Combined-modality treatment of localized soft tissue sarcomas of the extremities

Malignant peripheral nerve sheath tumor: models, biology, and translation

Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive, invasive cancer that comprise around 10% of all soft tissue sarcomas and develop in about 8-13% of patients with Neurofibromatosis Type 1. They are associated with poor prognosis and are the leading cause of mortality in NF1 patients. MPNSTs can also develop sporadically or following exposure to radiation. There is currently no effective targeted therapy to treat MPNSTs and surgical removal remains the mainstay treatment. Unfortunately, surgery is not always possible due to the size and location of the tumor, thus, a better understanding of MPNST initiation and development is required to design novel therapeutics. Here, we provide an overview of MPNST biology and genetics, discuss findings regarding the developmental origin of MPNST, and summarize the various model systems employed to study MPNST. Finally, we discuss current management strategies for MPNST, as well as recent developments in translating basic research findings into potential therapies.

Use of patient derived orthotopic xenograft models for real-time therapy guidance in a pediatric sporadic malignant peripheral nerve sheath tumor

Background:

The aim of this study was to test the feasibility and utility of developing patient-derived orthotopic xenograft (PDOX) models for patients with malignant peripheral nerve sheath tumors (MPNSTs) to aid therapeutic interventions in real time.

Patient & Methods:

A sporadic relapsed MPNST developed in a 14-year-old boy was engrafted in mice, generating a PDOX model for use in co-clinical trials after informed consent. SNP-array and exome sequencing was performed on the relapsed tumor. Genomics, drug availability, and published literature guided PDOX treatments.

Results:

A MPNST PDOX model was generated and expanded. Analysis of the patient’s relapsed tumor revealed mutations in the MAPK1, EED, and CDK2NA/B genes. First, the PDOX model was treated with the same therapeutic regimen as received by the patient (everolimus and trametinib); after observing partial response, tumors were left to regrow. Regrown tumors were treated based on mutations (palbociclib and JQ1), drug availability, and published literature (nab-paclitaxel; bevacizumab; sorafenib plus doxorubicin; and gemcitabine plus docetaxel). The patient had a lung metastatic relapse and was treated according to PDOX results, first with nab-paclitaxel, second with sorafenib plus doxorubicin after progression, although a complete response was not achieved and multiple metastasectomies were performed. The patient is currently disease free 46 months after first relapse.

Conclusion:

Our results indicate the feasibility of generating MPNST-PDOX and genomic characterization to guide treatment in real time. Although the treatment responses observed in our model did not fully recapitulate the patient’s response, this pilot study identify key aspects to improve our co-clinical testing approach in real time.

Establishment and characterization of patient-derived cancer models of malignant peripheral nerve sheath tumors

Background

Malignant peripheral nerve sheath tumors (MPNSTs) are a rare subtype of soft-tissue sarcoma, derived from a peripheral branch or the sheath of the sciatic nerve, brachial plexus, or sacral plexus. The clinical outcomes for MPNST patients with unresectable or metastatic tumors are dismal, and novel therapeutic strategies are required. Although patient-derived cancer cell lines are vital for basic research and preclinical studies, few MPNST cell lines are available from public cell banks. Therefore, the aim of this study was to establish cancer cell lines derived from MPNST patients.

Methods

We used tumor tissues from five patients with MPNSTs, including one derived from a rare bone tissue MPNST. The tumor tissues were obtained at the time of surgery and were immediately processed to establish cell lines. A patient-derived xenograft was also established when a sufficient amount of tumor tissue was available. The characterization of established cells was performed with respect to cell proliferation, spheroid formation, and invasion. The mutation status of actionable genes was monitored by NCC Oncopanel, by which the mutation of 114 genes was assessed by next-generation sequencing. The response to anti-cancer agents, including anti-cancer drugs approved for the treatment of other malignancies was investigated in the established cell lines.

Results

We established five cell lines (NCC-MPNST1-C1, NCC-MPNST2-C1, NCC-MPNST3-C1, NCC-MPNST4-C1, and NCC-MPNST5-C1) from the original tumors, and also established patient-derived xenografts (PDXs) from which one cell line (NCC-MPNST3-X2-C1) was produced. The established MPNST cell lines proliferated continuously and formed spheroids while exhibiting distinct invasion abilities. The cell lines had typical mutations in the actionable genes, and the mutation profiles differed among the cell lines. The responsiveness to examined anti-cancer agents differed among cell lines; while the presence of an actionable gene mutation did not correspond with the response to the anticipated anti-cancer agents.

Conclusion

The established cell lines exhibit various characteristics, including proliferation and invasion potential. In addition, they had different mutation profiles and response to the anti-cancer agents. These observations suggest that the established cell lines will be useful for future research on MPNSTs.

Targeting Refractory Sarcomas and Malignant Peripheral Nerve Sheath Tumors in a Phase I/II Study of Sirolimus in Combination with Ganetespib (SARC023)

Purpose

Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive soft tissue sarcomas. Combining Hsp90 inhibitors to enhance endoplasmic reticulum stress with mTOR inhibition results in dramatic MPNST shrinkage in a genetically engineered MPNST mouse model. Ganetespib is an injectable potent small molecule inhibitor of Hsp90. Sirolimus is an oral mTOR inhibitor. We sought to determine the safety, tolerability, and recommended dose of ganetespib and sirolimus in patients with refractory sarcomas and assess clinical benefits in patients with unresectable/refractory MPNSTs. Patients and Methods. In this multi-institutional, open-label, phase 1/2 study of ganetespib and sirolimus, patients ≥16 years with histologically confirmed refractory sarcoma (phase 1) or MPNST (phase 2) were eligible. A conventional 3 + 3 dose escalation design was used for phase 1. Pharmacokinetic and pharmacodynamic measures were evaluated. Primary objectives of phase 2 were to determine the clinical benefit rate (CBR) of this combination in MPNSTs. Patient-reported outcomes assessed pain.

Results

Twenty patients were enrolled (10 per phase). Toxicities were manageable; most frequent non-DLTs were diarrhea, elevated liver transaminases, and fatigue. The recommended dose of ganetespib was 200 mg/m² intravenously on days 1, 8, and 15 with sirolimus 4 mg orally once daily with day 1 loading dose of 12 mg. In phase 1, one patient with leiomyosarcoma achieved a sustained partial response. In phase 2, no responses were observed. The median number of cycles treated was 2 (1–4). Patients did not meet the criteria for clinical benefit as defined per protocol. Pain ratings decreased or were stable.

Conclusion

Despite promising preclinical rationale and tolerability of the combination therapy, no responses were observed, and the study did not meet parameters for further evaluation in MPNSTs. This trial was registered with (NCT02008877).

Targeting IL-13Rα2 for effective treatment of malignant peripheral nerve sheath tumors in mouse models

OBJECTIVE

Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive soft tissue sarcomas that harbor a high potential for metastasis and have a devastating prognosis. Combination chemoradiation aids in tumor control and decreases tumor recurrence but causes deleterious side effects and does not extend long-term survival. An effective treatment with limited toxicity and enhanced efficacy is critical for patients suffering from MPNSTs.

METHODS

The authors recently identified that interleukin-13 receptor alpha 2 (IL-13Rα2) is overexpressed on MPNSTs and could serve as a precision-based target for delivery of chemotherapeutic agents. In the work reported here, a recombinant fusion molecule consisting of a mutant human IL-13 targeting moiety and a point mutant variant of Pseudomonas exotoxin A (IL-13.E13 K-PE4E) was utilized to treat MPNST in vitro in cell culture and in an in vivo murine model.

RESULTS

IL-13.E13 K-PE4E had a potent cytotoxic effect on MPNST cells in vitro. Furthermore, intratumoral administration of IL-13.E13 K-PE4E to orthotopically implanted MPNSTs decreased tumor burden 6-fold and 11-fold in late-stage and early-stage MPNST models, respectively. IL-13.E13 K-PE4E treatment also increased survival by 23 days in the early-stage MPNST model.

CONCLUSIONS

The current MPNST treatment paradigm consists of 3 prongs: surgery, chemotherapy, and radiation, none of which, either singly or in combination, are curative or extend survival to a clinically meaningful degree. The results presented here provide the possibility of intratumoral therapy with a potent and highly tumor-specific cytotoxin as a fourth treatment prong with the potential to yield improved outcomes in patients with MPNSTs.

MLN8237 treatment in an orthoxenograft murine model for malignant peripheral nerve sheath tumors

OBJECTIVE

Malignant peripheral nerve sheath tumors (MPNSTs) are soft-tissue sarcomas arising from peripheral nerves. MPNSTs have increased expression of the oncogene aurora kinase A, leading to enhanced cellular proliferation. This makes them extremely aggressive with high potential for metastasis and a devastating prognosis; 5-year survival estimates range from a dismal 15% to 60%. MPNSTs are currently treated with resection (sometimes requiring limb amputation) in combination with chemoradiation, both of which demonstrate limited effectiveness. The authors present the results of immunohistochemical, in vitro, and in vivo analyses of MLN8237 for the treatment of MPNSTs in an orthoxenograft murine model.

METHODS

Immunohistochemistry was performed on tumor sections to confirm the increased expression of aurora kinase A. Cytotoxicity analysis was then performed on an MPNST cell line (STS26T) to assess the efficacy of MLN8237 in vitro. A murine orthoxenograft MPNST model transfected to express luciferase was then developed to assess the efficacy of aurora kinase A inhibition in the treatment of MPNSTs in vivo. Mice with confirmed tumor on in vivo imaging were divided into 3 groups: 1) controls, 2) mice treated with MLN8237, and 3) mice treated with doxorubicin/ifosfamide. Treatment was carried out for 32 days, with imaging performed at weekly intervals until postinjection day 42. Average bioluminescence among groups was compared at weekly intervals using 1-way ANOVA. A survival analysis was performed using Kaplan-Meier curves.

RESULTS

Immunohistochemical analysis showed robust expression of aurora kinase A in tumor cells. Cytotoxicity analysis revealed STS26T susceptibility to MLN8237 in vitro. The group receiving treatment with MLN8237 showed a statistically significant difference in tumor size compared with the control group starting at postinjection day 21 and persisting until the end of the study. The MLN8237 group also showed decreased tumor size compared with the doxorubicin/ifosfamide group at the conclusion of the study (p = 0.036). Survival analysis revealed a significantly increased median survival in the MLN8237 group (83 days) compared with both the control (64 days) and doxorubicin/ifosfamide (67 days) groups. A hazard ratio comparing the 2 treatment groups showed a decreased hazard rate in the MLN8237 group compared with the doxorubicin/ifosfamide group (HR 2.945; p = 0.0134).

CONCLUSIONS

The results of this study demonstrate that MLN8237 is superior to combination treatment with doxorubicin/ifosfamide in a preclinical orthoxenograft murine model. These data have major implications for the future of MPNST research by providing a robust murine model as well as providing evidence that MLN8237 may be an effective treatment for MPNSTs.

Diagnosis, Classification, and Management of Soft Tissue Sarcomas

BACKGROUND

Soft tissue sarcomas are challenging to oncologists due to their unique character, the infrequency of their occurrence, and the difficulties in predicting outcomes. Advances in imaging, as well as improvements in surgical techniques and adjunctive treatment methods, have improved care for patients with these unusual disorders.

METHODS

The various types of soft tissue tumors are defined, and the statistics for the Orthopaedic Oncology Group in relation to them are reviewed and compared with literature references.

RESULTS

The overall survival rate for 1,220 tumors treated at our institute from June 1972 to June of 2001 was 72%, with a wide range. Patients with leiomyosarcomas, clear cell sarcomas, and malignant fibrous histiocytomas had a poorer survival rate, while those with fibrosarcomas, liposarcomas, and neurofibrosarcomas fared better. Outcome was affected by patient age, tumor anatomic site, tumor stage, and a history of recurrence.

CONCLUSIONS

Competent imaging, predictive immunological and genetic studies, improved surgery, and newer methods of adjunctive and neoadjunctive treatment should result in improvements in outcomes for patients with these tumors.

The promise of signal transduction in genetically driven sarcomas of the nerve

Neurofibromatosis type 1 (NF1) is an autosomal dominant tumor predisposition syndrome. Malignant peripheral nerve sheath tumors (MPNST) are aggressive soft tissue sarcomas arising from peripheral nerve sheaths, and the most commonly lethal feature associated with NF1. The hallmark of NF1 and NF1-related MPNST is the loss of neurofibromin expression. Loss of neurofibromin is considered a tumor-promoting event, and leads to constitutive activation of RAS and its downstream effectors. However, RAS activation alone is not sufficient for MPNST formation, and additional tumor suppressors and signaling pathways have been implicated in tumorigenesis of MPNST. Taking advantage of the rapid development of novel therapeutics targeting key molecular pathways across all cancer types, the best-in-class modulators of these pathways can be assessed in pre-clinical models and translated into clinical trials for patients with MPNST. Here, we describe the genetic changes and molecular pathways that drive MPNST formation and highlight the promise of signal transduction to identify therapies that may treat these tumors more effectively.

Malignant Peripheral Nerve Sheath Tumors State of the Science: Leveraging Clinical and Biological Insights into Effective Therapies

Malignant peripheral nerve sheath tumor (MPNST) is the leading cause of mortality in patients with neurofibromatosis type 1. In 2002, an MPNST consensus statement reviewed the current knowledge and provided guidance for the diagnosis and management of MPNST. Although the improvement in clinical outcome has not changed, substantial progress has been made in understanding the natural history and biology of MPNST through imaging and genomic advances since 2002. Genetically engineered mouse models that develop MPNST spontaneously have greatly facilitated preclinical evaluation of novel drugs for translation into clinical trials led by consortia efforts. Continued work in identifying alterations that contribute to the transformation, progression, and metastasis of MPNST coupled with longitudinal follow-up, biobanking, and data sharing is needed to develop prognostic biomarkers and effective prevention and therapeutic strategies for MPNST.

Uric acid levels in blood are associated with clinical outcome in soft-tissue sarcoma patients

BACKGROUND

Recent evidence indicates toward a role of uric acid (UA) as a potential antioxidant. Elevated UA levels were shown to be associated with better survival in various malignancies. The aim of the present study was to evaluate the prognostic relevance of pre-operative UA levels on cancer-specific survival (CSS) in soft-tissue sarcoma (STS) patients who underwent curative surgical resection.

METHODS

Three hundred and fifty-seven patients with STS were included in the study. Pre-operative serum UA level was measured using an enzymatic colorimetric assay. The effect of UA levels on CSS was analyzed using Kaplan-Meier curves. To further evaluate the prognostic impact of UA levels, univariate and multivariate Cox proportional models were calculated.

RESULTS

Among the 357 STS patients, cancer-related deaths occurred in 20 (24.7%) of 81 patients with a serum UA level <279.6 µmol/L and in 36 (13%) of 276 patients with a UA level ≥279.6 µmol/L. In univariate analysis, elevated UA levels were significantly associated with increased CSS in STS patients [hazard ratio (HR) 0.44, 95% confidence interval (CI) 0.26-0.77, p=0.004]. Furthermore, elevated UA levels remain a significant factor for better CCS in multivariate analysis (HR 0.42, 95% CI 0.23-0.75, p=0.003).

CONCLUSIONS

Our study is the first one to demonstrate that higher UA levels are associated with positive clinical outcome in STS patients. UA levels are a simple and cost-effective test for the assessment of the prognosis of STS patients.

Current treatment options for malignant peripheral nerve sheath tumors

Malignant peripheral nerve sheath tumors (MPNST) are aggressive soft tissue sarcomas characterized by high risk of local recurrence and distant metastasis. The only known curative therapy is complete resection. Adjuvant radiation is recommended for larger lesions or those with more aggressive histology. Given the dismal prognosis in tumors that cannot be cured by surgery alone and the lack of systemic therapy with proven benefit, targeted therapies based on knowledge of activation of the Ras pathway and downstream effectors have been trialed in MPNST, thus far without proven benefit. However, novel or combination therapies based on recent preclinical advances are highly desirable and are the subject of ongoing clinical trials.

Prognostic factors in adult soft tissue sarcoma treated with surgery combined with radiotherapy: a retrospective single-center study on 164 patients

The aim of the present study is to assess the disease profile, outcome and prognostic factors in patients treated with surgery combined with radiotherapy (RT), with or without chemotherapy (CXT), for soft-tissue sarcoma (STS) in a multidisciplinary setting. One hundred and sixty-four patients with STS treated between 1980 and 2010 at the Centre Hospitalier Universitaire Vaudois were enrolled in this retrospective study. Seventy-six percent of patients underwent postoperative RT with (24%), or without (52%) CXT, 15% preoperative RT with (5%), or without (10%) CXT, surgery alone (7%), or RT alone (2%) with or without CXT. The median follow-up was 60 months (range 6-292). Local failure was observed in 18%, and distant failure in 21% of the patients. Overall survival (OS), diseasefree survival (DFS), local control (LC) and distant metastases-free survival (DMFS) were 88%, 68%, 83%, and 79% at 5 years, and 80%, 56%, 76%, and 69% at 10 years, respectively. In univariate analyses, favorable prognostic factors for OS, DFS, and DMFS were tumor size 6 cm or less, World Health Organization (WHO)/Zubrod score 0, and stage 2 or less. Age and superficial tumors were favorable only for OS and DMFS respectively. STS involving the extremities had a better outcome regarding DFS and LC. Histological grade 2 or less was favorable for DFS, DMFS, and LC. Radical surgery was associated with better LC and DMFS. RT dose more than 60 Gy was favorable for OS, DFS, and LC. In multivariate analyses, independent factors were age for OS; tumor size for OS, DFS and DMFS; WHO/Zubrod score for OS, DFS and LC; hemoglobin level for DFS; site for DFS and LC; tumor depth for DMFS; histological grade for DFS and LC; surgical procedure for LC and DMFS; and RT dose for OS. This study confirms that in a multidisciplinary setting, STS have a fairly good prognosis. A number of prognostic and predictive factors, including the role of surgery combined with RT, were identified. Regarding RT, a dose of more than 60 Gy was associated with a better outcome, at the price of a higher toxicity. We could not demonstrate a superiority of preoperative RT over postoperative RT.

Malignant peripheral nerve sheath tumors in Africa: a clinicopathological study

Introduction. Malignant peripheral nerve sheath tumors (MPNSTs) are rare, aggressive soft tissue sarcomas associated with poor prognosis, that most commonly affect patients aged 20 to 50 years, but have also been reported in children. There is little reported in literature on these tumors in Africa. Materials and Methods. A search of the hospital pathology database between 1992 and 2008 revealed 333 nerve sheath tumors, of which 31 were MPNSTs. Four representative case reports are presented. Discussion. MNPSTs have rarely been reported from sub-Saharan Africa; in this study, they constituted 9.3% of all nerve sheath tumors. The trunk (42%) and limbs (45%) were the most frequently affected anatomical sites. Late presentation of malignant lesions in this environment is exemplified by the four case presentations patients. Conclusions. This report confirms observations from studies on MPNSTs from other environments. Anatomically centrally located MPNSTs may have a higher incidence in sub-Saharan Africa than in the West. Because NF1-associated MPNSTs are difficult to diagnose clinically, and because surgery is the only mode of therapy that offers a complete cure, a lifetime follow-up is important, as this would enable diagnosis of early lesions amenable to surgical extirpation.

Recurrence patterns and survival for patients with intermediate- and high-grade myxofibrosarcoma

PURPOSE

Myxofibrosarcoma (MFS) is a rare sarcoma with a predilection for multiple local recurrences (LR), for which optimal treatment has not been defined. We reviewed our experience to determine the impact of surgery and radiation therapy (RT) on pattern of recurrence, limb salvage, and overall survival (OS).

METHODS AND MATERIALS

Between 1995 and 2005, 36 patients with localized intermediate- or high-grade MFS were treated at our institution. Data on clinicopathologic features, treatments, and patient outcomes were reviewed and analyzed.

RESULTS

Median age was 72.5 years (range, 42-96 years). Median tumor size was 7.5 cm, and 34 tumors (94%) were high grade. All patients underwent surgery at our institution, including re-resections in 20 patients (56%) after initial surgery elsewhere. Margins were microscopically positive in 9 patients (25%). RT was given to 28 patients (78%) pre - and/or postoperatively. After a median follow-up of 3.5 years (range, 0.4-12.4 years), 11 patients (31%) developed LR. There were no significant predictors for LR on univariate analysis, including margin status or use of RT. Limb salvage was ultimately achieved in only 5 of 11 LRs (45%) because of multiple subsequent LRs. Distant recurrence (DR) occurred in 6 patients (17%). Median and 4-year OS were 96 months and 65%, respectively. Seven patients (19%) died of tumor-related causes, 6 of whom had DRs. On univariate analysis, tumor size was associated with OS.

CONCLUSIONS

Despite aggressive surgery and RT, intermediate- and high-grade MFS are associated with a high rate of LR that adversely affects limb preservation. More aggressive local treatment strategies are necessary.

Current status of sporadic and neurofibromatosis type 1-associated malignant peripheral nerve sheath tumors

Malignant peripheral nerve sheath tumors (MPNSTs) are highly aggressive soft tissue sarcomas that rarely occur in the general population but have a lifetime incidence of 8% to 13% in those with neurofibromatosis type 1 (NF1). Complete surgical resection is the standard treatment for MPNSTs. Unresectable MPNSTs carry a poor prognosis, and survival appears to be worse in NF1-associated tumors than in sporadic tumors. The response rate of MPNSTs to standard chemotherapeutic agents used to treat pediatric and adult soft tissue sarcomas is unknown and is currently undergoing evaluation in a multi-institutional clinical trial. With an increasing understanding of the molecular pathogenesis of MPNSTs, clinical trials with targeted agents have become available and have established that histology-specific trials in this rare malignancy are feasible. This knowledge, coupled with the availability of preclinical MPNST models, likely will accelerate the development of effective treatments for this malignancy.

The vertical and extended rectus abdominis myocutaneous flap for irradiated thigh and groin defects

BACKGROUND

Thigh and groin tumors are often treated with limb-sparing surgery and adjuvant preoperative irradiation, frequently resulting in complex soft-tissue defects and wounds. The authors evaluated outcomes after reconstruction of these difficult wounds with the vertical and extended rectus abdominis myocutaneous (RAM) flap.

METHODS

A retrospective chart review was performed of 50 consecutive patients who underwent inferiorly based RAM pedicle flaps to reconstruct thigh and groin defects after preoperative irradiation and oncologic resection. Timing of reconstruction, flap design, complications, metastasis/recurrence, and ambulation status were analyzed.

RESULTS

Fifty patients (mean age, 56 years; range, 10 to 83 years) underwent 51 RAM flaps. Sixty-three percent of flaps were for immediate reconstruction and the remaining flaps were for secondary coverage after failure of initial closure. There were no perioperative deaths. The median length of hospital stay was 9 days. All flaps survived. The vertical RAM flap was used in 63 percent of cases; the extended RAM flap was used in 37 percent and permitted closure of larger, contralateral, and more distal defects. With a mean follow-up of 28 months, complications included partial flap necrosis [n = 2 (4 percent)], infection [n = 8 (16 percent)], seroma [n = 2 (4 percent)], dehiscence [n = 2 (4 percent)], and donor-site bulge [n = 6 (12 percent)]. Postoperative wound complications were significantly higher in patients who underwent delayed or secondary (47 percent) versus immediate reconstruction (9.4 percent, p < 0.005). Three patients required additional coverage. There was no significant difference in flap complications between the extended and nonextended flap designs. Independent ambulation was achieved in 82 percent of patients.

CONCLUSIONS

The vertical and extended RAM flaps provide reliable coverage of irradiated thigh and groin oncologic wounds, with significantly improved results obtained with immediate versus delayed reconstruction.

Relation between pO2, 31P magnetic resonance spectroscopy parameters and treatment outcome in patients with high-grade soft tissue sarcomas treated with thermoradiotherapy

PURPOSE

In a prior study, the combination of (31)P magnetic resonance spectroscopy (MRS)-based intracellular pH (pHi) and T2 relaxation time was highly predictive of the pathologic complete response (pCR) rate in a small series of patients with soft tissue sarcomas (STSs) treated with thermoradiotherapy. Changes in the magnetic resonance metabolite ratios and pO(2) were related to the pCR rate. Hypoxia also correlated with a greater likelihood for the development of metastases. Because of the limited number of patients in the prior series, we initiated this study to determine whether the prior observations were repeatable and whether (31)P MRS lipid-related resonances were related to a propensity for metastasis.

METHODS AND MATERIALS

Patients with high-grade STSs were enrolled in an institutional review board-approved Phase II thermoradiotherapy trial. All tumors received daily external beam radiotherapy (1.8-2.0 Gy, five times weekly) to a total dose of 30-50 Gy. Hyperthermia followed radiotherapy by <1 h and was given two times weekly. Tumors were resected 4-6 weeks after radiotherapy completion. The MRS/MRI parameters included (31)P metabolite ratios, pHi, and T2 relaxation time. The median pO(2) and hypoxic fraction were determined using pO(2) histography. Comparisons between experimental endpoints and the pCR rate and metastasis-free and overall survival were made.

RESULTS

Of 35 patients, 21 and 28 had reportable pretreatment MRS/MRI and pO(2) data, respectively. The cutpoints for a previously tested receiver operating curve for a pCR were T2 = 100 and pHi = 7.3. In the current series, few tumors fell below the cutpoints so validation was not possible. The phosphodiester (PDE)/inorganic phosphate (Pi) ratio and hypoxic fraction correlated inversely with the pCR rate in the current series (Spearman correlation coefficient -0.51, p = 0.017; odds ratio of percentage of necrosis > or =95% = 0.01 for a 1% increase in the hypoxic fraction; Wald p = 0.036). The pretreatment phosphomonoester (PME)/Pi ratio also correlated inversely with the pCR rate (odds ratio of percentage of necrosis > or =95% = 0.06 for pretreatment PME/Pi ratio >0.8 vs. < or =0.8, Wald p = 0.023). The pretreatment PME/PDE ratio correlated strongly with metastasis-free survival and overall survival (p = 0.012 and hazard ratio = 5.8, and p = 0.038 and hazard ratio = 6.75, respectively).

CONCLUSION

The dual parameter model containing pHi and T2 to predict the pCR in STSs treated with thermoradiotherapy was not verified. However, other parameters were statistically significant, including the PDE/Pi ratio and hypoxic fraction. These relationships may have interfered with our ability to obtain the pCR rate predicted by thermal doses achieved in these patients. The relationship between the PME/PDE ratio and metastasis-free and overall survival was provocative, but requires additional study to verify its predictive capability. Currently, 50% of all STS patients with high-grade tumors develop distant metastasis even when excellent local control is achieved. Parameters that could help select for patients who need adjuvant chemotherapy could have significant clinical benefit.