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Peter W. T. Pisters

The University of Texas MD Anderson Cancer Center

Publishes on Pancreatic and Hepatic Oncology Research, Sarcoma Diagnosis and Treatment, Gastrointestinal Tumor Research and Treatment. 385 papers and 40.1k citations.

385Publications
40.1kTotal Citations

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Analysis of prognostic factors in 1,041 patients with localized soft tissue sarcomas of the extremities.
Peter W. T. Pisters, Denis H. Y. Leung, James M. Woodruff et al.|Journal of Clinical Oncology|1996
Cited by 1.2kOpen Access

PURPOSE: To identify specific independent adverse clinicopathologic factors for event-free survival in a cohort of consecutively treated patients with extremity soft tissue sarcomas. PATIENTS AND METHODS: Prospectively collected data from a population of 1,041 adult patients with localized (American Joint Committee on Cancer [AJCC] stage IA to IIIB) extremity soft tissue sarcomas were analyzed. Patients were treated at a single institution between 1982 and 1994. Patient, tumor, and pathologic factors were analyzed by univariate and multivariate techniques to identify independent prognostic factors for the end points of local recurrence, distant recurrence, disease-specific survival, and post-metastasis survival. RESULTS: The 5-year survival rate for this cohort of patients was 76%, with a median follow-up time of 3.95 years. Significant independent adverse prognostic factors for local recurrence were age greater than 50 years, recurrent disease at presentation, microscopically positive surgical margins, and the histologic subtypes fibrosarcoma and malignant peripheral-nerve tumor. For distant recurrence, intermediate tumor size, high histologic grade, deep location, recurrent disease at presentation, leiomyosarcoma, and nonliposarcoma histology were independent adverse prognostic factors. For disease-specific survival, large tumor size, high grade, deep location, recurrent disease at presentation, the histologic subtypes leiomyosarcoma and malignant peripheral-nerve tumor, microscopically positive surgical margins, and lower extremity site were adverse factors. For post-metastasis survival, only large tumor size ( > 10 cm) was an adverse prognostic factor. CONCLUSION: The independent adverse prognostic factors for distant recurrence and disease specific survival differ from those identified for subsequent local recurrence. Patients with microscopically positive surgical margins or patients who present with locally recurrent disease are at increased risk for subsequent local recurrence and tumor-related mortality. Specific histopathologic subtypes are associated with increased risks for local failure and tumor-related mortality.

NCCN Task Force Report: Update on the Management of Patients with Gastrointestinal Stromal Tumors
George D. Demetri, Margaret von Mehren, Cristina R. Antonescu et al.|Journal of the National Comprehensive Cancer Network|2010
Cited by 1.2k

The standard of care for managing patients with gastrointestinal stromal tumors (GISTs) rapidly changed after the introduction of effective molecularly targeted therapies involving tyrosine kinase inhibitors (TKIs), such as imatinib mesylate and sunitinib malate. A better understanding of the molecular characteristics of GISTs have improved the diagnostic accuracy and led to the discovery of novel immunomarkers and new mechanisms of resistance to TKI therapy, which in turn have resulted in the development of novel treatment strategies. To address these issues, the NCCN organized a task force consisting of a multidisciplinary panel of experts in the fields of medical oncology, surgical oncology, molecular diagnostics, and pathology to discuss the recent advances, identify areas of future research, and recommend an optimal approach to care for patients with GIST at all stages of disease. The task force met for the first time in October 2003 and again in December 2006 and October 2009. This supplement describes the recent developments in the field of GIST as discussed at the October 2009 meeting.

Effect of Laparoscopic-Assisted Resection vs Open Resection of Stage II or III Rectal Cancer on Pathologic Outcomes
Cited by 1.1k

IMPORTANCE: Evidence about the efficacy of laparoscopic resection of rectal cancer is incomplete, particularly for patients with more advanced-stage disease. OBJECTIVE: To determine whether laparoscopic resection is noninferior to open resection, as determined by gross pathologic and histologic evaluation of the resected proctectomy specimen. DESIGN, SETTING, AND PARTICIPANTS: A multicenter, balanced, noninferiority, randomized trial enrolled patients between October 2008 and September 2013. The trial was conducted by credentialed surgeons from 35 institutions in the United States and Canada. A total of 486 patients with clinical stage II or III rectal cancer within 12 cm of the anal verge were randomized after completion of neoadjuvant therapy to laparoscopic or open resection. INTERVENTIONS: Standard laparoscopic and open approaches were performed by the credentialed surgeons. MAIN OUTCOMES AND MEASURES: The primary outcome assessing efficacy was a composite of circumferential radial margin greater than 1 mm, distal margin without tumor, and completeness of total mesorectal excision. A 6% noninferiority margin was chosen according to clinical relevance estimation. RESULTS: Two hundred forty patients with laparoscopic resection and 222 with open resection were evaluable for analysis of the 486 enrolled. Successful resection occurred in 81.7% of laparoscopic resection cases (95% CI, 76.8%-86.6%) and 86.9% of open resection cases (95% CI, 82.5%-91.4%) and did not support noninferiority (difference, -5.3%; 1-sided 95% CI, -10.8% to ∞; P for noninferiority = .41). Patients underwent low anterior resection (76.7%) or abdominoperineal resection (23.3%). Conversion to open resection occurred in 11.3% of patients. Operative time was significantly longer for laparoscopic resection (mean, 266.2 vs 220.6 minutes; mean difference, 45.5 minutes; 95% CI, 27.7-63.4; P < .001). Length of stay (7.3 vs 7.0 days; mean difference, 0.3 days; 95% CI, -0.6 to 1.1), readmission within 30 days (3.3% vs 4.1%; difference, -0.7%; 95% CI, -4.2% to 2.7%), and severe complications (22.5% vs 22.1%; difference, 0.4%; 95% CI, -4.2% to 2.7%) did not differ significantly. Quality of the total mesorectal excision specimen in 462 operated and analyzed surgeries was complete (77%) and nearly complete (16.5%) in 93.5% of the cases. Negative circumferential radial margin was observed in 90% of the overall group (87.9% laparoscopic resection and 92.3% open resection; P = .11). Distal margin result was negative in more than 98% of patients irrespective of type of surgery (P = .91). CONCLUSIONS AND RELEVANCE: Among patients with stage II or III rectal cancer, the use of laparoscopic resection compared with open resection failed to meet the criterion for noninferiority for pathologic outcomes. Pending clinical oncologic outcomes, the findings do not support the use of laparoscopic resection in these patients. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00726622.

Long-term results of a prospective randomized trial of adjuvant brachytherapy in soft tissue sarcoma.
Peter W. T. Pisters, L.B. Harrison, Denis H. Y. Leung et al.|Journal of Clinical Oncology|1996
Cited by 999Open Access

PURPOSE: This trial was performed to evaluate the impact of adjuvant brachytherapy on local and systemic recurrence rates in patients with soft tissue sarcoma. PATIENTS AND METHODS: In a single-institution prospective randomized trial, 164 patients were randomized intraoperatively to receive either adjuvant brachytherapy (BRT) or no further therapy (no BRT) after complete resection of soft tissue sarcomas of the extremity or superficial trunk. The adjuvant radiation was administered by iridium-192 implant, which delivered 42 to 45 Gy over 4 to 6 days. The two study groups had comparable distributions of patient and tumor factors, including age, sex, tumor site, tumor size, and histologic type and grade. RESULTS: With a median follow-up time of 76 months, the 5-year actuarial local control rates were 82% and 69% in the BRT and no BRT groups (P = .04), respectively. Patients with high-grade lesions had local control rates of 89% (BRT) and 66% (no BRT) (P = .0025). BRT had no impact on local control in patients with low-grade lesions (P = .49). The 5-year freedom-from-distant-recurrence rates were 83% and 76% in the BRT and no BRT groups (P = .60), respectively. Analysis by histologic grade did not demonstrate an impact of BRT on the development of distant metastasis, despite the improvement in local control noted in patients with high-grade lesions. The 5-year disease-specific survival rates for the BRT and no BRT groups were 84% and 81% (P = .65), respectively, with no impact of BRT regardless of tumor grade. CONCLUSION: Adjuvant brachytherapy improves local control after complete resection of soft tissue sarcomas. This improvement in local control is limited to patients with high-grade histopathology. The reduction in local recurrence in patients with high-grade lesions is not associated with a significant reduction in distant metastasis or improvement in disease-specific survival.