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Peter W T Pisters

Publications and source records attributed to Peter W T Pisters.

At least 19 recordsLinked to original sources
PubMed2007

Periosteal margin in soft-tissue sarcoma.

BACKGROUND: Soft-tissue sarcomas frequently rest in contact with bone. The purpose of the study was to evaluate the risk of local recurrence for sarcomas adjacent to bone and to determine whether the periosteum provides an adequate margin of resection. METHODS: Fifty patients with soft-tissue sarcomas abutting bone were treated at a single institution between 1990 and 2004. All patients had high-grade, T2 (>5 cm), nonmetastatic disease in the lower extremity. Bone contact was verified by preoperative magnetic resonance imaging (MRI) and/or computed tomography (CT) scans. Forty-three of 50 patients received preoperative radiation with a mean dose of 50 Gy. In 11 cases a composite resection of bone and soft tissue was performed. In 39 cases the excision involved only soft tissue. RESULTS: True bone invasion was verified by histopathologic examination in 3 of 50 cases (6%). Local recurrence in the soft tissues developed in 8 of 50 (16%) patients. In no case did the recurrence involve destruction of cortical bone or erosion into bone. The recurrent tumor resided against the region of previous bone contact in 1 of 8 cases. There was no statistically significant difference in local recurrence between patients who had composite bone resection and patients who had soft-tissue resection only (P = .87). CONCLUSIONS: Relatively few sarcomas are able to penetrate cortical bone. Composite bone and soft-tissue resections are indicated primarily for frank bone invasion. In the absence of this, the periosteum is an adequate surgical margin for sarcomas treated with wide excision and radiation.

Adolescent↗
PubMed2007

Surgical resection of gastrointestinal stromal tumors after treatment with imatinib.

BACKGROUND: Surgical resection of gastrointestinal stromal tumors (GISTs) has been the most effective therapy for these rare tumors. Imatinib has been introduced as systemic therapy for locally advanced and metastatic GIST. In this study, the surgical resection rates and long-term outcomes of patients treated with preoperative imatinib for locally advanced primary, recurrent, or metastatic GISTs were evaluated. METHODS: Patients were retrospectively assessed for completeness of surgical resection and for disease-free and overall survival after resection. RESULTS: Forty-six patients underwent surgery after treatment with imatinib. Eleven were treated for locally advanced primary GISTs for a median of 11.9 months, followed by complete surgical resection. All eleven were alive at a median of 19.5 months, and ten were free of disease. Thirty-five patients were treated for recurrent or metastatic GIST. Of these, eleven underwent complete resection. Six of the eleven patients had recurrent disease at a median of 15.1 months. All eleven patients were alive at a median of 30.7 months. Patients with a partial radiographic tumor response to imatinib had significantly higher complete resection rates than patients with progressive disease (91% vs. 4%; P < .001). Of the 24 patients with incomplete resection, 18 initially responded to imatinib but were unable to undergo complete resection after they progressed before surgery. CONCLUSIONS: Preoperative imatinib can decrease tumor volume and is associated with complete surgical resection in locally advanced primary GISTs. Early surgical intervention should be considered for imatinib-responsive recurrent or metastatic GIST, since complete resection is rarely achieved once tumor progression occurs.

Adult↗
PubMed2006

Complications of combined modality treatment of primary lower extremity soft-tissue sarcomas.

BACKGROUND: Correlations between various patient, tumor, and treatment characteristics and complications in patients undergoing combined modality treatment for primary lower extremity soft-tissue sarcomas were investigated. METHODS: Using the M. D. Anderson Radiation Oncology database, the records of the subset of patients treated with combined radiation and limb-sparing surgery for primary lower extremity soft-tissue sarcomas were retrospectively reviewed from the years 1960 to 2003. RESULTS: In all, 412 patients were identified. With a median follow-up of 9.3 years, there were a total of 113 (27%) acute wound complications and 41 (13% at 20 years) chronic radiation-related limb complications. Preoperative radiation and tumor sizes >5 cm were associated with an increased risk of acute wound complications (34% preoperative vs. 16% postoperative, P < .001; and 31% >5 cm vs. 17% < or =5 cm, P = .005). At 20 years the radiation-related complication rate was higher in patients with a groin or thigh tumor location (16% vs. 4% other; P = .008), prior acute wound complications (20% vs. 10% no surgical complication), and a radiation dose > or =60 grays (Gy) (18% vs. 9% for dose < 60 Gy; P = .04). Five fractures occurred, resulting in a crude overall fracture rate of 1.2%. CONCLUSIONS: Patients treated with preoperative radiation for larger tumors are more likely to have acute surgical wound complications. Acute wound complications followed by postoperative radiation are associated with chronic radiation-related limb problems, as are higher radiation dose and proximal tumor location. The fracture rate is so low that prophylactic fixation is not warranted.

Adolescent↗
PubMed2006

Retroperitoneal soft tissue sarcoma: an analysis of radiation and surgical treatment.

PURPOSE: To evaluate the clinical outcomes of patients with localized retroperitoneal soft tissue sarcoma (STS) treated with complete surgical resection and radiation. METHODS AND MATERIALS: The medical records of 83 patients were reviewed retrospectively. Sixty patients presented with primary disease and the remaining 23 had recurrence after previous surgical resection. RESULTS: With a median follow-up of 47 months, the actuarial overall disease-specific survival (DSS), distant metastasis-free survival, and local control (LC) rates were 44%, 67%, and 40%, respectively. Of the 38 patients dying of disease, local disease progression was the sole site of recurrence for 16 patients and was a component of progression for another 11 patients. Multivariate analysis indicated that histologic grade was associated with the 5-year rates of DSS (low-grade, 92%; intermediate-grade, 51%; and high-grade, 41%, p = 0.006). Multivariate analysis also indicated an inferior 5-year LC rate for patients presenting with recurrent disease, positive or uncertain resection margins, and age greater than 65 years. The data did not suggest an improved local control with higher doses of external-beam radiation (EBRT) or with the specific use of intraoperative radiotherapy (IORT). Radiation-related complications (10% at 5 years) developed in 5 patients; all had received their EBRT postoperatively. CONCLUSIONS: Although preoperative radiation therapy and aggressive surgical resection is well tolerated in patients, local disease progression continues to be a significant component of disease death. In this small cohort of patients, the use of higher doses of EBRT or IORT did not result in clinically apparent improvements in outcomes.

Adult↗
PubMed2006

The effect of preoperative radiotherapy and reconstructive surgery on wound complications after resection of extremity soft-tissue sarcomas.

BACKGROUND: Major wound complications (MWCs) are frequent after preoperative radiotherapy (RT) for extremity soft-tissue sarcoma (STS). We examined the rate of MWCs at a single institution with readily available reconstructive surgery. METHODS: The medical records of consecutively treated extremity STS patients treated with preoperative external-beam RT and surgical resection from June 1996 through February 2003 were reviewed. Patients underwent RT (median 50 Gy), followed by resection 4-8 weeks later. Patients believed to be at higher risk for MWC underwent wound closure by the reconstructive surgery service (RSS). MWCs included secondary operation, invasive procedure, hospital readmission, or persistent deep packing or dressing changes. RESULTS: A total of 173 patients underwent preoperative RT. Median age was 54 years; 51% were female; 80% had lower extremity STS. Wound closure was performed by the primary surgeon in 91 cases (53%). The RSS performed wound closure in the remaining 82 patients (47%). One or more MWCs occurred in 55 patients (32%). Wound complications were more likely in patients with lower extremity (49/138, 36%) than upper extremity (6/35, 17%) STS (P = 0.03). Among patients with lower-risk wounds closed by the primary surgical team, 29 (32%) experienced MWC, whereas in the higher-risk patients closed by the RSS, MWC occurred in 26 (32%). CONCLUSIONS: MWCs are frequent after preoperative RT and occur more commonly in patients with lower extremity tumors. The MWC rate observed in a single-institution setting was comparable to that observed in the preoperative therapy arm of a multicenter Canadian trial. Patients believed to be at higher risk for MWCs undergoing RSS closure have MWC rates comparable to those with lower-risk wounds closed by the primary team.

Adolescent↗
PubMed2006

Phase II trial of preoperative chemoradiation in patients with localized gastric adenocarcinoma (RTOG 9904): quality of combined modality therapy and pathologic response.

PURPOSE: Preoperative therapy for localized gastric cancer has considerable appeal. We hypothesized that, in a cooperative group setting, preoperative chemoradiotherapy would induce a 20% pathologic complete response (pathCR) rate. Combined-modality therapy quality, survival, and safety were secondary end points. PATIENTS AND METHODS: Patients with localized gastric adenocarcinoma were eligible. A negative laparoscopic evaluation was required. Patients received two cycles of induction fluorouracil, leucovorin, and cisplatin followed by concurrent radiation and chemotherapy (infusional fluorouracil and weekly paclitaxel). Resection was attempted 5 to 6 weeks after chemoradiotherapy was completed. Quality of therapy was assessed with other end points. RESULTS: Twenty institutions participated. Forty-nine patients were entered and 43 were assessable (12% stage IB; 37% stage II; and 52% stage III). The pathCR and R0 resection rates were 26% and 77%, respectively. At 1 year, more patients with pathCR (82%) are living than those with less than pathCR (69%). Grade 4 toxicity occurred in 21% of patients. Chemotherapy, radiotherapy, and surgery per protocol (including acceptable variations) occurred in 98%, 44%, and 63% of patients, respectively. A D2 dissection was performed in 50% of patients. Of 18 major radiotherapy variations, 17 were due to the lack of inclusion of the L3-4 vertebral interphase as prespecified. CONCLUSION: For localized gastric cancer, preoperative chemoradiotherapy strategy achieved a pathCR rate of more than 20% in a cooperative group setting. The quality of surgery improved (50% with D2 dissection) possibly because surgery was part of this trial. With some refinements, this preoperative chemoradiotherapy strategy is poised for a randomized comparison with postoperative adjuvant chemoradiotherapy in patients with gastric cancer.

Adenocarcinoma↗
PubMed2006

Borderline resectable pancreatic cancer: definitions, management, and role of preoperative therapy.

With recent advances in pancreatic imaging and surgical techniques, a distinct subset of pancreatic tumors is emerging that blurs the distinction between resectable and locally advanced disease: tumors of "borderline resectability." In our practice, patients with borderline-resectable pancreatic cancer include those whose tumors exhibit encasement of a short segment of the hepatic artery, without evidence of tumor extension to the celiac axis, that is amenable to resection and reconstruction; tumor abutment of the superior mesenteric artery involving <180 degrees of the circumference of the artery; or short-segment occlusion of the superior mesenteric vein, portal vein, or their confluence with a suitable option available for vascular reconstruction because the veins are normal above and below the area of tumor involvement. With currently available surgical techniques, patients with borderline-resectable pancreatic head cancer are at high risk for a margin-positive resection. Therefore, our approach to these patients is to use preoperative systemic therapy and local-regional chemoradiation to maximize the potential for an R0 resection and to avoid R2 resections. In our experience, patients with favorable responses to preoperative therapy (radiographical evidence of tumor regression and improvement in serum tumor marker levels) are the subset of patients who have the best chance for an R0 resection and a favorable long-term outcome.

Adult↗
PubMed2006

Retroperitoneal sarcomas: Combined-modality treatment approaches.

Retroperitoneal sarcomas (RPS) are rare tumors, accounting for approximately 15% of soft tissue sarcomas. Surgical resection of localized tumors with gross and microscopically negative margins remains the standard of care. However, because RPS are frequently large and locally advanced, resections are often incomplete, resulting in local recurrence. Investigators are evaluating combined-modality therapies to improve local control and disease-specific survival. This review outlines current concepts and evolving treatment strategies in the diagnosis, staging, and management of RPS.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2006

Retroperitoneal sarcoma: a population-based analysis of epidemiology, surgery, and radiotherapy.

BACKGROUND: No population-based studies of retroperitoneal sarcoma (RPS) have been conducted, and the use and timing of adjuvant radiotherapy for RPS is controversial. The objective of this study was to examine the incidence and treatment of RPS, specifically regarding the use of adjuvant radiotherapy. METHODS: The Surveillance, Epidemiology, and End Results (SEER) database was used to evaluate the incidence of RPS over a 29-year period (1973-2001). The rate of surgery, the rate and timing of adjuvant radiotherapy, and the influence of demographic factors on treatment were evaluated. RESULTS: A total of 2348 cases of RPS were identified. The mean annual incidence of RPS was 2.7 cases per 10(6) persons and did not change significantly over time (2.6 in 1973 vs. 2.8 in 2001; P = .92). Most patients (1654; 70.4%) underwent surgical resection. Radiotherapy was used in 428 patients (25.9%) who underwent surgery; radiation was given postoperatively in 366 (85.5%), preoperatively in 20 (4.7%), and intraoperatively or unknown in 42 (9.8%). Patients who received any adjuvant radiotherapy were on average 5 years younger than those who underwent surgery alone (P < .0001). Radiotherapy was more commonly used among whites than African Americans (25.8% vs. 16.7%; P = .02) and there was significant variation in the use of adjuvant radiotherapy by geographic location (P = .003). On multivariate analysis, race (P = 0.004), age (P < .0001), and geographic location (P = .006) were independently associated with the use of adjuvant radiotherapy. CONCLUSION: The incidence of RPS, a rare disease, appears stable. Most patients who undergo surgery do not receive any adjuvant radiotherapy, and very few receive preoperative radiotherapy. Differences in adjuvant radiotherapy use related to demographic and geographic factors suggest that at least some treatment variations reflect differences in individual and institutional practice patterns.

Adolescent↗
PubMed2006

Intraductal papillary mucinous neoplasms of the pancreas: effect of invasion and pancreatic margin status on recurrence and survival.

BACKGROUND: The natural history and prognosis for patients with intraductal papillary mucinous neoplasms (IPMN) with and without invasion remain poorly defined. This study evaluated the outcome after pancreatectomy for IPMN according to the pancreatic transection margin status and the presence or absence of invasive carcinoma. METHODS: Data from a prospective pancreatic tumor database and medical records were reviewed for all patients who underwent pancreatic resection for IPMN at our institution between July 1990 and July 2003. Surgical specimens were re-reviewed by a single pathologist. RESULTS: IPMN was diagnosed in 35 (26%) of 137 patients who underwent pancreatic resection for cystic neoplasms. Invasive IPMN was confirmed in 13 (37%) of 35 patients. Noninvasive IPMN was found in 22 (63%) of 35 patients; pathology re-review changed the original diagnosis from invasive to noninvasive IPMN in 6 patients. Noninvasive IPMN was found at the final pancreatic margin in eight patients; none developed recurrent disease at a median follow-up of 34 months. Recurrent disease was identified in 7 (58%) of 13 patients with invasive IPMN and in none with noninvasive IPMN. The median overall survival was 22.9 and 84.9 months in patients with invasive and noninvasive IPMN, respectively (P=.0009). CONCLUSIONS: Distinction between invasive and noninvasive IPMN is essential in estimating prognosis and determining the need for adjuvant therapy and the frequency of follow-up surveillance. Noninvasive IPMN, even if present at the pancreatic margin, was not associated with recurrent disease. In contrast, invasive IPMN was associated with early recurrence and short survival.

Adenocarcinoma, Mucinous↗
PubMed2006

Phase I trial evaluating the safety of bevacizumab with concurrent radiotherapy and capecitabine in locally advanced pancreatic cancer.

PURPOSE: To study the safety of bevacizumab with capecitabine-based chemoradiotherapy. PATIENTS AND METHODS: Patients with inoperable pancreatic adenocarcinoma received bevacizumab 2 weeks before radiotherapy (50.4 Gy treating the primary tumor and gross adenopathy), every 2 weeks during radiotherapy (12 patients each at 2.5, 5.0, 7.5, and 10 mg/kg), and after radiotherapy until disease progression. Capecitabine was administered on days 14 through 52 (650 mg/m2 orally twice daily for the first six patients; 825 mg/m2 for the remaining patients). RESULTS: Significant acute gastrointestinal (43% grade 2; 4% grade 3), hand and foot syndrome (21% grade 2), and transient hematologic (8% grade 3 or greater) events were uncommon with protocol mandated dose reductions of capecitabine grade 2 toxicity (43% of patients). Among the first 30 patients treated, three patients had tumor-associated bleeding duodenal ulcers, and one had a contained duodenal perforation. No additional bleeding events occurred among the final 18 patients after patients with duodenal involvement by tumor were excluded. Nine (20%) of 46 assessable patients had confirmed partial responses until distant progression for a median of 6.2 months. Four patients have undergone pancreaticoduodenectomy without perioperative complication. The median survival was 11.6 months (95% CI, 9.6 to 13.6), from the start of protocol therapy. CONCLUSION: Concurrent bevacizumab did not significantly increase the acute toxicity of a relatively well-tolerated chemoradiotherapy regimen. However, ulceration and bleeding in the radiation field possibly related to bevacizumab occurred when tumor involved the duodenal mucosa. The encouraging efficacy end points suggest that the further study of bevacizumab with chemoradiotherapy is warranted.

Adult↗
PubMed2006

Long-term results of two prospective trials of preoperative external beam radiotherapy for localized intermediate- or high-grade retroperitoneal soft tissue sarcoma.

BACKGROUND: The reported data on surgery plus radiotherapy for retroperitoneal soft tissue sarcomas (RPS) have been mostly from retrospective studies. We evaluated the long-term outcome of patients with operable RPS who were treated with protocol-based preoperative radiotherapy followed by complete surgical resection. METHODS: Data from two prospective trials that included preoperative radiotherapy and surgery for patients with radiographically resectable RPS were combined to define long-term relapse rates and survival. RESULTS: Seventy-two patients with intermediate- or high-grade RPS were treated with preoperative radiotherapy (median dose, 45 Gy; range, 18.0-50.4 Gy). Fifty-four patients (75%) had primary RPS, whereas 18 (25%) had recurrent disease. The median tumor size was 15.5 cm. Sixty-four patients completed the planned preoperative radiotherapy; 57 (89%) underwent laparotomy with curative intent, and 54 (95%) had a macroscopically complete (R0 or R1) resection. With a median follow-up of 40.3 months, 28 patients (52%) who received preoperative radiotherapy and underwent a macroscopically complete resection had recurrences. For the 54 patients who underwent R0 or R1 resection after preoperative radiotherapy, the 5-year local recurrence-free, disease-free, and overall survival rates were 60%, 46%, and 61%, respectively. The median overall survival has not been reached (>60 months). CONCLUSIONS: Patients with intermediate- or high-grade RPS treated with preoperative radiotherapy plus complete resection had a median survival >60 months. This compares favorably to historical data for similar patients treated with surgery alone.

Adult↗
PubMed2006

Venous resection in pancreatic cancer surgery.

Vascular resection and reconstruction at the time of pancreaticoduodenectomy (PD) adds complexity to an already demanding operation. In this chapter, we review the indications, surgical techniques, and most recent results of venous resection combined with PD. The need for venous resection may not always be apparent on preoperative imaging, and surgeons who perform PD should be familiar with standard techniques necessary for vascular resection and reconstruction. Recent data suggest that with proper patient selection and surgeon experience, vascular resection and reconstruction can be performed safely and does not impact survival duration even in patients with pancreatic ductal adenocarcinoma. The median survival of patients who underwent PD and required vascular resection was 23 months, approximately 1 year longer than the survival of patients with locally advanced, surgically unresectable pancreatic cancer who receive palliative chemotherapy or chemoradiation.

Humans↗
PubMed2006

The argument for pre-operative chemoradiation for localized, radiographically resectable pancreatic cancer.

Although not universally accepted, chemoradiation is considered a standard adjuvant treatment for patients with resected pancreatic cancer. Theoretical advantages of reduced toxicity and increased efficacy with the use of pre-operative chemoradiation compared to post-operative adjuvant chemoradiation have recently been validated with the publication of a phase III trial in the adjuvant treatment of rectal cancer. Additional advantages of pre-operative chemoradiation that apply specifically to pancreatic cancer include increased access to therapy in patients treated before surgery, addressing the systemic disease recurrence risk without delay, and optimal patient selection for pancreaticoduodenectomy through exclusion of patients with rapidly progressive metastatic disease. Critical components of a pre-operative treatment strategy for pancreatic cancer include adherence to a strict definition of resectability, accurate radiographic staging capable of identifying patients with potentially resectable disease, and a safe and efficient means of obtaining a tissue diagnosis and relieving biliary obstruction. Herein, we discuss the rationale for the use of pre-operative chemoradiation in pancreatic cancer, the results of treatment, and future strategies to address the pattern of disease recurrence.

Angiogenesis Inhibitors↗
PubMed2006

Estimation of the causal effects on survival of two-stage nonrandomized treatment sequences for recurrent diseases.

In the treatment of cancer, patients commonly receive a variety of sequential treatments. The initial treatments administered following diagnosis can vary, as well as subsequent salvage regimens given after disease recurrence. This article considers the situation where neither initial treatments nor salvage treatments are randomized. Assuming there are no unmeasured confounders, we estimate the joint causal effects on survival of initial and salvage treatments, that is, the effects of two-stage treatment sequences. For each individual treatment sequence, we estimate the survival distribution function and the mean restricted survival time. Different treatment sequences are then compared using these estimates and their corresponding covariances. Simulation studies were conducted to evaluate the performance of the methods, including their sensitivity to the violation of the assumption of no unmeasured confounders. The methods are illustrated by a retrospective study of patients with soft tissue sarcoma, which motivated this research.

Analysis of Variance↗
PubMed2005

Angiosarcoma of the breast.

BACKGROUND: Angiosarcoma of the breast is a rare entity. The objectives of this study were to evaluate prognostic factors and determine outcomes in a large contemporary series of patients. METHODS: Clinical and pathologic factors were analyzed in all patients with angiosarcoma of the breast treated between 1990 and 2003. Overall survival (OS) and disease-free survival (DFS) were estimated using the methods of Kaplan and Meier. Multivariate analyses were performed to evaluate prognostic factors. RESULTS: Fifty-five women with angiosarcoma of the breast were identified. The median age was 49.1 years, and the median follow-up time was 3.7 years. The median OS and DFS were 2.96 years and 2.26 years, respectively. For the 32 patients with primary angiosarcoma of the breast 5-year OS was 59%. Twenty-three (42%) patients had received prior radiation therapy for the treatment of breast cancer. These patients with radiation therapy-associated angiosarcoma were on average 30 years older and less likely to present with distant metastatic disease than patients presenting with radiation-naive angiosarcoma of the breast. Although radiation-naive patients appeared to have had better early DFS and OS, the Kaplan-Meier curves were not statistically different between patients with radiation therapy-associated disease and radiation therapy-naive patients. On multivariate analysis, tumor recurrence (P = 0.006) was the only significant adverse prognostic factor noted for OS. CONCLUSIONS: In this series of 55 patients with angiosarcoma of the breast, radiation therapy-naive angiosarcomas occurred in younger patients, but they behaved similarly to radiation therapy-associated angiosarcomas.

Adult↗