Genetically engineered mouse models and human osteosarcoma

Osteosarcoma is the most common form of bone cancer. Pivotal insight into the genes involved in human osteosarcoma has been provided by the study of rare familial cancer predisposition syndromes. Three kindreds stand out as predisposing to the development of osteosarcoma: Li-Fraumeni syndrome, familial retinoblastoma and RecQ helicase disorders, which include Rothmund-Thomson Syndrome in particular. These disorders have highlighted the important roles of P53 and RB respectively, in the development of osteosarcoma. The association of OS with RECQL4 mutations is apparent but the relevance of this to OS is uncertain as mutations in RECQL4 are not found in sporadic OS. Application of the knowledge or mutations of P53 and RB in familial and sporadic OS has enabled the development of tractable, highly penetrant murine models of OS. These models share many of the cardinal features associated with human osteosarcoma including, importantly, a high incidence of spontaneous metastasis. The recent development of these models has been a significant advance for efforts to improve our understanding of the genetics of human OS and, more critically, to provide a high-throughput genetically modifiable platform for preclinical evaluation of new therapeutics.

Expression and significance of Kruppel-like factor 6 gene in osteosarcoma

PURPOSE

Osteosarcoma is primary malignant tumour of bone. Kruppel-like factor 6 (KLF6) is a tumor suppressor gene frequently inactivated in a number of human cancers and a ubiquitously expressed zinc-finger transcription factor. The present study aimed to first explore the relationship between the expression level of the KLF6 gene in osteosarcoma and the occurrence of bone tumours.

METHODS

KLF6 mRNA and protein expression levels in osteosarcoma and normal bone tissue were assayed by real-time quantitative PCR and immunohistochemistry. KLF6 mRNA and protein expression levels in osteosarcoma cells and normal osteoblasts were detected by semi-quantitative reverse transcription PCR and Western blotting, respectively.

RESULTS

Both the expression of KLF6 mRNA and protein in osteosarcoma cells and tissues were significantly lower than that in normal cells and tumour-adjacent tissues.

CONCLUSIONS

KLF6 is a putative tumor suppressor gene involved in osteosarcoma which can be used as a new therapeutic target and an important marker for early diagnosis and postoperative monitoring.

Multifocal primary bone sarcoma in the elderly: a rare case and review of the literature

To our knowledge there are no reports of a primary multifocal spindle cell sarcoma affecting both long bones of the lower limb in an elderly patient. An 83-year-old man presented with a progressively painful right ankle, without a history of trauma. Radiographs demonstrated a pathological fracture through a mixed lytic and sclerotic lesion in the distal tibia. Staging investigations, including bone scintigraphy and magnetic resonance imaging, revealed a second lytic lesion in the right distal femur. A provisional diagnosis of metastatic disease was favoured and intramedullary nailing was considered. However, computed tomography of the chest, abdomen and pelvis, and relevant blood tests revealed no evidence of a primary malignancy. Open biopsy of the tibial lesion showed high-grade pleomorphic spindle cells consistent with a primary bone sarcoma. The patient was treated successfully with a right trans-femoral amputation. In conclusion, we recommend early bone biopsy to allow accurate diagnosis and appropriate skeletal management in elderly patients.

Osteosarcoma: Differential Diagnostic Considerations

Accurate diagnosis of bone-forming tumors, including correct subclassification of osteogenic sarcoma is critical for determination of appropriate clinical management and prediction of patient outcome. The morphologic spectrum of osteogenic sarcoma is extensive, however, and its histologic mimics are numerous. This review focuses on the major differential diagnoses of the specific subtypes of osteosarcoma, presents summaries of various diagnoses, and provides tips to overcoming pitfalls in diagnosis.

Age as prognostic factor in patients with osteosarcoma

Age at diagnosis is a well known prognostic factor in many different malignancies; its significance for patients with osteosarcoma is however controversial. To gain more insight in the prognostic role of age, we performed a retrospective study at our institute. We included 102 patients with de-novo osteosarcoma and formed three age groups to evaluate age specific survival rates: ≤ 14 years, 15-19 years and 20-40 years. Differences in outcome between patients aged 15-19 years treated at either the pediatric department or the adult department of oncology were evaluated. The 5-year overall survival rate (OSR) of the whole population was 53.5%±1.5%. OSR of 70.6%±0.8% was seen in patients ≤ 14 years old, 52.5%±1.1% in patients 15-19 years old and 33.3%±0.9% in the patients aged 20-40 years (p=0.01). Significant differences were observed with regard to stage at presentation (higher in older age groups), size of the tumor (larger in younger age groups) and histological response (more good responders in younger age groups). No significant difference was seen between outcomes of patients aged 15-19 years treated at the pediatric or adult oncology department. In conclusion, younger patients have a significantly better outcome than older patients.

Using epidemiology and genomics to understand osteosarcoma etiology

Osteosarcoma is a primary bone malignancy that typically occurs during adolescence but also has a second incidence peak in the elderly. It occurs most commonly in the long bones, although there is variability in location between age groups. The etiology of osteosarcoma is not well understood; it occurs at increased rates in individuals with Paget disease of bone, after therapeutic radiation, and in certain cancer predisposition syndromes. It also occurs more commonly in taller individuals, but a strong environmental component to osteosarcoma risk has not been identified. Several studies suggest that osteosarcoma may be associated with single nucleotide polymorphisms in genes important in growth and tumor suppression but the studies are limited by sample size. Herein, we review the epidemiology of osteosarcoma as well as its known and suspected risk factors in an effort to gain insight into its etiology.

The threat of misdiagnosis of primary osteosarcoma over the age of 60: a series of seven cases and review of the literature

BACKGROUND

Osteosarcoma is the most common, non-haematopoietic, primary malignant bone tumour with an incidence of 0.3-0.5 per 100,000. There is some discrepancy in literature concerning the peaks of incidence of osteosarcoma. Some describe only one peak which arises in adolescence, whilst others report a bimodal age distribution with a second peak over the age of 60. In this retrospective study, we evaluated osteosarcoma patients over age 60 treated at our department and reviewed previous studies from the literature.

PATIENTS AND METHODS

Sixty-four patients (40 male, 24 female) with a mean age of 29 years (from 7 to 82) were treated for primary osteosarcomas. At the time of diagnosis, seven patients (two male and five female) were over 60 years of age with a mean follow-up of 46 months after definite diagnosis.

RESULTS

Three out of seven osteosarcomas were primarily radiologically or histologically misdiagnosed, but only one was mistreated with intramedullary nailing at a trauma centre. At last follow-up, two patients had died from the disease, three were alive with disease, and two had no evidence of osteosarcoma.

CONCLUSIONS

We did not find an increased incidence of primary osteosarcoma in the elderly; yet, older patients had a higher rate of misdiagnosis due to untypical radiological findings in combination with longer times from the onset of first symptoms to definite diagnosis. In cases of pathological fracture, it is essential to assess whether it is caused by mechanical stress or a primary or secondary tumour before leading into mistreatment, especially in older patients.

Bone versus soft-tissue sarcomas in the elderly

PURPOSE

To compare survival rates in the elderly with bone versus soft-tissue sarcomas.

METHODS

Records of 12 men and 8 women aged 70 to 91 (mean, 77) years with bone or soft-tissue sarcomas were retrospectively reviewed. The grade, size, location, and stage of the sarcomas, as well as their surgical margins, treatment modalities, local recurrence, metastasis, and prognosis were recorded. The mean follow-up period was 37 (range, 2-137) months. Their 5-year survival rates were estimated using the Kaplan-Meier method, and compared with 110 younger controls aged 9 to 69 (mean, 45) years during the same period. There was no significant difference between the older patients and younger controls regarding tumour grading (p=0.068, Chi squared test), stage, and pathological diagnosis.

RESULTS

Six patients had bone and 14 had soft-tissue sarcomas. Of the 6 bone sarcomas, 3 were malignant fibrous histiocytomas, 2 were osteosarcomas, and one was a chordoma; all were high grade, except for the chordoma. Of the 14 soft-tissue sarcomas, 9 were malignant fibrous histiocytomas, 3 were myxofibrosarcomas, one was a liposarcoma and one an extraskeletal osteosarcoma; all were high grade except for 2 of the myxofibrosarcomas and the liposarcoma. Of the 110 younger controls, 30 had bone and 80 had soft-tissue sarcomas; 44 were low grade and 66 were high grade. The 5-year survival rate was significantly lower in older patients than in younger controls (35% vs 65%, p=0.048). Regarding bone versus soft-tissue sarcomas, the 5-year survival rate was not significantly different among older patients (0% vs 52%, p=0.068) or younger controls 61% vs 66%, p=0.863). The difference was also not significant for older patients versus younger controls with bone sarcomas (0% vs 61%, p=0.284) or soft-tissue sarcomas (52% vs 66%, p=0.368), for older patients with high- versus low-grade sarcomas 17% vs 100%, p=0.314), for older patients with sarcomas located in the limbs versus the trunk (39% vs 38%, p=0.233), as well as for older patients versus younger controls with low-grade sarcomas (100% vs 92%, p=0.512) or high-grade sarcomas (17% vs 46%, p=0.269).

CONCLUSION

Survival rates tend to be lower in older patients with sarcomas, especially when the sarcoma is of bone and high grade.

Osteosarcoma in the elderly over 60 years: a multicenter study by the Japanese Musculoskeletal Oncology Group

BACKGROUND

Few studies have described the characteristics and prognostic factors of osteosarcoma patients aged over 60 years.

METHODS

The Japanese Musculoskeletal Oncology Group (JMOG) carried out a retrospective review of patients over the age of 60 years with osteosarcoma.

RESULTS

Only 12 patients had secondary osteosarcoma, with none associated with Paget's disease. The primary disease sites were the extremities in 63% and trunk in 33%. The overall survival was 42.8% and disease-free survival was 40.8% at 5 years in the high grade group. An univariate analysis indicated that significant poor prognostic factors for overall survival were axial location, lung metastasis at initial presentation, and absence of surgical treatment. Multivariate analysis revealed that a significant poor prognostic factor for overall survival was the absence of surgical treatment. Secondary osteosarcoma did not lower the overall or the disease-free survival in any group.

CONCLUSIONS

The current study indicates that the number of osteosarcoma patients over 60 years is increasing. The number of cases with secondary osteosarcoma over 60 years is relatively small in Japan, with no patients having osteosarcomas related to Paget's disease. Although there is a predilection for axial localization, surgical treatment has a significant impact on patient's prognosis.

Pediatric and adult osteosarcoma: comparisons and contrasts in presentation and therapy

Most data on osteosarcoma is derived from pediatric studies. Although the majority of adult patients with osteosarcoma are young adults, who might be treated in a similar fashion, experience derived from a slightly older population is helpful in directing therapy. We treated a series of 123 patients with osteosarcoma of the extremities with adriamycin and cisplatin as induction therapy. Adriamycin was infused intravenously at 90 mg/m2 over 96 h. Cisplatin was infused intra-arterially at 120-160 mg/m2 over 2-24 h. Sequential addition of methotrexate and methotrexate plus ifosfamide in subsequent cohorts improved the continuous relapse-free survival of poor responders such that overall survival improvement was noted in the group where therapy was modified by adding both agents to those with <90% tumor necrosis. Patients with chondroblastic osteosarcoma with poor necrosis had a trend towards improved continuous relapse-free survival compared with other patients with conventional osteosarcoma. Histologic variants of osteosarcoma except telangiectatic osteosarcoma had a worse prognosis than those with conventional osteosarcoma. The variants, especially dedifferentiated parosteal osteosarcoma and dedifferentiated well-differentiated intraosseous osteosarcoma are more common in adults than children, accounting for some of the inferior prognosis in adults. Older patients obviously cannot tolerate the doses of therapy given to children and young adults, again decreasing the chances of successful treatment. Patients with secondary osteosarcoma are often much older as are many with osteosarcomas of the pelvis and jaw. These tumors tend to be less responsive. An attempt to intensify therapy in poor-prognosis patients with a three-drug regimen of adriamycin, cisplatin, and ifosfamide with peripheral stem cell support was unsuccessful at prolonging relapse-free survival, and we no longer use that approach.