Rita A. Kandel

Preoperative versus postoperative radiotherapy in soft-tissue sarcoma of the limbs: a randomised trial

BACKGROUND External-beam radiotherapy (delivered either preoperatively or postoperatively) is frequently used in local management of sarcomas in the soft tissue of limbs, but the two approaches differ substantially in their potential toxic effects. We aimed to determine whether the timing of external-beam radiotherapy affected the number of wound healing complications in soft-tissue sarcoma in the limbs of adults. METHODS After stratification by tumour size (< or = 10 cm or >10 cm), we randomly allocated 94 patients to preoperative radiotherapy (50 Gy in 25 fractions) and 96 to postoperative radiotherapy (66 Gy in 33 fractions). The primary endpoint was rate of wound complications within 120 days of surgery. Analyses were per protocol for primary outcomes and by intention to treat for secondary outcomes. FINDINGS Median follow-up was 3.3 years (range 0.27-5.6). Four patients, all in the preoperative group, did not undergo protocol surgery and were not evaluable for the primary outcome. Of those patients who were eligible and evaluable, wound complications were recorded in 31 (35%) of 88 in the preoperative group and 16 (17%) of 94 in the postoperative group (difference 18% [95% CI 5-30], p=0.01). Tumour size and anatomical site were also significant risk factors in multivariate analysis. Overall survival was slightly better in patients who had preoperative radiotherapy than in those who had postoperative treatment (p=0.0481). INTERPRETATION Because preoperative radiotherapy is associated with a greater risk of wound complications than postoperative radiotherapy, the choice of regimen for patients with soft-tissue sarcoma should take into account the timing of surgery and radiotherapy, and the size and anatomical site of the tumour.

Porous calcium polyphosphate scaffolds for bone substitute applications -- in vitro characterization.

Porous structures were formed by gravity sintering calcium polyphosphate (CPP) particles of either 106-150 or 150-250 microm size to form samples with 30-45 vol% porosity with pore sizes in the range of 100 microm (40-140 microm). Tensile strength of the samples assessed by diametral compression testing indicated relatively high values for porous ceramics with a maximum strength of 24.1 MPa for samples made using the finer particles (106-150 microm). X-ray diffraction studies of the sintered samples indicated the formation of beta-CPP from the starting amorphous powders. In vitro aging in 0.1 M tris-buffered solution (pH 7.4) or 0.05 M potassium hydrogen phthalate buffered solution (pH 4.0) at 37 degreesC for periods up to 30d indicated an initial rapid loss of strength and P elution by 1 d followed by a more gradual continuing strength and P loss resulting in strengths at 30d equal to about one-third the initial value. The observed structures, strengths and in vitro degradation characteristics of the porous CPP samples suggested their potential usefulness as bone substitute materials pending subsequent in vivo behaviour assessment.

Side Population Cells Isolated from Mesenchymal Neoplasms Have Tumor Initiating Potential

Although many cancers are maintained by tumor-initiating cells, this has not been shown for mesenchymal tumors, in part due to the lack of unique surface markers that identify mesenchymal progenitors. An alternative technique to isolate stem-like cells is to isolate side population (SP) cells based on efflux of Hoechst 33342 dye. We examined 29 mesenchymal tumors ranging from benign to high-grade sarcomas and identified SP cells in all but six samples. There was a positive correlation between the percentage of SP cells and the grade of the tumor. SP cells preferentially formed tumors when grafted into immunodeficient mice, and only cells from tumors that developed from the SP cells had the ability to initiate tumor formation upon serial transplantation. Although SP cells are able to efflux rhodamine dye in addition to Hoechst 33342, we found that the ability to efflux rhodamine dye did not identify a population of cells enriched for tumor-initiating capacity. Here, we identify a subpopulation of cells within a broad range of benign and malignant mesenchymal tumors with tumor-initiating capacity. In addition, our data suggest that the proportion of SP cells could be used as a prognostic factor and that therapeutically targeting this subpopulation of cells could be used to improve patient outcome.

Residual Disease following Unplanned Excision of a Soft-Tissue Sarcoma of an Extremity*

Sixty-five patients who had been referred to our unit for additional management after an unplanned excision of a soft-tissue sarcoma of an extremity at another institution were studied retrospectively to determine the prevalence of residual tumor and to identify factors that predict which patients will have a tumor following such an excision. Unplanned excision was defined as excisional biopsy or unplanned resection of the lesion without benefit of preoperative imaging and without regard for the necessity to resect the lesion with a margin of normal tissue. In each patient, histological evaluation of the specimen removed at the unplanned excision had demonstrated positive resection margins, but postoperative physical examination on our unit revealed no gross evidence of residual tumor and no tumor was identified on cross-sectional imaging of the local site. Patients who had evidence of residual disease on physical examination or on imaging were thought to have definite evidence of sarcoma at the site of the operative wound and were therefore excluded from the study. After multidisciplinary consultation, all patients had a repeat resection at our cancer center. Extensive pathological sampling of the specimen from this second procedure was carried out, with sections obtained at mean intervals of 1.2 ± 0.7 centimeters. Nodules initially thought to indicate disease were identified grossly in twenty-seven (42 per cent) of the sixty-five patients, but histological evaluation confirmed the presence of tumor in only sixteen (59 per cent). Histological evidence of sarcoma was identified in seven additional patients in whom gross nodules were not apparent in the specimen. Thus, sarcoma was identified in a total of twenty-three (35 per cent) of the sixty-five patients. The mean duration of follow-up was forty-six months (range, twenty-four to eighty months; median, thirty-nine months). The margins of the second resection were positive in nine (39 per cent) of the twenty-three patients who had residual sarcoma. Five (22 per cent) of the twenty-three had a local recurrence. Four of the five patients who had a local recurrence had positive margins on repeat resection. This rate of local recurrence (five of twenty-three patients) was significantly higher than that in the remainder of our patients who had a soft-tissue sarcoma of an extremity (sixteen [7 per cent] of 227) (p = 0.03). There was no association between the detection of sarcoma at the second procedure and the initial size or grade of the tumor, the use of irradiation preoperatively, or the interval between the initial, unplanned excision and referral to our cancer center. These data indicate that it is not possible to predict which patients will have residual tumor at the site of the operative wound. Therefore, it is prudent to advise repeat excision for all patients who have had an unplanned excision of a soft-tissue sarcoma of an extremity. Unplanned excision complicates decision-making in the treatment of this disease and should be avoided.

Function and Health Status Outcomes in a Randomized Trial Comparing Preoperative and Postoperative Radiotherapy in Extremity Soft Tissue Sarcoma

PURPOSE Morbidity associated with wound complications may translate into disability and quality-of-life disadvantages for patients treated with radiotherapy (RT) for soft tissue sarcoma (STS) of the extremities. Functional outcome and health status of extremity STS patients randomized in a phase III trial comparing preoperative versus postoperative RT is described. PATIENTS AND METHODS One hundred ninety patients with extremity STS were randomized after stratification by tumor size dichotomized at 10 cm. Function and quality of life were measured by the Musculoskeletal Tumor Society Rating Scale (MSTS), the Toronto Extremity Salvage Score (TESS), and the Short Form-36 (SF-36) at randomization, 6 weeks, and 3, 6, 12, and 24 months after surgery. RESULTS One hundred eighty-five patients had function data. Patients treated with postoperative RT had better function with higher MSTS (25.8 v 21.3, P <.01), TESS (69.8 v 60.6, P =.01), and SF-36 bodily pain (67.7 v 58.5, P =.03) scores at 6 weeks after surgery. There were no differences at later time points. Scores on the physical function, role-physical, and general health subscales of the SF-36 were significantly lower than Canadian normative data at all time points. After treatment arm was controlled for, MSTS change scores were predicted by a lower-extremity tumor, a large resection specimen, and motor nerve sacrifice; TESS change scores were predicted by lower-extremity tumor and prior incomplete excision. When wound complication was included in the model, patients with complications had lower MSTS and TESS scores in the first 2 years after treatment. CONCLUSION The timing of RT has minimal impact on the function of STS patients in the first year after surgery. Tumor characteristics and wound complications have a detrimental effect on patient function.

Tumor Necrosis Factorα Modulates Matrix Production and Catabolism in Nucleus Pulposus Tissue

Study Design. This study examines changes in the production of extracellular matrix molecules as well as the induction of tissue degradation in in vitro formed nucleus pulposus (NP) tissues following incubation with tumor necrosis factor (TNF)&agr;. Objective. To characterize the response of NP cells to TNF-&agr;, a proinflammatory cytokine present in herniated NP tissues. Summary of Background Data. TNF-&agr; is a proinflammatory cytokine expressed by NP cells of degenerate intervertebral discs. It is implicated in the pain associated with disc herniation, although its role in intervertebral disc degeneration remains poorly understood. Methods. In vitro formed NP tissues were treated with TNF-&agr; (up to 50 ng/mL) over 48 hours. Tissues were assessed for histologic appearance, proteoglycan and collagen contents, as well as proteoglycan and collagen synthesis. Reverse transcriptase polymerase chain reaction was used to determine the effect of TNF-&agr; on NP cell gene expression. Proteoglycan degradation was assessed by immunoblot analysis. Results. At doses of 1–5 ng/mL, TNF-&agr; induced multiple cellular responses, including: decreased expression of both aggrecan and type II collagen genes; decreases in the accumulation and overall synthesis of aggrecan and collagen; increased expression of MMP-1, MMP-3, MMP-13, ADAM-TS4, and ADAM-TS5; and induction of ADAM-TS dependent proteoglycan degradation. Within 48 hours, these cellular responses resulted in NP tissue with only 25% of its original proteoglycan content. Conclusions. Because low levels of TNF-&agr;, comparable to those present physiologically, induced NP tissue degradation, this suggests that TNF-&agr; may contribute to the degenerative changes that occur in disc disease.

Initial results of a trial of preoperative external-beam radiation therapy and postoperative brachytherapy for retroperitoneal sarcoma

BackgroundSurgical resection alone does not cure the majority of patients with retroperitoneal sarcoma (RPS). We evaluated the effects of preoperative external-beam radiotherapy (XRT) and postoperative brachytherapy (BT) combined with complete surgical resection.MethodsFifty-five patients with primary or locally recurrent RPS judged to be resectable were entered onto a trial of combined therapy and observed prospectively. Forty-six patients underwent complete gross resection with curative intent. Of these, 41 patients completed preoperative XRT and 23 patients received BT. Outcome measures were treatment toxicity, overall survival, and disease-free survival (DFS).ResultsPreoperative XRT was very well tolerated and was associated with Radiation Therapy Oncology Group acute toxicity scores of ≤2 in all patients. Acute postoperative and BT-related toxicity resulted in modified RTOG scores of ≥3 in 39.1% (18 of 46) of patients. Late toxicity was associated with death in 4.3% (2 of 46) and with life-threatening illness in 2.2% (1 of 46) of patients, all of whom had been treated with BT to the upper abdomen. The 2-year overall survival and DFS for resected RPS were 88% and 80%, respectively. Significantly better 2-year DFS was achieved in patients with primary RPS and in those with low-grade tumors (93% and 95%, respectively).ConclusionsThe initial results of combined therapy are promising. Although preoperative XRT was very well tolerated, BT to the upper abdomen was associated with substantial toxicity. Our current protocol includes selective application of BT to the lower abdomen only.

Long-term intermittent shear deformation improves the quality of cartilaginous tissue formed in vitro

The formation of cartilaginous tissue in vitro is a promising alternative to repair damaged articular cartilage. However, recent attempts to tissue‐engineer articular cartilage that has similar properties to the native tissue have proven to be difficult. The in vitro‐formed cartilaginous tissue typically has a similar proteoglycan content to native cartilage, but has a reduced collagen content and only a fraction of the mechanical properties. In this study, we investigated whether the intermittent application of cyclic shearing forces during tissue formation would improve the tissue quality. Chondrocyte cultures were stimulated at a 2% shear strain amplitude at a frequency of 1 Hz for 400 cycles every 2nd day. At one week, both collagen and proteoglycan synthesis increased (23 ± 6% and 20 ± 6%, respectively) over the unstimulated, static controls. At four weeks, an increased amount of tissue formed (stimulated: 1.85 ± 0.08, unstimulated: 1.58 ± 0.07 mg dry wt.). This tissue contained approximately 40% more collagen (stimulated: 511 ± 23, unstimulated: 367 ± 24 μg/construct) and 35% more proteoglycans (stimulated: 376 ± 21, unstimulated: 279 ± 26 μg/construct). Tissues that formed in the presence of shearing forces also displayed a 3‐fold increase in compressive load‐bearing capacity (stimulated: 16 ± 5, unstimulated: 5 ± 1 kPa max. equilibrium stress) and a 6‐fold increase in stiffness (stimulated: 112 ± 36, unstimulated: 20 ± 6 kPa max. equilibrium modulus) compared to the static controls. These results demonstrate that intermittent application of dynamic shearing forces over a four‐week period improves the quality of cartilaginous tissue formed in vitro. Interestingly, low amplitudes of shear stimulation for short periods of time (6 min of stimulation applied every 2nd day) produced these changes.

Porous calcium polyphosphate scaffolds for bone substitute applications in vivo studies

Porous rods (6 mm in length and 4 mm in diameter) of calcium polyphosphate (CPP) made by gravity sintering of particles in the size ranges of 45-105, 105-150. and 150-250 microm and with initial volume percent porosity in the range of 35-45% were implanted in the distal femur of New Zealand white rabbits. In an initial experiment, four rabbits implanted with rods made from coarse particles (150-250 microm) were sacrificed at each of the following time points: 2 days, 2 weeks, 6 weeks and 12 weeks. In a subsequent experiment, 10 rabbits were implanted with rods made by sintering 45-105 microm particles and another 10 were made by using particles of 105-150 microm. These rabbits were sacrificed at 6 weeks (five rabbits) and 1 year (five rabbits). No adverse reaction was found histologically at any time point in either experiment. These experiments show that CPP macroporous rods can support bone ingrowth and that between 12 weeks and 1 year, the amount of bones formed is equivalent to the natural bone volume found at similar sites. The degradation of the CPP material is inversely proportional to the original particle size and is rapid initially (within the first 6 weeks) and slows down thereafter. In conclusion, this material seems to promote rapid bone ingrowth and can be tailored to degrade at a given rate in vivo to some degree through appropriate selection of the starting particle size.

Effect of Biomechanical Conditioning on Cartilaginous Tissue Formation in Vitro

Background: Although tissue engineering of articular cartilage is a promising approach for cartilage repair, it has been difficult to develop cartilaginous tissue in vitro that mimics the properties of native cartilage. Isolated chondrocytes grown in culture typically do not accumulate enough extracellular matrix, and the generated tissue possesses only a fraction of the mechanical properties of native cartilage. One potential explanation for this might be that the cells are grown in an environment that lacks the mechanical stimuli to which the chondrocytes are exposed in vivo. In this study, we compared the long-term effects of both dynamic compressive and shearing forces on cartilaginous tissue formation in vitro.Methods: Bovine articular chondrocytes were grown on the surface of porous ceramic substrates and were maintained under static, free-swelling conditions for a period of four weeks. Cultures were then subjected to six minutes of mechanical stimulation every other day, in either compression or shear, for an additional four-week period.Results: Cartilaginous tissues cultured in the presence of intermittent compression or shear were significantly thicker (p < 0.05) and had accumulated more extracellular matrix (p < 0.01) compared with the unstimulated controls. However, when normalized by the wet weight of the tissue, cultures stimulated in the presence of shearing forces contained more proteoglycans and collagen compared with compression-stimulated cultures. These cultures also displayed the largest increase in mechanical properties, with a threefold increase in equilibrium stress and a fivefold increase in equilibrium modulus.Conclusions and Clinical Relevance: The results of this study demonstrate that a brief application of mechanical forces applied periodically over a long duration can improve the quality of cartilaginous tissue formed in vitro. However, the changes in tissue composition and mechanical properties were dependent on the specific mode of the applied mechanical forces, with shear stimulation eliciting the greater effect. This finding suggests that chondrocytes may respond differently to different modes of applied forces.