Salvage of a Fractured Proximal Ulnar Osteoarticular Allograft Using a Medial Femoral Condyle Free Flap: A Case Report.

CASE: We present the case of a 47-year-old paraplegic woman who underwent resection of an intermediate-grade chondrosarcoma in the proximal ulna, which was initially reconstructed with an osteoarticular allograft. However, after more than 25 years without complications, she sustained an intra-articular fracture of the allograft, which was then successfully treated using a vascularized medial femoral condyle (MFC) flap and anterolateral thigh flap. The patient has subsequently recovered her baseline elbow function, has no pain, and can use her wheelchair without restrictions. CONCLUSION: Free MFC flaps are viable options to salvage osteoarticular allografts that are affected by intra-articular fractures.

Active surveillance of atypical cartilaginous tumours of bone: short term quality of life measurements.

BACKGROUND: In the recent years active surveillance has been introduced for atypical cartilaginous tumours (ACT). This is the first study on the impact of this new treatment approach on patients' quality-of-life. We evaluated general health-related quality of life (HRQL) in patients diagnosed with enchondroma or ACT. METHODS: In this prospective study, patients recently diagnosed with enchondroma and ACT of the long bones were asked to participate. Health-related quality of life (HRQL) was assessed at diagnosis and at six month follow-up, using the 36-item Short Form Health Survey (SF-36) and Numeric Pain Rating Scale (NRS). HRQL of the active surveillance group was compared to the Dutch population and a Dutch sample with locoregional cancer. RESULTS: In total, 45 patients were included in the study, of which four patients underwent curettage and cryosurgery, 41 patients were under active surveillance. The HRQL of the active surveillance group seemed lower compared to the Dutch population, but similar to patients suffering locoregional cancers. No comparison between the surgery and the active surveillance group could be made. In the active surveillance group no statistical difference was found between baseline and six months follow-up regarding HRQL and pain during rest and activities. CONCLUSION: Patients diagnosed with non-malignant chondroid tumours have lower HRQL compared to the healthy population. Active surveillance had no adverse effect on patients well-being, after six months active surveillance the HRQL remained unchanged. Interestingly, in our study no impact on mental health was seen, implicating that diagnosed but untreated chondroid tumours do not seem to influence patients anxiety.

Midterm MRI Follow-Up of Untreated Enchondroma and Atypical Cartilaginous Tumors in the Long Bones.

Management of atypical cartilaginous tumors (ACTs) in the long bones is shifting towards active surveillance to avoid unnecessary surgeries. The frequency and duration of active surveillance for these tumors is unclear as there is little knowledge of its biological behavior. In this retrospective study, we examined the natural course of enchondroma and ACTs through active surveillance. A total of 128 central cartilaginous tumors, located in the long bones, with a minimum interval of 24 months between baseline and last MRI were included. MRI characteristics (e.g., size, scalloping, fat entrapment) were scored and tumors were classified according to the changes between MRIs. Mean follow-up of this study was 50 months, range = 25-138 months. The majority of the cartilaginous tumors (87%) remained stable (n = 65) or showed regression (n = 46) on MRI. A total of 87% of the cases that developed tumor regression presented with entrapped fat at diagnosis. Only 13% (n= 17) showed some progression on MRI, although none of the tumors developed characteristics of high-grade chondrosarcoma. Based on our results, active surveillance is considered safe for enchondroma and ACTs of the long bones. We propose active surveillance for all asymptomatic enchondroma or ACTs in the long bones irrespective of tumor size, and follow-up schemes should be tailored on natural course.

Curettage and cryosurgery for enchondroma and atypical cartilaginous tumors of the long bones: Oncological results of a large series.

BACKGROUND AND OBJECTIVES: Intralesional surgical treatment is the preferred therapy for atypical cartilaginous tumors (ACTs) of the long bones in many institutions. However, the literature is still controversial regarding intralesional treatment versus wide resection. Due to the relative rarity of these tumors, studies reporting on the results of intralesional treatment are often small sample studies. METHODS: We retrospectively analyzed the oncological results of 55 enchondromas, 119 ACTs, and 5 chondrosarcomas grade 2 (CS2) treated with curettage and cryosurgery between the years 2004 and 2017 at our institution. The median follow-up period was 53 months (range, 24-169 months). RESULTS: In total, seven cases (three ACT, four CS2) recurred. Residual tumor was detected in 20 cases. Three cases underwent secondary curettage and cryosurgery due to local recurrence. Four cases underwent wide resection and reconstruction due to local recurrence with aggressive imaging characteristics. In total, 20 postoperative complications were seen. CONCLUSION: Curettage and cryosurgery for enchondroma and ACT show very good oncological results with a low recurrence rate and acceptable complication rate. Curettage and cryosurgery is reliable as a surgical treatment for enchondroma and ACT. Further research should define the criteria for determining which specific cartilaginous tumors necessitate surgical treatment.

Health-related quality of life after interval cytoreductive surgery with or without hyperthermic intraperitoneal chemotherapy (HIPEC) in patients with stage III ovarian cancer.

INTRODUCTION: The addition of hyperthermic intraperitoneal chemotherapy (HIPEC) to interval cytoreductive surgery (CRS) improves recurrence-free (RFS) and overall survival (OS) in patients with FIGO stage III ovarian cancer. We evaluated the effect of HIPEC on patient's health-related quality of life (HRQoL) in the OVHIPEC trial. MATERIALS AND METHODS: OVHIPEC was a multicentre, open-label, randomized phase III trial for patients with stage III ovarian cancer. Patients were randomly assigned (1:1) to receive interval CRS with or without HIPEC with cisplatin. HRQoL was assessed using the EORTC QLQ-C30, and the ovarian (QLQ-OV28) and colorectal cancer (QLQ-CR38) modules. HRQoL questionnaires were administered at baseline, after surgery, after end of treatment, and every three months thereafter. HRQoL was a secondary endpoint, with the prespecified focus on the QLQ-C30 summary score and symptom scores on fatigue, neuropathy and gastro-intestinal symptoms. HRQoL was analysed using linear and non-linear mixed effect models. RESULTS: In total, 245 patients were randomized. One-hundred-ninety-seven patients (80%) completed at least one questionnaire. No significant difference over time in the QLQ-C30 summary scores was observed between the study arms (p-values for linear and non-linear growth: p > 0.133). The pattern over time for fatigue, neuropathy and gastro-intestinal symptoms did not significantly differ between treatment arms. CONCLUSION: The addition of HIPEC to interval CRS does not negatively impact HRQoL in patients with stage III ovarian cancer who are treated with interval CRS due to the extent of disease. These HRQoL results, together with the improvement in RFS and OS, support the viability of HIPEC as an important treatment option in this patient population. CLINICALTRIALS. GOV NUMBER: NCT00426257. EUDRACT NUMBER: 2006-003466-34.

Analysis of Drug Metabolizing Gene Panel in Osteosarcoma Patients Identifies Association Between Variants in SULT1E1, CYP2B6 and CYP4F8 and Methotrexate Levels and Toxicities.

High-dose methotrexate is a cornerstone agent in the chemotherapeutic treatment of patients with osteosarcoma. However, patients often develop methotrexate-induced toxicities. We aim to identify determinants of methotrexate-induced toxicities in osteosarcoma patients by investigating the relation between drug plasma levels, methotrexate-induced toxicities, and germline variants in genes related to drug absorption, distribution, metabolism, and elimination. A cohort of 114 osteosarcoma patients was genotyped for 1,931 variants in 231 genes using the Drug Metabolism Enzymes and Transporters Plus array. Methotrexate plasma levels and laboratory measurements during and after high-dose methotrexate treatment concerning renal function, liver damage, and myelopoiesis to reflect toxicity outcomes were obtained. One hundred and thirteen patients and a subset of 545 variants in 176 genes passed quality control checks. Methotrexate plasma levels showed associations with creatinine, alanine aminotransferase, and hemoglobin. Genetic variant rs3736599 in the 5'-untranslated region of SULT1E1 was associated with lower 48 hour methotrexate plasma levels [coef -0.313 (95% CI -0.459 - -0.167); p = 2.60 × 10-5]. Association with methotrexate-induced decreased thrombocyte counts was found for two intronic variants in CYP2B6 {rs4803418 [coef -0.187 (95% CI -0.275 - -0.099); p = 3.04 × 10-5] and rs4803419 [coef -0.186 (95% CI -0.278 - -0.093); p = 8.80 × 10-5]}. An association with increased thrombocyte counts was identified for the intronic variant rs4808326 in CYP4F8 [coef 0.193 (95% CI 0.099 - 0.287); p = 6.02 × 10-5]. Moreover, a secondary analysis with a binary approach using CTCAE toxicity criteria resulted in a nominal significant associations (p < 0.05) for two out of three variants (rs4803418 and rs4808326). This is the first study to identify genetic variants in SULT1E1, CYP2B6, and CYP4F8 to be associated with methotrexate pharmacokinetics and toxicities. Validation of these variants in an independent cohort and further functional investigation of variants in the identified genes is needed to determine if and how they affect methotrexate plasma levels and the development of methotrexate-induced toxicities.

Can MRI differentiate between atypical cartilaginous tumors and high-grade chondrosarcoma? A systematic review.

Background and purpose - Adequate staging of chondroid tumors at diagnosis is important as it determines both treatment and outcome. This systematic review provides an overview of MRI criteria used to differentiate between atypical cartilaginous tumors (ACT) and high-grade chondrosarcoma (HGCS).Patients and methods - For this systematic review PubMed and Embase were searched, from inception of the databases to July 12, 2018. All original articles describing MRI characteristics of pathologically proven primary central chondrosarcoma and ACT were included. A quality appraisal of the included papers was performed. Data on MRI characteristics and histological grade were extracted by 2 reviewers. Meta-analysis was performed if possible. The study is registered with PROSPERO, CRD42018067959.Results - Our search identified 2,132 unique records, of which 14 studies were included. 239 ACT and 140 HGCS were identified. The quality assessment showed great variability in consensus criteria used for both pathologic and radiologic diagnosis. Due to substantial heterogeneity we refrained from pooling the results in a meta-analysis and reported non-statistical syntheses. Loss of entrapped fatty marrow, cortical breakthrough, and extraosseous soft tissue expansion appeared to be present more often in HGCS compared with ACT.Interpretation - This systematic review provides an overview of MRI characteristics used to differentiate between ACT and HGCS. Future studies are needed to develop and assess more reliable imaging methods and/or features to differentiate ACT from HGCS.

The effect of surgery in tenosynovial giant cell tumours as measured by patient-reported outcomes on quality of life and joint function.

AIMS: The aim of this study was to evaluate health-related quality of life (HRQoL) and joint function in tenosynovial giant cell tumour (TGCT) patients before and after surgical treatment. PATIENTS AND METHODS: This prospective cohort study run in two Dutch referral centres assessed patient-reported outcome measures (PROMs; 36-Item Short-Form Health Survey (SF-36), visual analogue scale (VAS) for pain, and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC)) in 359 consecutive patients with localized- and diffuse-type TGCT of large joints. Patients with recurrent disease (n = 121) and a wait-and-see policy (n = 32) were excluded. Collected data were analyzed at specified time intervals preoperatively (baseline) and/or postoperatively up to five years. RESULTS: A total of 206 TGCT patients, 108 localized- and 98 diffuse-type, were analyzed. Median age at diagnosis of localized- and diffuse-type was 41 years (interquartile range (IQR) 29 to 49) and 37 years (IQR 27 to 47), respectively. SF-36 analyses showed statistically significant and clinically relevant deteriorated preoperative and immediate postoperative scores compared with general Dutch population means, depending on subscale and TGCT subtype. After three to six months of follow-up, these scores improved to general population means and continued to be fairly stable over the following years. VAS scores, for both subtypes, showed no statistically significant or clinically relevant differences pre- or postoperatively. In diffuse-type patients, the improvement in median WOMAC score was statistically significant and clinically relevant preoperatively versus six to 24 months postoperatively, and remained up to five years' follow-up. CONCLUSION: Patients with TGCT report a better HRQoL and joint function after surgery. Pain scores, which vary hugely between patients and in patients over time, did not improve. A disease-specific PROM would help to decipher the impact of TGCT on patients' daily life and functioning in more detail. Cite this article: Bone Joint J 2019;101-B:272-280.

Severity classification of Tenosynovial Giant Cell Tumours on MR imaging.

AIM: Current development of novel systemic agents requires identification and monitoring of extensive Tenosynovial Giant Cell Tumours (TGCT). This study defines TGCT extension on MR imaging to classify severity. METHODS: In part one, six MR parameters were defined by field-experts to assess disease extension on MR images: type of TGCT, articular involvement, cartilage-covered bone invasion, and involvement of muscular/tendinous tissue, ligaments or neurovascular structures. Inter- and intra-rater agreement were calculated using 118 TGCT MR scans. In part two, the previously defined MR parameters were evaluated in 174 consecutive, not previously used, MR-scans. TGCT severity classification was established based on highest to lowest Hazard Ratios (HR) on first recurrence. RESULTS: In part one, all MR parameters showed good inter- and intra-rater agreement (Kappa≥0.66). In part two, cartilage-covered bone invasion and neurovascular involvement were rarely appreciated (<13%) and therefore excluded for additional analyses. Univariate analyses for recurrent disease yielded positive associations for type of TGCT HR12.84(95%CI4.60-35.81), articular involvement HR6.00(95%CI2.14-16.80), muscular/tendinous tissue involvement HR3.50(95%CI1.75-7.01) and ligament-involvement HR4.59(95%CI2.23-9.46). With these, a TGCT severity classification was constructed with four distinct severity-stages. Recurrence free survival at 4 years (log rank p < 0.0001) was 94% in mild localized (n56, 1 recurrence), 88% in severe localized (n31, 3 recurrences), 59% in moderate diffuse (n32, 12 recurrences) and 36% in severe diffuse (n55, 33 recurrences). CONCLUSION: The proposed TGCT severity classification informs physicians and patients on disease extent and risk for recurrence after surgical treatment. Definition of the most severe subgroup attributes to a universal identification of eligible patients for systemic therapy or trials for novel agents.

Treatments of tenosynovial giant cell tumours of the temperomandibular joint: a report of three cases and a review of literature.

Tenosynovial giant cell tumours (TGCTs) are benign lesions affecting synovial joints. The classified subtypes are localized and diffuse. They seldom occur in the temporomandibular joint (TMJ). The aim of this study is to report on three new cases and to review the literature. One patient had surgical debulking with adjuvant external beam radiation therapy (EBRT). After 1year of follow-up, no evidence of disease was presented. The second patient was misdiagnosed and treated with denosumab. Debulking with adjuvant EBRT followed. Ten months postoperatively, no disease progression was seen. The third patient received systemic nilotinib and remained stable for over 5years. The literature review included 106 cases of which 95 had diffuse subtype. Most patients, had surgical excision. Thirteen (14%) patients received adjuvant EBRT. Eleven (14%) recurrences were identified. After 1-, 5- and 10 years of follow-up, an overall progression-free survival (PFS) of 99% (95% confidence interval (CI) 0.96-1), 80% (95% CI 0.68-0.94), 67% (95% CI 0.51-0.90) was calculated, respectively. Treatments for diffuse-TGCT-TMJ should be individualized depending on age, severity of symptoms, extent of disease and progression, expected mutilation of surgical interference, and current systemic treatment options. In stable disease a 'wait and see' policy, is a viable option. Additional treatments should be reserved for symptomatic, irresectable tumours or residual disease after surgical treatment with persistent complaints.

Tenosynovial Giant Cell Tumors in Children: A Similar Entity Compared With Adults.

BACKGROUND: Tenosynovial giant cell tumor (TGCT) is a rare, benign, monoarticular entity. Many case-series in adults are described, whereas TGCT is only incidentally reported in children. Therefore, its incidence rate and natural history in children are unknown. QUESTIONS/PURPOSES: (1) How many cases have been reported of this condition, and what were their characteristics? (2) What is the standardized pediatric incidence rate for TGCT? (3) Is there a clinical difference in TGCT between children and adults? (4) What is the risk of recurrence after open resection in children compared with adults? METHODS: Data were derived from three sources: (1) a systematic review on TGCT in children, seeking sources published between 1990 and 2016, included 17 heterogeneous, small case-series; (2) the nationwide TGCT incidence study: the Dutch pediatric incidence rate was extracted from this nationwide study by including patients younger than 18 years of age. This registry-based study, in which eligible patients with TGCT were clinically verified, calculated Dutch incidence rates for localized and diffuse-type TGCT in a 5-year timeframe. Standardized pediatric incidence rates were obtained by using the direct method; (3) from our nationwide bone and soft tissue tumor data registry, a clinical data set was derived. Fifty-seven children with histologically proven TGCT of large joints, diagnosed and treated between 1995 and 2015, in all four tertiary sarcoma centers in The Netherlands, were included. These clinically collected data were compared with a retrospective database of 423 adults with TGCT. Chi-square test and independent t-test were used to compare children and adults for TGCT type, sex, localization, symptoms before diagnosis, first treatment, recurrent disease, followup status, duration of symptoms, and time to followup. The Kaplan-Meier method was used to evaluate recurrence-free survival at 2.5 years. RESULTS: TGCT is seldom reported because only 76 pediatric patients (39 female), 29 localized, 38 diffuse, and nine unknown type, were identified from our systematic review. The standardized pediatric TGCT incidence rate of large joints was 2.42 and 1.09 per million person-years in localized and diffuse types, respectively. From our clinical data set, symptoms both in children and adults were swelling, pain, and limited ROM with a median time before diagnosis of 12 months (range, 1-72 months). With the numbers available, we did not observe differences in presentation between children and adults in terms of sex, symptoms before diagnosis, first treatment, recurrent disease, followup status, or median time to followup. The 2.5-year recurrence-free TGCT survival rate after open resection was not different with the numbers available between children and adults: 85% (95% confidence interval [CI], 67%-100%) versus 89% (95% CI, 83%-96%) in localized, respectively (p = 0.527) and 53% (95% CI, 35%-79%) versus 56% (95% CI, 49%-64%) in diffuse type, respectively (p = 0.691). CONCLUSIONS: Although the incidence of pediatric TGCT is low, it should be considered in the differential diagnosis in children with chronic monoarticular joint effusions. Recurrent disease after surgical treatment of this orphan disease seems comparable between children and adults. With targeted therapies being developed, future research should define the most effective treatment strategies for this heterogeneous disease. LEVEL OF EVIDENCE: Level III, therapeutic study.

Higher incidence rates than previously known in tenosynovial giant cell tumors.

Background and purpose - Tenosynovial giant cell tumors (TGCT) are rare, benign tumors, arising in synovial lining of joints, tendon sheaths, or bursae. 2 types are distinguished: localized, either digits or extremity, and diffuse lesions. Current TGCT incidence is based on 1 single US-county study in 1980, with an incidence of 9 and 2 per million person-years in localized (including digits) and diffuse TGCT, respectively. We aim to determine nationwide and worldwide incidence rates (IR) in TGCT affecting digits, localized-extremity TGCT and diffuse-type TGCT. Material and methods - Over a 5-year period, the Dutch Pathology Registry (PALGA) identified 4,503 pathology reports on TGCT. Reports affecting digits were solely used for IR calculations. Reports affecting extremities were clinically evaluated. Dutch IRs were converted to world population IRs. Results - 2,815 (68%) digits, 933 (23%) localized-extremity and 390 (9%) diffuse-type TGCT were identified. Dutch IR in digits, localized-extremity, and diffuse-type TGCT was 34, 11 and 5 per million person-years, respectively. All 3 groups showed a female predilection and highest number of new cases in age category 40-59 years. The knee joint was most often affected: localized-extremity (46%) and diffuse-type (64%) TGCT, mostly treated with open resection: localized (65%) and diffuse (49%). Reoperation rate due to local recurrence for localized-extremity was 9%, and diffuse TGCT 23%. Interpretation - This first nationwide study and detailed analyses of IRs in TGCT estimated a worldwide IR in digits, localized-extremity and diffuse TGCT of 29, 10, and 4 per million person-years, respectively. Recurrence rate in diffuse type is 2.6 times higher, compared with localized extremity. TGCT is still considered a rare disease; however, it is more common than previously understood.

Arthroplasty for tenosynovial giant cell tumors.

Background and purpose - Tenosynovial giant cell tumors (t-GCTs) can behave aggressively locally and affect joint function and quality of life. The role of arthroplasty in the treatment of t-GCT is uncertain. We report the results of arthroplasty in t-GCT patients. Patients and methods - t-GCT patients (12 knee, 5 hip) received an arthroplasty between 1985 and 2015. Indication for arthroplasty, recurrences, complications, quality of life, and functional scores were evaluated after a mean follow-up time of 5.5 (0.2-15) years. Results - 2 patients had recurrent disease. 2 other patients had implant loosening. Functional scores showed poor results in almost half of the knee patients. 4 of the hip patients scored excellent and 1 scored fair. Quality of life was reduced in 1 or more subscales for 2 hip patients and for 5 knee patients. Interpretation - In t-GCT patients with extensive disease or osteoarthritis, joint arthroplasty is an additional treatment option. However, recurrences, implant loosening, and other complications do occur, even after several years.

Cryosurgery as Additional Treatment in Tenosynovial Giant Cell Tumors.

Introduction. Tenosynovial giant cell tumors (TGCT) emerge from the synovium and can behave aggressively. Surgical resection is the standard treatment. However, up to half of the patients with diffuse type show recurrences. Several additional treatments have been applied to reduce recurrences; none of these treatments was proven to be superior to surgical resection solely. This article describes the results of additional cryosurgery to surgical resection. Materials and Methods. We retrospectively evaluated 141 TGCT patients, between 1999 and 2007. Twelve patients had additional cryosurgery. The knee (n = 8), hip (n = 2), ankle (n = 1), and elbow (n = 1) were affected. Primary outcome variables were treatment indications, recurrences, and complications. Results. Indications for additional cryosurgery were extended disease, bone involvement, and locations that are difficult to surgically get disease-free such as cruciate ligaments. Five patients had recurrent disease, all of which had prior treatments. None of the primary treated patients had recurrent disease. One patient had a deep infection. Discussion. Cryosurgery may serve as an additional treatment for diffuse TCGT in selected cases. However, because of the small number of patients and the heterogeneous group we could not prove an advantage of additional cryosurgery over surgical resection only. Cryosurgery should be considered for further evaluation in a prospective study. If there is any effect it would be helpful, especially in patients with multiple TGCT recurrences.

Hemicortical resection and inlay allograft reconstruction for primary bone tumors: a retrospective evaluation in the Netherlands and review of the literature.

BACKGROUND: Selected primary tumors of the long bones can be adequately treated with hemicortical resection, allowing for optimal function without compromising the oncological outcome. Allografts can be used to reconstruct the defect. As there is a lack of studies of larger populations with sufficient follow-up, little is known about the outcomes of these procedures. METHODS: In this nationwide retrospective study, all patients treated with hemicortical resection and allograft reconstruction for a primary bone tumor from 1989 to 2012 were evaluated for (1) mechanical complications and infection, (2) oncological outcome, and (3) failure or allograft survival. The minimum duration of follow-up was twenty-four months. RESULTS: The study included 111 patients with a median age of twenty-eight years (range, seven to seventy-three years). The predominant diagnoses were adamantinoma (n = 37; 33%) and parosteal osteosarcoma (n = 18; 16%). At the time of review, 104 patients (94%) were alive (median duration of follow-up, 6.7 years). Seven patients (6%) died, after a median of twenty-six months. Thirty-seven patients (33%) had non-oncological complications, with host bone fracture being the most common (n = 20, 18%); all healed uneventfully. Other complications included nonunion (n = 8; 7%), infection (n = 8; 7%), and allograft fracture (n = 3; 3%). Of ninety-seven patients with a malignant tumor, fifteen (15%) had residual or recurrent tumor and six (6%) had metastasis. The risk of complications and fractures increased with the extent of cortical resection. CONCLUSIONS: Survival of hemicortical allografts is excellent. Host bone fracture is the predominant complication; however, none of these fractures necessitated allograft removal in our series. The extent of resection is the most important risk factor for complications. Hemicortical resection is not recommended for high-grade lesions; however, it may be superior to segmental resection for treatment of carefully selected tumors, provided that it is possible to obtain adequate margins. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

A First Step toward Personalized Medicine in Osteosarcoma: Pharmacogenetics as Predictive Marker of Outcome after Chemotherapy-Based Treatment.

PURPOSE: Overall survival in patients with osteosarcoma is only 60%. Poor response to chemotherapy is the dominant risk factor for poor survival. Pharmacogenetic research can offer possibilities to optimize treatment and improve outcome. We applied a pathway-based approach to evaluate the cumulative effect of genes involved in the metabolism of cisplatin and doxorubicin in relationship to clinical outcome. EXPERIMENTAL DESIGN: We included 126 patients with osteosarcoma. To comprehensively assess common genetic variation in the 54 genes selected, linkage disequilibrium (LD; r(2) = 0.8)-based tag-single nucleotide polymorphisms (SNP) strategy was used. A final set of 384 SNPs was typed using Illumina Beadarray platform. SNPs significantly associated with 5-year progression-free survival (PFS) were replicated in another 64 patients with osteosarcoma. RESULTS: We identified five variants in FasL, MSH2, ABCC5, CASP3, and CYP3A4 that were associated with 5-year PFS. Risk stratification based on the combined effects of the risk alleles showed a significant improvement of 5-year PFS. Patients that carried no or only one risk allele had a 5-year PFS of 100% compared with a 5-year PFS of 84.4% for carriers of two or three risk alleles, 66.7% PFS if a patient carried four to five alleles, and a 5-year PFS of 41.8% for patients with >5 risk alleles (P < 0.001). CONCLUSIONS: We identified several genes that showed association with PFS in patients with osteosarcoma. These pharmacogenetic risk factors might be useful to predict treatment outcome and to stratify patients immediately after diagnosis and offer the possibility to improve treatment and outcome.