Current concepts in the evaluation and treatment of osteosarcoma

Giant cell-rich osteosarcoma: A match pair analysis of 11 new cases and literature review of 56 patients

BACKGROUND

Limited remains known on giant cell-rich osteosarcoma (GCRO) with current studies being case reports or smaller series. This investigation compared GCRO and conventional osteoblastic osteosarcoma (OOS) with regard to demographics and survival.

METHODS

An institutional tumor registry was used to identify 11 patients (six males) treated for GCRO. Mean age was 43 years. Staging showed American Joint Committee on Cancer (AJCC) stages IIA in four and IIB in seven patients. Mean follow-up was 14 years. Study initiatives were: (1) Comparison of demographics between GCRO and 167 OOS from our institutional registry, (2) Differences in survival between GCRO and 33 OOS case controls (based on sex and AJCC stage), as well as 10 OOS using an age-based propensity match, and (3) Summary of all GCRO cases reported in the literature.

RESULTS

(1) Sex (p = 0.53), grading (p = 0.56), AJCC stage (p = 0.42), and chemotherapeutic response rate (p = 0.67) did not differ between groups. Age was significantly increased in GCRO (p = 0.001). (2) Case-control and propensity-matched groups revealed no difference in disease-free survival, local recurrence, and distant disease-free survival at 2 years (p > 0.05). (3) Mean age of 56 patients (50% males) reported in the literature was 26 years. After merging with our 11 cases, the 2-year disease-free survival was 66%.

CONCLUSIONS

GCRO remains a rare disease with high short-term mortality. Although affecting older patients more than conventional osteosarcoma, GCRO should not be viewed as a predictor of survival compared to OOS.

Osteosarcoma

Osteosarcoma is the most common primary malignant tumour of the bone. Osteosarcoma incidence is bimodal, peaking at 18 and 60 years of age, and is slightly more common in males. The key pathophysiological mechanism involves several possible genetic drivers of disease linked to bone formation, causing malignant progression and metastasis. While there have been significant improvements in the outcome of patients with localized disease, with event-free survival outcomes exceeding 60%, in patients with metastatic disease, event-free survival outcomes remain poor at less than 30%. The suspicion of osteosarcoma based on radiographs still requires pathological evaluation of a bone biopsy specimen for definitive diagnosis and CT imaging of the chest should be performed to identify lung nodules. So far, population-based screening and surveillance strategies have not been implemented due to the rarity of osteosarcoma and the lack of reliable markers. Current screening focuses only on groups at high risk such as patients with genetic cancer predisposition syndromes. Management of osteosarcoma requires a multidisciplinary team of paediatric and medical oncologists, orthopaedic and general surgeons, pathologists, radiologists and specialist nurses. Survivors of osteosarcoma require specialized medical follow-up, as curative treatment consisting of chemotherapy and surgery has long-term adverse effects, which also affect the quality of life of patients. The development of osteosarcoma model systems and related research as well as the evaluation of new treatment approaches are ongoing to improve disease outcomes, especially for patients with metastases.

Do Not Miss the Tumor: A Novel Presentation of Osteosarcoma

Antalgic gait is a common clinical presentation among pediatric patients and can have many different etiologies, with rare life-threatening etiologies including primary bone malignancies. Osteosarcoma is the most common primary malignancy of bone in pediatric and adolescent patients. The incidence rate of osteosarcoma has been reported as high as 5 to 7 per million among patients 19 years old or younger with males slightly more affected than females and African-Americans more than other racial groups. This report describes the case of a five-year-old African-American female who presented with an antalgic gait secondary to osteosarcoma in the left distal femur and follows her through treatment. In this case, the age is atypical as the peak incidence for osteosarcoma is around 16 years of age and is postulated to coincide with growth spurts. Osteosarcoma can have a range of presentations making it difficult to diagnose, which can cause delays in treatment and potential poor patient outcomes. Due to this, such a diagnosis must be included in the differential for patients presenting with antalgic gait. Because primary-care physicians and pediatricians may be the first medical providers to encounter patients with osteosarcoma, it is imperative that such clinicians are familiar with the signs and symptoms associated with osteosarcomas in order to reduce the risk of metastasis and disease progression and prevent treatment delays. Additionally, we believe these clinicians should have a low threshold to refer patients to orthopedists or oncologic specialists in the cases of persistent pain or inconsistencies with history, physical exam, and diagnostic studies. Finally, direct communication and discussion between radiologists and referring clinicians helps decrease delays in diagnosing of osteosarcoma and other life-threatening conditions.

Rare Diseases of the Middle Ear and Lateral Skull Base

Otalgia, otorrhea and hearing loss are the most common ear-related symptoms that lead to the consultation of an otolaryngologist. Furthermore, balance disorders and affections of the cranial nerve function may play a role in the consultation. In large academic centres, but also in primary care, the identification of rare diseases of the middle ear and the lateral skull base is essential, as these diseases often require interdisciplinary approaches to establish the correct diagnosis and to initiate safe and adequate treatments. This review provides an overview of rare bone, neoplastic, haematological, autoimmunological and infectious disorders as well as malformations that may manifest in the middle ear and the lateral skull base. Knowledge of rare disorders is an essential factor ensuring the quality of patient care, in particular surgical procedures. Notably, in untypical, complicated, and prolonged disease courses, rare differential diagnoses need to be considered.

Recent Imaging Advancements for Lung Metastases in Children with Sarcoma

In children and adolescents affected by musculoskeletal sarcomas (both soft tissue and bone sarcomas), the presence of lung metastases is a frequent complication, that should be known since the patient's prognosis, as management, and treatment depend on it. During the staging phase, the detection of lung metastases should be sensitive and specific, and it should be carried out by minimizing the radiation exposure. To deal with this problem, imaging has reached important goals in recent years, thanks to the development of cone-beam CT or low-dose computed tomography, with some new iterative reconstruction methods, such as Veo and ASIR. Imaging is also fundamental for the possibility to perform lung biopsies under CT guidance, with less morbidity, less time-consumption, and shorter recovery time, compared to surgical biopsies.Moreover, important results have also been demonstrated in the treatment of lung metastases, due to the improvement of new mini-invasive image-guided percutaneous thermal ablation procedures, which proved to be safe and effective also in young patients.

An HIV-Positive Patient Presenting with Malignant Bone Tumor in Left Tibia Treated with Microwave Ablation for Limb Salvage

BACKGROUND

We report on a patient with human immunodeficiency virus (HIV)-positive disease with a malignant bone tumor in the left proximal tibia treated with surgery using microwave ablation (MWA).

CASE PRESENTATION

A 50-year-old Chinese male presented with sudden pain in the left knee and weight loss that had begun 2 months prior to his visit. The preoperative X-ray and MRI scan both demonstrated significant osteolytic destruction in the left proximal tibia surrounded with soft tissue mass. The patient underwent limb salvage surgery for his left leg with the technique of microwave ablation in situ. The pathology revealed myofibroblastic sarcoma with no positive margins, stage T2N0M0. The patient has a satisfactory functional and cosmetic limb with no evidence of disease at a follow-up time of 2 years.

CONCLUSION

MWA is a feasible and effective surgical method for the limb salvage operation, especially for the patient with poor immunological function, e.g., HIV infection. It might offer an innovative and distinctive therapeutic alternative for malignant bone tumors, while avoiding prosthesis replacement.

Popliteal lymph nodes in patients with osteosarcoma: are they metastatic?

PURPOSE

To evaluate the prevalence, imaging appearance, and significance of popliteal lymph nodes (PLN) on magnetic resonance imaging (MRI) in patients with distal femoral or proximal tibial osteosarcoma (OS).

METHOD AND MATERIALS

This study included consecutive patients with OS presenting from May 2016 to March 2018. Inclusion criteria were patients with distal femoral or proximal tibial OS with MRI and pathology at our institution. On MRI, two radiologists recorded primary tumor features (size, location, signal, extra-compartmental extension), and PLN characteristics (mean size, presence/absence of fatty hilum, mineralization, PET/bone scintigraphy avidity, contrast enhancement, and diffusion restriction). Tumor histology, stage, and clinical follow-up were recorded. Descriptive statistics were provided.

RESULTS

Sixteen patients with OS (age 20 ± 10 (range10-40) years, 10/16 male) were included. Although 81% (13/16) of the patients had PLNs at presentation (size range 0.3-3.6 cm), fewer patients had extra-compartmental spread: intra-articular extension 50% (8/16), skip lesions 19% (3/16), lung metastases 31% (5/16), and osseous metastases 12% (2/16). Four (25% (4/16)) patients had PLN ≥ 1 cm; two were histologically proven reactive. One was presumed metastatic due to rapid development, mineralization, and FDG-avidity on PET/CT. The other ≥ 1 cm PLNs along with all twelve (75% (12/16)) that were < 1 cm in mean diameter were presumed non-metastatic with documented stability for at least 12 months of follow-up.

CONCLUSION

PLNs are frequently visible on MRI in patients with OS but are rarely (prevalence = 6%) metastatic. Features on MRI which may suggest metastatic PLNs include large size > 1 cm and loss of a fatty hilum.

Malignant distal femur tumors management in children, low cost innovations with affordable care in a tertiary care hospital, a cross sectional study

INTRODUCTION

Malignant musculoskeletal tumors in children are mostly comprised of Osteosarcoma and Ewing's sarcoma and distal femur is the most common site for primary bone tumors. This study examined the surgical management outcomes of pediatric patients (<18 years) presented in our setup with malignant distal femur tumors.

METHODOLOGY

We retrospectively reviewed the medical records of patients diagnosed with malignant sarcomas of distal femur and younger than 18 years of age who underwent limb salvage surgery during June 2009-June2017.

RESULTS

There were 31 pediatric patients who had distal femur malignant tumors and out of them 20 patients were selected who underwent limb salvage as a primary surgery. The mean age (range) of patients was 11.90 (6-17) years. Seventeen had osteosarcoma and three had Ewing's sarcoma. In surgery all patients were offered reconstruction. Post-operative complications were observed in (50%) patients while other 50% patients had no complications. Wound infection, flap necrosis, broken plates with non-union and recurrence of disease were the reported complications. Revision surgery was performed in 10 patients out of 20 patients.

CONCLUSION

Salvage was the primary option in our surgery and revision surgery was performed in the cases due to complications. Small sample size was the limitation of the study.

Effectiveness of electrical stimulation for postoperative pain in patients with osteosarcoma: A systematic review protocol of clinical controlled trial

BACKGROUND

This study aims to investigate the effectiveness and safety of electrical stimulation (ES) for postoperative pain (PPP) in patients with osteosarcoma systematically.

METHODS

We will systematically search the following electronic databases from inception to the May 1, 2019: MEDILINE, Cochrane Library, EMBASE, Web of Science, Springer, and CNKI without language restrictions. All literatures of randomized controlled trials (RCTs) and case-controlled studies (CCSs) of ES for PPP in patients with osteosarcoma will be included. RevMan 5.3 software (Cochrane Community; London, UK) and STATA 15.0 software (StataCorp; College Station) will be used for statistical analysis. Cochrane risk of bias will be used for methodological quality assessment for RCTs and Newcastle-Ottawa Scale will be utilized for CCSs.

RESULTS

This study will assess the clinical effectiveness and safety of ES for PPP in patients with osteosarcoma through assessing primary outcome of pain intensity and secondary outcomes of frequency of rescue analgesic use, cumulative morphine consumption, quality of recovery, as well as adverse events.

CONCLUSION

This study will provide latest evidence on effectiveness and safety of ES for PPP in patients with osteosarcoma, and may also provide guidance for both clinician and further studies.

DISSEMINATION AND ETHICS

This study does not require ethical approval, because it will not analyze the individual patient data. Its results are expected to be published in peer-reviewed journals.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42019135790.

Establishing musculoskeletal oncology service in resource constrained country: challenges and solutions

The burden of orthopedic tumor surgery in Pakistan is not known. Similarly the number of procedures being performed for bone and soft tissue surgery are not known. This is even becoming more challenging where the existence of rules and regulations in health care are next to minimal. Furthermore data recording in our country and case registries hardly exist. Despite the lack of information and resources, with high disease burden on community, various providers provide surgical interventions every day in our settings. A lot of tumor surgery is still being done by general surgeons and general orthopedic surgeons who have little knowledge and update about musculoskeletal oncology principles. Lack of subspecialized centers and the high cost of such centers force the patients to visit these surgeons for a highly sophisticated problem like a bone tumor which is the disease of young bones. In this article we will emphasize on the difficulty in establishing an orthopedic tumor service in our part of the world and the consequences including delay in diagnosis, faulty course of management and later decline in functionality, disease progression and increased mortality. We will highlight the principles and stepwise approach of orthopedic tumor surgery and explain the difficulty encountered if these principles are not followed.

Molecular genetics of osteosarcoma

Osteosarcoma is the predominant form of bone cancer, affecting mostly adolescents. Recent progress made in molecular genetic studies of osteosarcoma has changed our view on the cause of the disease and ongoing therapeutic approaches for patients. As we draw closer to gaining more complete catalogs of candidate cancer driver genes in common forms of cancer, the landscape of somatic mutations in osteosarcoma is emerging from its first phase. In this review, we summarize recent whole genome and/or whole exome genomic studies, and then put these findings in the context of genetic hallmarks of somatic mutations and mutational processes in human osteosarcoma. One of the lessons learned here is that the extent of somatic mutations and complexity of the osteosarcoma genome are similar to that of common forms of adult cancer. Thus, a much higher number of samples than those currently obtained are needed to complete the catalog of driver mutations in human osteosarcoma. In parallel, genetic studies in other species have revealed candidate driver genes and their roles in the genesis of osteosarcoma. This review also summarizes newly identified drivers in genetically engineered mouse models (GEMMs) and discusses our understanding of the impact of nature and number of drivers on tumor latency, subtypes, and metastatic potentials of osteosarcoma. It is becoming apparent that a synergistic team composed of three drivers (one 'first driver' and two 'synergistic drivers') may be required to generate an animal model that recapitulates aggressive osteosarcoma with a short latency. Finally, new cancer therapies are urgently needed to improve survival rate and quality of life for osteosarcoma patients. Several vulnerabilities in osteosarcoma are illustrated in this review to exemplify the opportunities for next generation molecularly targeted therapies. However, much work remains in order to complete our understanding of the somatic mutation basis of osteosarcoma, to develop reliable animal models of human disease, and to apply this information to guide new therapeutic approaches for reducing morbidity and mortality of this rare disease.

Custom facial reconstruction for osteosarcoma of the jaw

Osteosarcoma accounts for most primary bone cancers in children and young adults. High-grade lesions are typically managed with a combination of chemotherapy and wide-margin surgical excision. Although this malignancy typically affects the metaphyseal region of long bones, it also can be seen in the axial skeleton. Of axial locations, tumors in the head and neck can be particularly troubling to treat. Segmental bone loss after resection of malignant mandibular tumors continues to present important challenges to the reconstructive surgeon. Recent advancements in 3-dimensional modeling have facilitated custom templates for patient-specific reconstructions. This report describes the case of a young woman with osteosarcoma of the mandible undergoing customized template composite facial reconstruction using a vascularized osteoseptocutaneous fibula flap.

MACC1 is involved in the regulation of proliferation, colony formation, invasion ability, cell cycle distribution, apoptosis and tumorigenicity by altering Akt signaling pathway in human osteosarcoma

There is mounting evidence that metastasis-associated in colon cancer-1 (MACC1) plays pivotal roles in development and progression of many tumors, particularly in osteosarcoma (OS). However, its precise roles and molecular mechanisms remain to be delineated in OS. In the current study, we found that the levels of MACC1 mRNA and protein in four OS cell lines (MG-63, HOS, SaOS-2 and U2OS) were significantly higher than that in hFOB1.19 osteoblast (P < 0.05). The vector pcDNA-MACC1 contributed to the increase of MACC1 level in MG-63 cells, whereas MACC1 siRNA evoked the decrease of MACC1 level in U2OS cells. In addition, MACC1 downregualtion caused the inhibition of cell proliferation in vitro, colony formation, invasion and tumor growth in vivo, arrested cell cycle in G0/G1 phase and induced cell apoptosis in U2OS cells, and reversed effects were observed in MG-63 cells by MACC1 upregulation. Most notably, MACC1 depletion markedly inactivated Akt signaling pathway in U2OS cells, conversely, MACC1 upregulation evidently activated Akt signaling pathway in MG-63 cells. Collectively, our data presented herein suggest that biological implications triggered by MACC1 may be tightly associated with the status of Akt signaling pathway in OS.

Capsaicin induces apoptosis in MG63 human osteosarcoma cells via the caspase cascade and the antioxidant enzyme system

Osteosarcoma is the most common malignant bone tumor in children and adolescents. This aggressive cancer mostly occurs in the long bones. Therefore, novel therapeutic approaches, such as biological therapies and gene therapy, are required to efficiently treat osteosarcoma. Capsaicin (trans-8-methyl-N-vanillyl-6-nonenamide) has been demonstrated to inhibit the growth of several types of cancer cells and a number of studies have shown that osteosarcoma may be vulnerable to biological therapies. However, little is known regarding the therapeutic effects of capsaicin on osteosarcoma. This study investigated the effects of capsaicin on MG63 human osteosarcoma cells, in addition to elucidating the regulatory signaling pathways underlying the effects of capsaicin, the caspase cascade and the antioxidant enzyme system. The MG63 cell line was treated with various concentrations of capsaicin. Cells were analyzed using MTT and flow cytometry, and the presence of DNA fragmentation was evaluated using TUNEL assay. Results showed capsaicin induced apoptosis in MG63 cells. Thus, capsaicin exhibited an anticancer effect in osteosarcoma cells.

Role of integrin-linked kinase in osteosarcoma progression

Although integrin-linked kinase (ILK) has been suggested to play a role in the tumorigenesis of a number of human epithelial carcinomas, little is known of its role in musculoskeletal sarcoma. The authors studied ILK expression by immunohistochemistry using osteosarcoma prechemotherapy specimens from 56 patients, and investigated the prognostic implications of the findings obtained. It was found that ILK overexpression was significantly correlated with the presence of distant metastasis (p = 0.008) and that it was an independent prognostic factor for both poor overall survival and poor event-free survival (p = 0.015 and 0.010, respectively). During a transfection experiment conducted by transfecting osteosarcoma cells with ILK siRNA, VEGF concentrations were measured using an ELISA kit, and then compared with those of untransfected controls to evaluate its angiogenic effects. In addition, apoptotic percentages were measured by Annexin-V flow cytometry, and invasive properties were evaluated by measuring the numbers of non-migrating cells in a Boyden chamber. It was found that ILK downregulation significantly decreased angiogenesis, increased apoptosis, and decreased invasiveness of osteosarcoma cells. These results show that ILK is a promising prognostic factor in osteosarcoma and a novel potential therapeutic target for the treatment of osteosarcoma.

High expression of MACC1 predicts poor prognosis in patients with osteosarcoma

Increasing evidence has demonstrated that high metastasis-associated in colon cancer-1 (MACC1) level is tightly associated with the development, progression, and poor prognosis of a variety of tumors. However, the relationship between MACC1 and the occurrence, development, and progression of osteosarcoma (OS) remains to be clarified. To facilitate and deepen the understanding of the associations of MACC1 with the development and progression of OS, in the current study, we detected the expressions of MACC1 mRNA and protein, and investigated the relationship between MACC1 expression and prognosis of the patients with OS. Our findings demonstrated that expressions of MACC1 mRNA and protein in OS tissues were significantly higher than those in paired normal bone tissues (P < 0.05). Additionally, the level of MACC1 mRNA in the patients with higher clinical stage and distant metastasis was markedly higher than those with lower clinical stage and without metastasis (P < 0.05). Furthermore, high MACC1 level was closely correlated with clinical stage and distant metastasis (P < 0.05), but not related to the patients' age, gender, tumor size, and anatomical location (P > 0.05). Stepwise investigation revealed that survival time of the patients with high MACC1 level was obviously lower than that with low MACC1 level (P < 0.05). Collectively, our data suggest that MACC1 may play important roles in the development and progression of OS, and thus may be considered as a novel molecular target for therapy of the patients with OS.

Imaging guidelines for children with Ewing sarcoma and osteosarcoma: a report from the Children's Oncology Group Bone Tumor Committee

The Children's Oncology Group (COG) is a multi-institutional cooperative group dedicated to childhood cancer research that has helped to increase the survival of children with cancer through clinical trials. These clinical trials include a standardized regimen of imaging examinations performed prior to, during, and following therapy. This article presents imaging guidelines developed by a multidisciplinary group from the COG Bone Tumor Committee. These guidelines provide both required and recommended studies. Recommended examinations may become required in the future. These guidelines should be considered a work in progress that will evolve with advances in imaging and childhood cancer research.

Prognostic value of bax, cytochrome C, and caspase-8 protein expression in primary osteosarcoma

The prognostic significance of bax, cytochrome c, and caspase-8 in patients with primary osteosarcoma is unknown. We examined the immunohistochemical expression of these genes in 35 surgically treated patients with primary osteosarcoma. Clinicopathological and survival data were correlated with the staining result. Eighteen tissue specimens from non-malignant osseous lesions were used as controls. Bax, cytochrome c, and caspase-8 positive staining was observed in 29 (82.9%), 16 (45.7%), and 0 (0%) patients, respectively, but did not stain any of the 18 benign osseous lesions used as controls. None of the genes studied predicted overall or disease-free survival. Patients, however, bearing bax(+)/cytochrome c(+) or bax(+)/cytochrome c(+ +) tumors had a decreased 4-year disease-free survival rate compared to the rest of the group (p = 0.0489 and p = 0.0208, respectively), identifying two groups of patients where more intensive adjuvant treatment could possibly be applied to prevent high postoperative recurrence rates.

Establishment and characterization of a KIT-positive and stem cell factor-producing cell line, KTHOS, derived from human osteosarcoma

Osteosarcoma is a malignant bone tumor that commonly affects adolescents and young adults. In the present study a human osteosarcoma cell line, KTHOS, was established from a primary osteosarcoma lesion in the distal femur of a 16-year-old girl. After 106 passages, the KTHOS cell line retained the biological characteristics of osteosarcoma. The KTHOS cells had spindle to pleomorphic cytoplasm with round to ovoid nuclei containing multiple prominent nucleoli, as expected based on the mesodermic origin of osteoblasts. The KTHOS cells were immunoreactive for osteocalcin, osteonectin, stem cell factor (SCF), and KIT (CD117). Reverse transcriptase-polymerase chain reaction indicated that the KTHOS cell line expressed mRNA for SCF and KIT. The KTHOS cells produced relatively high amounts of soluble SCF as determined by enzyme-linked immunosorbent assay. The results suggest that cell proliferation of the KTHOS cell line might be involved in autocrine and/or paracrine loops of the SCF/KIT signaling system. The KTHOS cell line is a novel human osteosarcoma cell line that releases SCF and expresses KIT. This cell line can be used for studies to explore the mechanisms for oncogenesis of human osteosarcomas.

Impact of National Health Insurance on the Survival Rate of Patients with Osteosarcoma In Taiwan: Review of 74 Patients

The 2-year survival rate for high-grade osteosarcoma was 46.9% before the introduction of National Health Insurance (NHI) in Taiwan on March 1, 1995, but increased to 73.8% after the implementation of NHI. The 5-year survival rate also increased, from 37.5% to 63.6%. Between May 1990 and May 2001, 74 patients with high-grade osteosarcoma were treated at our hospital. Median age was 17 years (range, 7-63 years). Inadequate surgical margins, poor histologic response to chemotherapy, advanced stage of disease, and incomplete treatment were strongly associated with poor prognosis. Before NHI, 10 patients had incomplete treatment, mainly because of unaffordable medical fees. After NHI, only three patients had incomplete treatment, due to personal reasons. Patient survival improved dramatically with advances in multiagent chemotherapy, but it was the NHI that enabled patients to complete expensive treatment courses, including preoperative neoadjuvant chemotherapy, limb-salvage surgery, and postoperative adjuvant chemotherapy. The NHI also improved the accessibility of medical care, with more patients presenting in the early stages of disease and, as a result, it not only improved survival rate but also increased the number of patients undergoing limb-salvage surgery. We concluded that the NHI significantly improved the survival rate for patients with osteosarcoma in Taiwan.

Foot malignancies: a multidisciplinary approach

Malignant osseous and soft tissue tumors of the foot are rare and should be considered in patients who have foot-related symptoms. Most sarcomas affect patients who are older than 55 years; however, many young patients who are otherwise healthy, may present with malignant foot and ankle lesions. In addition to benign and malignant neoplasms, pseudotumorous conditions mimic neoplastic lesions and should be differentiated before any treatment is undertaken. Invasiveness is a characteristic of sarcomas. The foot is a terminal anatomic structure, with closed and tight compartments and well-vascularized tissues, that predispose it to hematogenous and lymphatic metastases. Patients who have a malignant foot tumor should be referred to an orthopedic oncologist for further evaluation and treatment. The goals of treatment include local tumor control, restoration of function and stability during standing and walking, long-term survival, and improved quality of life. In most cases, wide surgical margins require a ray, Syme, midtarsal, or below-the-knee amputation. Recent advances in chemotherapy and radiotherapy have allowed limb salvage procedures with wide tumor resections. Because overall survival is greatly improved in these patients, the reconstruction of skeletal defects needs to be more functional and durable. After tumor resection, reconstruction of the skeletal and soft tissue defects is possible by using bone allografts or vascularized autografts, arthrodesis, and free vascularized musculocutaneous flaps.

Sustained loss of a neoplastic phenotype by brief inactivation of MYC

Pharmacological inactivation of oncogenes is being investigated as a possible therapeutic strategy for cancer. One potential drawback is that cessation of such therapy may allow reactivation of the oncogene and tumor regrowth. We used a conditional transgenic mouse model for MYC-induced tumorigenesis to demonstrate that brief inactivation of MYC results in the sustained regression of tumors and the differentiation of osteogenic sarcoma cells into mature osteocytes. Subsequent reactivation of MYC did not restore the cells' malignant properties but instead induced apoptosis. Thus, brief MYC inactivation appears to cause epigenetic changes in tumor cells that render them insensitive to MYC-induced tumorigenesis. These results raise the possibility that transient inactivation of MYC may be an effective therapy for certain cancers.

Imaging in skeletal paediatric oncology

The prognosis for the child presenting with a bone sarcoma has improved dramatically with the introduction of adjuvent chemotherapy. As a result the majority of patients can now expect to undergo limb salvage surgery. The role of imaging in the management of the child presenting with a suspected sarcoma is presented. This commences with tumour detection, through diagnosis and surgical staging, re-staging with assessment of response to chemotherapy and follow-up surveillance for the development of local recurrence and/or metastases. The importance of the multidisciplinary approach to the management of bone sarcomas is emphasised.