies utilizing a different gemcitabine/taxane combination and schedule may be appropriate in the adjuvant treatment of both pancreatic cancer and biliary tumours.
    HPB 03/2015; 17(7). DOI:10.1111/hpb.12413 · 2.68 Impact Factor
  • P. Parikh · J. Olsen · B. Tan · S. Hunt · R. Myerson ·

    Radiotherapy and Oncology 12/2014; 111:S98. DOI:10.1016/S0167-8140(15)30360-1 · 4.36 Impact Factor
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    ABSTRACT: Background Retrospective studies indicate associations between TSER (thymidylate synthase enhancer region) genotypes and clinical outcomes in patients receiving 5-FU based chemotherapy, but well-controlled prospective validation has been lacking. Methods In this phase II study (NCT00515216 registered through,, patients with “good risk” TSER genotypes (at least one TSER*2 allele) were treated with FOLFOX chemotherapy to determine whether prospective patient selection can improve overall response rates (ORR) in patients with gastric and gastroesophageal junction (GEJ) cancers, compared with historical outcomes in unselected patients (estimated 43%). Results The ORR in genotype-selected patients was 39.1% (9 partial responses out of 23 evaluable patients, 95% CI, 22.2 to 59.2), not achieving the primary objective of improving ORR. An encouraging disease control rate (DCR, consisting of partial responses and stable diseases) of 95.7% was noted and patients with homozygous TSER*2 genotype showed better tumor response. Conclusions In this first prospective, multi-institutional study in patients with gastric or GEJ cancers, selecting patients with at least one TSER*2 allele did not improve the ORR but led to an encouraging DCR. Further studies are needed to investigate the utility of selecting patients homozygous for the TSER*2 allele and additional genomic markers in improving clinical outcomes for patients with gastric and GEJ cancers. Trial Registration NCT00515216
    PLoS ONE 09/2014; 9(9):e107424. DOI:10.1371/journal.pone.0107424 · 3.23 Impact Factor

  • International journal of radiation oncology, biology, physics 09/2014; 90(1):S712-S713. DOI:10.1016/j.ijrobp.2014.05.2084 · 4.26 Impact Factor

  • International journal of radiation oncology, biology, physics 09/2014; 90(1):S400-S401. DOI:10.1016/j.ijrobp.2014.05.1278 · 4.26 Impact Factor

  • International journal of radiation oncology, biology, physics 09/2014; 90(1):S34. DOI:10.1016/j.ijrobp.2014.05.144 · 4.26 Impact Factor
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    ABSTRACT: Objective Oxaliplatin, a component of chemotherapy for colorectal carcinoma liver metastases, can result in hepatic sinusoidal injury; rarely, the injury is fatal. The manifestations of injury are variable. There are no known predictors of susceptibility and outcome. A semi-quantitative system for assessing histological features in non-tumor liver was designed to compare with clinical short-term and long-term outcomes. MethodsA review of 47 patients with metastatic colorectal carcinoma who received liver resection utilizing a system for an aggregate liver injury score (0-4) included hepatocellular and sinusoidal features. Immunohistochemistry (IHC) for aberrant capillarization was included. The proliferation of hepatocytes and sinusoidal lining cells was evaluated with Ki-67 stain. ResultsIn total, 32 (68.1%) cases showed light microscopic lesions of oxaliplatin-induced liver injury, in which 26 were moderate to severe. Elevated preoperative aspartate aminotransferase (AST) and alkaline phosphatase levels were noted with higher injury scores (P=0.01). Patients with higher injury scores had no significant increase in short-term postoperative complications, with one notable exception, who died of liver failure 10 months postoperatively. Increased CD34 expression was associated with higher injury scores (P=0.00004), and abnormal AST levels (P=0.04). Preoperative use of bevacizumab was not associated with lower injury scores. Steatosis was correlated with body mass index (P=0.052) but not with exposure to oxaliplatin, bevacizumab or irinotecan. Conclusions The proposed liver injury scoring system encompasses the spectrum of sinusoidal and hepatocellular lesions in oxaliplatin-induced liver injury and is correlated with serum liver enzyme levels in this group. Most patients recovered without complications during the 93-month follow-up, indicating that these lesions are reversible.
    Journal of Digestive Diseases 07/2014; 15(10). DOI:10.1111/1751-2980.12177 · 1.96 Impact Factor
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    ABSTRACT: This study aimed to determine the maximum-tolerated dose and dose-limiting toxicities of pegylated liposomal doxorubicin (PLD) in combination with temsirolimus (T) in patients with refractory solid tumors. Using a standard “3+3” dose escalation design, 23 patients were enrolled in three dosing cohorts in this phase I study. The starting dose level was PLD at 30 mg/m2 every 4 weeks and T at 20 mg weekly. Pharmacokinetics (PK) of doxorubicin were evaluated for patients in the expansion cohort. The most common treatment-related adverse events of all grades were mucositis/stomatitis (69.6 %), anorexia (52.2 %), thrombocytopenia (52.2 %), and fatigue (47.8 %). The recommended doses of this combination for phase II studies are 25 mg/m2 PLD and 25 mg T. PK analyses suggested increased exposure of doxorubicin in this combination regimen compared to doxorubicin administered as a single agent, possibly due to PK drug interactions. Out of 18 patients evaluable for a treatment response, two had partial responses (PR) (breast cancer and hepatocellular carcinoma) and six had stable disease (SD). Two patients remained on treatment for more than 1 year. The combination of PLD and T is tolerable, and the treatment resulted in clinical benefit. The combination regimen should be further explored in appropriate tumor types. Electronic supplementary material The online version of this article (doi:10.1007/s00280-014-2493-x) contains supplementary material, which is available to authorized users.
    Cancer Chemotherapy and Pharmacology 06/2014; 74(2). DOI:10.1007/s00280-014-2493-x · 2.77 Impact Factor
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    ABSTRACT: Background Preoperative radiation therapy with 5-fluorouracil chemotherapy is a standard of care for cT3-4 rectal cancer. Studies incorporating additional cytotoxic agents demonstrate increased morbidity with little benefit. We evaluate a template that: (1) includes the benefits of preoperative radiation therapy on local response/control; (2) provides preoperative multidrug chemotherapy; and (3) avoids the morbidity of concurrent radiation therapy and multidrug chemotherapy. Methods and Materials Patients with cT3-4, any N, any M rectal cancer were eligible. Patients were confirmed to be candidates for pelvic surgery, provided response was sufficient. Preoperative treatment was 5 fractions radiation therapy (25 Gy to involved mesorectum, 20 Gy to elective nodes), followed by 4 cycles of FOLFOX [5-fluorouracil, oxaliplatin, leucovorin]. Extirpative surgery was performed 4 to 9 weeks after preoperative chemotherapy. Postoperative chemotherapy was at the discretion of the medical oncologist. The principal objectives were to achieve T stage downstaging (ypT < cT) and preoperative grade 3+ gastrointestinal morbidity equal to or better than that of historical controls. Results 76 evaluable cases included 7 cT4 and 69 cT3; 59 (78%) cN+, and 7 cM1. Grade 3 preoperative GI morbidity occurred in 7 cases (9%) (no grade 4 or 5). Sphincter-preserving surgery was performed on 57 (75%) patients. At surgery, 53 patients (70%) had ypT0-2 residual disease, including 21 (28%) ypT0 and 19 (25%) ypT0N0 (complete response); 24 (32%) were ypN+. At 30 months, local control for all evaluable cases and freedom from disease for M0 evaluable cases were, respectively, 95% (95% confidence interval [CI]: 89%-100%) and 87% (95% CI: 76%-98%). Cases were subanalyzed by whether disease met requirements for the recently activated PROSPECT trial for intermediate-risk rectal cancer. Thirty-eight patients met PROSPECT eligibility and achieved 16 ypT0 (42%), 15 ypT0N0 (39%), and 33 ypT0-2 (87%). Conclusion This regimen achieved response and morbidity rates that compare favorably with those of conventionally fractionated radiation therapy and concurrent chemotherapy.
    International journal of radiation oncology, biology, physics 03/2014; 88(4):829–836. DOI:10.1016/j.ijrobp.2013.12.028 · 4.26 Impact Factor
  • Gayathri Nagaraj · Yousef Zarbalian · Karin Flora · Benjamin R Tan ·
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    ABSTRACT: Small bowel adenocarcinoma is an uncommon gastrointestinal malignancy with limited data on effective chemotherapy in the adjuvant setting, as well as for advanced disease. We present a case report of a patient with recurrent duodenal adenocarcinoma after resection and adjuvant chemotherapy who experienced a complete response to bevacizumab with oxaliplatin and 5FU (FOLFOX) followed by bevacizumab/capecitabine maintenance therapy for 2 years. The patient continues to be disease-free 8 years after his recurrence. This case highlights the potential of vascular endothelial growth factor (VEGF) inhibitors to enhance chemotherapeutic regimens for advanced small bowel adenocarcinoma.
    Journal of gastrointestinal oncology 02/2014; 5(1):E1-6. DOI:10.3978/j.issn.2078-6891.2013.038
  • J.R. Olsen · P.J. Parikh · S. Hunt · B. Tan · R.J. Myerson ·

    International Journal of Radiation OncologyBiologyPhysics 10/2013; 87(2):S88. DOI:10.1016/j.ijrobp.2013.06.227 · 4.26 Impact Factor
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    ABSTRACT: The prevalence of vitamin D deficiency among patients with cancer has been previously reported. Because vitamin D is fat soluble, patients with pancreatic adenocarcinoma may have an especially high risk of vitamin D deficiency in association with ongoing and varying degrees of malabsorption. However, little is known about the correlation between vitamin D status and prognosis in these patients. We conducted a retrospective review of vitamin D status in patients with pancreatic adenocarcinoma who were treated at Siteman Cancer Center. Patients' demographic information, clinical staging at the time of vitamin D assessment, vitamin D levels, and survival data were collected. Vitamin D deficiency was defined as a serum 25-hydroxyvitamin D (25[OH]D) level of less than 20 ng/mL, and vitamin D insufficiency was defined as a 25(OH)D level of between 20 ng/mL and 30 ng/mL. Between December 2007 and June 2011, 178 patients with pancreatic adenocarcinoma had their vitamin D levels checked at the time of initial visit at this center. Of these 178 patients, 87 (49%) had vitamin D deficiency, and 44 (25%) had vitamin D insufficiency. The median 25(OH)D level was significantly lower among nonwhite patients and among patients with stage I and II disease. A 25(OH)D level of less than 20 ng/mL was found to be associated with poor prognosis (p = 0.0019) in patients with stage III and IV disease. Vitamin D insufficiency and deficiency were prevalent among patients with pancreatic adenocarcinoma. The vitamin D level appears to be prognostic for patients with advanced pancreatic adenocarcinoma, and its effects should be further examined in a prospective study.
    Journal of Translational Medicine 09/2013; 11(1):206. DOI:10.1186/1479-5876-11-206 · 3.93 Impact Factor
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    ABSTRACT: Our purpose was to determine whether geriatric assessments are associated with completion of a chemotherapy course, grade III/IV toxicity or survival in older adults with cancer. In this prospective cohort study, patients aged 65 years and older with colorectal, lung, or breast cancer or lymphoma completed a brief geriatric assessment prior to chemotherapy. Endpoints included completion of the planned number of chemotherapy cycles, grade III/IV toxicity and survival. Multivariate logistic regression determined which factors were independently associated with completion of therapy, grade III/IV toxicity or death. Sixty-five patients were enrolled in the study. The median age was 73 years (range 65-89). Geriatric syndromes were common, including depression (21.5%), dependence on others to carry out instrumental activities of daily living (38.5%) and activities of daily living (10.8%), and comorbidities (mild 47.7%, moderate 20%, severe 15.4%). Of the 65 participants, 67.6% completed the planned number of chemotherapy cycles. Curative intent therapy [OR 4.97 (95% CI 1.21-18.81)], Eastern Cooperative Oncology Group (ECOG) performance status 2-3 [OR 0.089 (0.015-0.53)] and renal function [OR 1.03 (1.00-1.06) per ml/min] were significantly associated with therapy completion. Furthermore, 31.1% experienced grade III/IV non-hematologic toxicity. Moderate to severe comorbidities significantly increased the risk of grade III/IV non-hematologic toxicity [OR 6.13 (1.65-22.74)]. Patients who received chemotherapy with curative intent had lower mortality [HR 0.15 (0.06-0.42)], while patients who reported a fall in the month prior to chemotherapy had an increased risk of death [HR 3.20 (1.13-9.11)]. Geriatric assessment is associated with completion of a planned number of cycles of chemotherapy, grade III/IV non-hematologic toxicity and mortality.
    Journal of Geriatric Oncology 07/2013; 4(3):227-234. DOI:10.1016/j.jgo.2013.02.002 · 1.86 Impact Factor
  • Daniel K Mullady · Benjamin R Tan ·
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    ABSTRACT: Management of patients with gastrointestinal stromal tumor (GIST) typically involves a combination of surgical, pathologic, and pharmacologic interventions. Gastroenterologists are often the first specialists to encounter patients presenting with GIST and are therefore responsible for facilitating early intervention strategies. Although patients with gastric or small-bowel GISTs typically present with symptoms, a diagnosis of GIST should be considered whenever a submucosal lesion is seen endoscopically. Visualization by standard endoscopy often can determine tumor location and size, although endoscopic ultrasound (EUS) is the most accurate imaging technique for submucosal lesions. Biopsy techniques that yield sufficient tumor samples for diagnostic studies, such as EUS-guided fine needle aspiration, are essential, although other approaches such as EUS-guided core needle biopsy may increase diagnostic yield for subepithelial lesions. Pathology assessment should include immunohistochemical staining for KIT and possibly DOG1 expression, and mutational analysis can have prognostic and predictive value for certain patients. R0 resection is the goal for patients with localized or potentially resectable tumors, which often can be accomplished by laparoscopic resection, even for larger tumors. Medical oncologists play a key role in assessing risk of recurrence after resection and optimizing tyrosine kinase inhibitor therapy in the adjuvant or metastatic setting. Cytoreductive surgery may have value for patients with recurrent or metastatic GIST who exhibit stable disease or respond to tyrosine kinase inhibitor therapy. A coordinated multidisciplinary approach over the course of the disease will serve to enhance communication among GIST team members, reduce risk of progression, and optimize outcomes.
    Journal of clinical gastroenterology 06/2013; 47(7). DOI:10.1097/MCG.0b013e3182936c87 · 3.50 Impact Factor

  • Journal of Geriatric Oncology 10/2012; 3:S82. DOI:10.1016/j.jgo.2012.10.098 · 1.86 Impact Factor
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    ABSTRACT: : Delayed repeated intraperitoneal chemotherapy after cytoreductive surgery for carcinomatosis may be an alternative to intraoperative hyperthermic infusion. : The aim of this study was to evaluate the safety and feasibility of delayed repeated intraperitoneal chemotherapy after cytoreduction of colorectal and appendiceal carcinomatosis and pseudomyxoma peritonei. : This study constitutes a retrospective case series. : This study was conducted at a single institution. : A total of 31 patients with peritoneal carcinomatosis (23) and pseudomyxoma peritonei (8) were included. : Cytoreduction was followed by placement of an adhesion barrier and intraperitoneal catheters. Peritoneal scintigraphy preceded biweekly intraperitoneal 5-fluorouracil and systemic combination chemotherapy with leucovorin, fluorouracil, and oxaliplatin (FOLFOX). : The primary outcomes measured are safety, feasibility, and short-term survival. : Cytoreduction to a score of 0 to 1 was possible in 25 patients (80%). Complications occurred in 16 patients (51.6%) and were confined to grades I to III. There were no deaths, and no digestive fistulae occurred. Port malfunction or complication resulted in removal in 5 patients (16.1%). Intraperitoneal chemotherapy was possible in 83.8% of patients; 55% completed the full course. Peritoneal scintigraphy demonstrated free diffusion of tracer in 18 patients (58%), 4 (12.9%) had diffusion in each gutter with limited communication, 5 (16.1%) had limited diffusion around each catheter without communication, and 2 (6.5%) had no diffusion on scintigraphy. Overall survival for peritoneal carcinomatosis was 44.5% at 3 years (95% CI = 23%-65%). : The nonrandomized nature of this study and the early experience are limitations. : Delayed repeated intraperitoneal and systemic chemotherapy after cytoreduction is feasible and has acceptable morbidity rates. Delayed intraperitoneal chemotherapy is possible in 83% of patients.
    Diseases of the Colon & Rectum 10/2012; 55(10):1044-52. DOI:10.1097/DCR.0b013e318265ad42 · 3.75 Impact Factor
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    ABSTRACT: Combination chemotherapy with FOLFIRINOX (oxaliplatin, irinotecan, fluorouracil, and leucovorin) was shown to be effective in a large phase III trial. The purpose of this study was to examine the tolerance and effectiveness of FOLFIRINOX as practiced outside of the confines of a clinical trial and to document any dose modifications used by practicing oncologists. Data on patients with all stages of pancreatic adenocarcinoma treated with FOLFIRINOX at three institutions was analyzed for efficacy, tolerance, and use of any dose modifications. Total of 61 patients was included in this review. Median age was 58 years (range: 37 to 72 years), 33 were male (54.1%) and majority had ECOG performance of 0 or 1 (86.9%, 53 patients). Thirty-eight (62.3%) had metastatic disease, while 23 (37.7%) were treated for locally advanced or borderline resectable disease. Patients were treated with a median number of four cycles of FOLFIRINOX, with dose modifications in 58.3% (176/302) of all cycles. Ten patients had stable disease (16.4%), four had a partial response (6.6%) while eight had progressive disease (13.1%) on best imaging following therapy. Median progression-free survival and overall survival were 7.5 months and 13.5 months, respectively. The most common grade 3-4 adverse event was neutropenia at 19.7% (12 cases), with 4.9% (3 cases) rate of febrile neutropenia. Twenty-one patients (34.4%) were hospitalized as a result of therapy but there were no therapy-related deaths. Twenty-three (37.7%) had therapy eventually discontinued as a result of adverse events. Despite substantial rates of adverse events and use of dose modifications, FOLFIRINOX was found to be clinically effective in both metastatic and non-metastatic patients. Regimen toxicity did not detract from overall response and survival.
    JOP: Journal of the pancreas 09/2012; 13(5):497-501. DOI:10.6092/1590-8577/913
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    ABSTRACT: Purpose: This phase I study was conducted to determine the safety profile and maximum tolerated dose (MTD) of IMP321, a soluble lymphocyte activation gene-3 (LAG-3) Ig fusion protein and MHC Class II agonist, combined with gemcitabine in patients with advanced pancreatic adenocarcinoma. Patients and methods: Patients with advanced pancreatic adenocarcinoma were treated with gemcitabine (1,000 mg/m(2))(level 1), gemcitabine (1,000 mg/m(2)) plus IMP 321 at 0.5 mg (level 2) and 2.0 mg (level 3), respectively. Safety, toxicity, and immunological markers at baseline and post treatment were assessed. Results: A total of 18 patients were enrolled to the study, and 17 were evaluable for toxicity. None of the 6 patients who received 0.5 mg IMP321 experienced IMP321-related adverse events. Of the 5 patients who received IMP321 at the 2 mg dose level, 1 experienced rash, 1 reported hot flashes and 2 had mild pain at the injection sites. No severe adverse events previously attributed to IMP321 were observed. No significant differences were observed when comparing pre- and post-treatment levels of monocytes (CD11b+CD14+), conventional dendritic cells (CD11c+) or T cell subsets (CD4, CD8). Conclusions: IMP321 in combination with gemcitabine is a well-tolerated regimen. IMP321 did not result in any severe adverse events. No incremental activity observed for the additional IMP 321 to gemcitabine at the dose levels evaluated, likely due to sub-optimal dosing. Immunological markers suggested that higher dose levels of IMP321 are needed for future clinical studies.
    Investigational New Drugs 08/2012; 31(3). DOI:10.1007/s10637-012-9866-y · 2.92 Impact Factor