Osteoprotegerin blocks bone cancer-induced skeletal destruction, skeletal pain and pain-related neurochemical reorganization of the spinal cord

Bone cancer pain is common among cancer patients and can have a devastating effect on their quality of life. A chief problem in designing new therapies for bone cancer pain is that it is unclear what mechanisms drive this distinct pain condition. Here we show that osteoprotegerin, a secreted 'decoy' receptor that inhibits osteoclast activity, also blocks behaviors indicative of pain in mice with bone cancer. A substantial part of the actions of osteoprotegerin seems to result from inhibition of tumor-induced bone destruction that in turn inhibits the neurochemical changes in the spinal cord that are thought to be involved in the generation and maintenance of cancer pain. These results demonstrate that excessive tumor-induced bone destruction is involved in the generation of bone cancer pain and that osteoprotegerin may provide an effective treatment for this common human condition.

Malignancies in fibrous dysplasia

BACKGROUND

Malignancies in fibrous dysplasia are rare. Most cases have been published as single case reports. The role of radiation therapy in the occurrence of sarcoma in fibrous dysplasia is still controversial.

METHODS

The Mayo Clinic files were reviewed, including Mayo Clinic cases and consultation cases, to collect all cases of sarcomas arising in fibrous dysplasia.

RESULTS

Among 1122 cases with a histologic diagnosis of fibrous dysplasia, 28 cases of sarcoma were found. These 28 cases included 16 Mayo Clinic cases and 12 consultation cases. The sarcomas occurred in 19 cases of monostotic fibrous dysplasia and 9 cases of polyostotic disease (only 1 of Albright's syndrome). The most common histotype was osteosarcoma (19 cases), followed by fibrosarcoma (5 cases), chondrosarcoma (3 cases), and malignant fibrohistiocytoma (1 case). Of the 28 patients, 13 (46%) had received radiation therapy before the sarcoma developed. Most of these sarcomas occurred in the craniofacial bones (13 cases) or in the proximal femur (7 cases), followed by the humerus, pelvis, tibia, and scapula.

CONCLUSIONS

Prognosis was poor. Sarcomas may arise with or without radiation. Early diagnosis and adequate treatment may lead to improved prognosis.

Initial symptoms and clinical features in osteosarcoma and Ewing sarcoma

BACKGROUND

The time between the initial symptoms of osteosarcoma and Ewing sarcoma and the correct diagnosis and treatment is long. Over the last two decades, the prognosis for patients with these diseases has dramatically improved due to a new chemotherapy regimen. As a consequence, a limb-sparing operation has become an alternative to amputation. The aim of this study was to establish the initial symptoms and physical signs of osteosarcoma and Ewing sarcoma from the records of the first medical visit and to identify early characteristics of the diseases to shorten the delay to diagnosis.

METHODS

A group of patients with osteosarcoma or Ewing sarcoma was identified from the Swedish Cancer Register of patients thirty years old and younger. Records from the first medical visit due to symptoms related to the bone tumor were obtained for 102 patients with osteosarcoma and forty-seven patients with Ewing sarcoma.

RESULTS

Pain related to strain was reported by eighty-seven (85 percent) of the patients with osteosarcoma and thirty (64 percent) of those with Ewing sarcoma, but only twenty-one (21 percent) of the patients with osteosarcoma and nine (19 percent) of those with Ewing sarcoma reported pain at night. Forty-eight (47 percent) of the patients with osteosarcoma and twelve (26 percent) of those with Ewing sarcoma related the onset of symptoms to minor trauma occurring around the same time. A palpable mass was noted in forty (39 percent) of the patients with osteosarcoma and sixteen (34 percent) of those with Ewing sarcoma at the first visit, and in most cases the tumor diagnosis was suspected. There was a broad spectrum of misdiagnoses; the most common was tendinitis, which was the initial diagnosis in thirty-two (31 percent) of the patients with osteosarcoma and ten (21 percent) of those with Ewing sarcoma. The doctor's delay (the period from the first medical visit due to the symptoms to the correct diagnosis) was longer for Ewing sarcoma than for osteosarcoma (nineteen weeks and nine weeks, respectively; p < 0.0001).

CONCLUSIONS

An initial symptom of both osteosarcoma and Ewing sarcoma was pain, which was intermittent and often related to strain but not frequently felt at night. A history of trauma was common, but the clinical course often diverged from what was expected from trauma. The clinical course of osteosarcoma and particularly of Ewing sarcoma was not steadily progressive but intermittent, which often misled the doctor into believing that the condition was temporary. The most important clinical feature was a palpable mass, which was noted in more than one-third of the patients at the first visit. This finding emphasizes that a thorough physical examination is absolutely necessary.

Therapeutic Relevance of Osteoprotegerin Gene Therapy in Osteosarcoma: Blockade of the Vicious Cycle between Tumor Cell Proliferation and Bone Resorption

Osteosarcoma is the most frequent primary bone tumor that develops mainly in the young, the median age of diagnosis being 18 years. Despite improvement in osteosarcoma treatment, survival rate is only 30% at 5 years for patients with pulmonary metastases at diagnosis. This warrants exploration of new therapeutic options, and among them, osteoprotegerin (OPG), a naturally occurring protein that inhibits bone resorption, is very promising in blocking the vicious cycle between bone resorption and tumor proliferation that takes place during tumor development in bone site. As OPG binds and inhibits the activity of tumor necrosis factor-related apoptosis-inducing ligand, the truncated form of murine OPG 1-194 was used. The cDNA encoding OPG was administered by gene transfer using replication-defective adenoviral vector or was associated with an amphiphilic polymer in two models of rodent osteosarcoma. In both models, OPG gene transfer was effective in preventing the formation of osteolytic lesions associated with osteosarcoma development, in reducing the tumor incidence and the local tumor growth, leading to a 4-fold augmentation of mice survival 28 days postimplantation. On the contrary, OPG did not prevent the development of pulmonary metastasis alone, suggesting that bone environment is necessary for OPG therapeutic efficacy. Because OPG has no direct activity on osteosarcoma cells in vitro (cell binding, cell proliferation, apoptosis, or cell cycle distribution), we show that OPG exerts indirect inhibitory effect on tumor progression through the inhibition of RANKL whose production is enhanced in bone tumor environment, leading to osteolysis inhibition as reflected by osteoclast number decrease.

Second tumors in nonirradiated bilateral retinoblastoma

We reviewed the records of 1,323 patients with retinoblastoma treated here between 1922 and 1978. Twenty-eight patients underwent bilateral enucleation alone and received no additional treatment for their advanced tumors. Of the 28 patients, 22 (92%) survived. Four patients were lost to follow-up, and two died of metastatic retinoblastoma. Of 22 survivors of bilateral retinoblastoma treated with enucleation alone, three developed second tumors at a mean of 15.3 years after bilateral enucleation. One patient developed a rhabdomyosarcoma in the left temple region, the second patient developed an osteogenic sarcoma of the right femur, and the third developed a malignant melanoma of the left thigh. All three patients died of their disease. The incidence of second tumors in patients who survived bilateral retinoblastoma treated without radiation was 14% (three patients), which is comparable to a series previously reported in which patients were treated with enucleation and irradiation.

Osteosarcoma in Paget's disease of bone

Paget's disease of bone (PDB) is a focal disorder of bone metabolism first described by Sir James Paget in 1876. It is presumed benign in nature and mediated by abnormal osteoclast function. The incidence of osteosarcomas complicating PDB is estimated at <1%. These cancers occur mostly in persons with long-standing, polyostotic disease and affect patients in their seventh decade or when osteosarcoma is remarkably rare in the general population. Epidemiological studies suggest that this late peak of osteosarcomas is absent in regions where Paget's is infrequently reported. Whereas PDB has a predilection for the axial skeleton, skull, femurs, and tibias, pagetic osteosarcoma tend to spare the spine, and are reported more commonly in the pelvis, femur, humerus, and skull. A molecular basis for the association of osteosarcoma with Paget's disease is unclear. These osteosarcomas are osteogenic in origin, consistently arise in sites of pagetic bone, and may present as metachronous, multifocal lesions. On histopathology, the lesions are usually osteoblastic, and the tumor phenotype is sometimes characterized as an exaggerated, chaotic form of the accelerated bone remodeling that characterizes PDB. New insights from the biology of adolescent osteosarcomas, VCP and SQSTM1 mutations now defined in patients with Paget's disease, and emerging evidence that stromal lesions are present in patients with Paget's disease are changing the way we think about the pathogenesis of PDB and the rare complication of pagetic osteosarcomas.

Telangiectatic osteogenic sarcoma: a clinicopathologic study of 124 patients

One hundred-twenty-four patients with this rare and special variant of osteogenic sarcoma were treated at Memorial Sloan-Kettering Cancer Center from 1921 through 1979, representing 11% of all of osteogenic sarcomas. The lesions were predominantly lytic, destructive tumors with only minimal sclerosis on roentgenograms and soft as well as cystic on gross examination. Histologically, aneurysmally dilated spaces lined or traversed by sarcoma cells producing osteoid were noted. The differential diagnosis both radiographically and histologically included several benign lesions like aneurysmal bone cyst and giant cell tumor, among many others. It was found that telangiectatic osteogenic sarcoma is relatively frequent in the femoral diaphysis and in the distal end of the femur. Twenty-nine percent of the patients present with pathologic fracture, or this develops later. Age and sex distribution, or clinical signs or symptoms were those of ordinary osteogenic sarcomas. No differences in survival rates were found in lesions that were purely lytic or those with minimal sclerosis. Similarly, no differences in survival were noted when comparing patients with telangiectatic or ordinary osteogenic sarcoma. As a matter of fact, definite increase in survival was found in patients treated since 1975 with preoperative multidrug chemotherapy employing high-dose methotrexate. Adriamycin, and the combination of bleomycin, cyclophosphamide, and dactinomycin.

Aneurysmal bone cyst secondary to other osseous lesions. Report of 57 cases

Fifty-seven aneurysmal bone cysts which were associated with or secondary to other lesions of bone are reported. The most common associations were with solitary or unicameral bone cyst, and with osteoclastoma. Other associated lesions included osteosarcoma, nonosteogenic fibroma, osteoblastoma, hemangioendothelioma, and hemangioma of bone. Five aneurysmal bone cysts were secondary to fracture or other bone trauma.

The wrickkened pathways of FGF23, MEPE and PHEX

The last 350 years since the publication of the first medical monograph on rickets (old English term wrickken) (Glisson et al., 1651) have seen spectacular advances in our understanding of mineral-homeostasis. Seminal and exciting discoveries have revealed the roles of PTH, vitamin D, and calcitonin in regulating calcium and phosphate, and maintaining healthy teeth and skeleton. However, it is clear that the PTH/Vitamin D axis does not account for the entire picture, and a new bone-renal metabolic milieu has emerged, implicating a novel set of matrix proteins, hormones, and Zn-metallopeptidases. The primary defects in X-linked hypophosphatemic rickets (HYP) and autosomal-dominant hypophosphatemic rickets (ADHR) are now identified as inactivating mutations in a Zn-metalloendopeptidase (PHEX) and activating mutations in fibroblast-growth-factor-23 (FGF23), respectively. In oncogenic hypophosphatemic osteomalacia (OHO), several tumor-expressed proteins (MEPE, FGF23, and FRP-4) have emerged as candidate mediators of the bone-renal pathophysiology. This has stimulated the proposal of a global model that takes into account the remarkable similarities between the inherited diseases (HYP and ADHR) and the tumor-acquired disease OHO. In HYP, loss of PHEX function is proposed to result in an increase in uncleaved full-length FGF23 and/or inappropriate processing of MEPE. In ADHR, a mutation in FGF23 results in resistance to proteolysis by PHEX or other proteases and an increase in half-life of full-length phosphaturic FGF23. In OHO, over-expression of FGF23 and/or MEPE is proposed to result in abnormal renal-phosphate handling and mineralization. Although this model is attractive, many questions remain unanswered, suggesting a more complex picture. The following review will present a global hypothesis that attempts to explain the experimental and clinical observations in HYP, ADHR, and OHO, plus diverse mouse models that include the MEPE null mutant, HYP-PHEX transgenic mouse, and MEPE-PHEX double-null-mutant.

Osteogenic sarcoma associated with Paget's disease of bone. A clinicopathologic study of 65 patients

Among 1177 osteogenic sarcoma patients diagnosed and treated at Memorial Hospital, 65 (5.5%) were associated with either monostotic or polyostotic Paget's disease. The overall median age was 64 years (range, 39-82 years). In those patients older than 40 years of age, the frequency of sarcomatous transformation rose to 27%. There were slightly more men (55%) than women. The most common skeletal sites were the pelvic bones (34%), the humerus (22%), the femur (19%), and the craniofacial bones (14%). Unrelenting pain and tender swelling were the most common presenting symptoms (85%), with pathologic fracture in 14 (22%) patients. In two-thirds of the cases, the radiographic presentation was that of a lytic destructive lesion; while in the others it showed a sclerotic, mixed, or permeative character. In almost one-half of the cases, the histologic appearance of the osteogenic sarcomas was either fibrohistocytomatous or osteoblastic. In spite of radical surgical amputations, only three patients survived longer than 5 years. The prognosis of Paget's sarcoma is significantly less favorable than in osteogenic sarcoma arising de novo in patients of comparable age.

Osteogenic sarcoma associated with Diamond-Blackfan anemia: a report from the Diamond-Blackfan Anemia Registry

PURPOSE

Diamond-Blackfan anemia (DBA) is a congenital pure red cell aplasia, usually presenting in infancy or early childhood. A review of the literature strongly supports a predisposition to hematopoietic malignancy. Recently, solid tumors have been reported, some attributable to hemosiderosis and/or androgen therapy. Two cases of osteogenic sarcoma have also been documented. An analysis from the Diamond-Blackfan Anemia Registry was performed to evaluate the cancer risk in patients with DBA.

METHODS

The Diamond-Blackfan Anemia Registry of North America (DBAR) is a comprehensive database of patients with DBA enrolled, after informed consent, through outreach to pediatric hematologists and family groups. The patients and/or their families complete a detailed questionnaire, and a review of medical records and telephone interviews are performed to complete and clarify the information provided.

RESULTS

Of the 354 patients registered in the DBAR, there were six patients meeting the accepted diagnostic criteria for DBA who were found to have malignancies. Three patients had osteogenic sarcoma diagnosed, one with myelodysplastic syndrome, one with colon carcinoma, and one with a soft tissue sarcoma.

CONCLUSION

There appears to be an association of osteogenic sarcoma with DBA. A young age at presentation may be a feature of DBA-associated osteogenic sarcoma. Because of the immaturity of the database, the actuarial risk for osteogenic sarcoma and other cancers in individuals with DBA cannot be ascertained. Speculation is made regarding the nature of the molecular defect leading to the association of DBA and osteogenic sarcoma.

Sarcoma complicating Paget's disease of bone. A clinicopathological study of 62 cases

Out of 21 900 cases filed at the Latin-American Registry of Bone Pathology between April 1940 and July 1981, there were 987 with Paget's disease (4.51 per cent); 62 of these (6.28 per cent) were complicated by sarcoma and two were associated with giant-cell tumours of bone (osteoclastoma) without signs of malignancy. There was a slight predominance of men and the ages ranged from 45 to 87 years, with an average of 66 years. The most frequent sites were the femur (23 cases), the humerus (nine), the pelvis (10), and the tibia (nine). The low incidence of vertebral involvement (five cases) is noteworthy and is in sharp contrast to uncomplicated Paget's disease. The most common tumour type was osteosarcoma (39 cases), followed by fibrosarcoma (15 cases); other varieties (chondrosarcoma, malignant fibrous histiocytoma and reticulum-cell sarcoma) were much rarer. Most of the sarcomata occurred when the Paget's disease was polyostotic. Tumours often developed simultaneously, or at short time intervals, in the same or different bones; these bones had, in all cases, been affected by Paget's disease. The histological features of the osteosarcomata were characteristic, with large numbers of osteoclast giant cells, alternating with atypical osteoblasts, thus exaggerating the anarchic remodelling process of Paget's disease. The neighbouring areas of the pagetic bone showed an increased number of osteoclasts. These facts suggest a possible pathogenetic relationship between sarcoma and Paget's disease; the possibility of both processes having a viral aetiology is discussed.

Improved MR imaging for patients with metallic implants

Pediatric oncology patients with large metallic prostheses were imaged with one of two MR imaging techniques: 1) the "tilted view-angle" technique, 2) or a higher readout bandwidth technique. The tilted view-angle method uses an additional gradient in the slice selection direction during readout. The high bandwidth technique increases the readout bandwidth and shortens the echo time (TE). High bandwidth and short echo times were implemented in both T(1)-weighted (T(1)W) turbo spin echo and turbo short tau inversion recovery (STIR) sequences. Both imaging techniques reduced the size of metal-induced image artifacts. The tilted view-angle method reduced the artifact to a greater degree but had inherent shortcomings. The reformatted images were blurred and shifted. The area of interest was often moved outside of the field of view, unless parameters were adjusted on the basis of a pre-scan calculation. The high readout bandwidth, short echo technique required no special preparation and reduced metal artifacts without image blurring. The combination of high-bandwidth, shorter echo turbo STIR and T(1)W turbo spin echo sequences with subtraction of pre- from post-contrast images allowed effective fat suppression without local field inhomogeneity affects. This greatly improved our ability to evaluate suspected disease near metallic implants in pediatric cancer patients.

Sarcoma in Paget disease of bone: clinical, radiologic, and pathologic features in 22 cases

The clinical, radiologic, and histologic features of 22 cases of Paget sarcoma were reviewed to determine in which patients with Paget disease these tumors are most likely to develop and what radiologic findings suggest the diagnosis. Clinical findings at presentation included pain and/or a mass (11 patients), pathologic fracture (seven), and neurologic symptoms (four). Survival time in 20 patients ranged from 5 days to 2.5 years. Two patients were lost to follow-up: one at 2 years and one at 8 years. There were 16 high-grade osteosarcomas, three chondrosarcomas, two fibrosarcomas, and one malignant fibrous histiocytoma. The most common site was the femur. Tumors also were observed in unusual sites. In one case of multifocal osteosarcoma, the tumor involved only pagetic bone. In 15 patients, Paget disease was polyostotic, clinically significant, and had been documented previously. In four patients, a sarcoma developed near the site of a fracture that had occurred between 2 months and 15 years previously. All cases showed radiologic evidence of a destructive lesion; other findings included a mass and evidence of tumor mineralization. Periosteal reaction was not observed. All but one tumor developed in a site of osteoblastic or mixed osteoblastic and lytic Paget disease. Our results suggest that sarcomas can develop in any part of any bone affected by Paget disease but are more likely to occur with advanced disease and to present with a destructive lesion without periosteal reaction.

Second malignant neoplasms in long-term survivors of osteosarcoma: Memorial Sloan-Kettering Cancer Center Experience

BACKGROUND

The authors investigated the incidence and relative risk of secondary malignant neoplasms in long-term survivors of osteosarcoma.

METHODS

A comprehensive list of 509 patients with primary osteosarcoma treated at our institution between February 1973 and March 2000 was identified. All study patients received chemotherapy and/or surgery on one of six different protocols (T4, 5, 7, 10, 12, and CCG-7921/POG-9351). Chemotherapy was scheduled for up to 40 weeks with some variations in the actual treatment period and consisted of various combinations of the following agents: high-dose methotrexate, doxorubicin, bleomycin, cyclophosphamide, dactinomycin, vincristine, cisplatin, and ifosfamide.

RESULTS

Secondary malignant neoplasms (SMN) occurred in 14 of 509 patients. Only one had pulmonary metastasis at diagnosis and subsequent multiple recurrences that required thoracotomies and further modification of the chemotherapy regimen. The median age at diagnosis for osteosarcoma was 16.6 years (range, 3.1-74.4 years). The median follow-up was 5.2 years (range, 0.1-25.0 years). The time interval from diagnosis of the primary osteosarcoma to the development of SMN was 1.3-13.1 years (median, 5.5; 95% confidence interval [CI], 3.6-9.6). The most common SMN occurred in the central nervous system (n = 4): anaplastic glioma, meningioma, high-grade glioma, and maxillary astrocytoma. There were two cases of acute myeloid leukemia and one case each of myelodysplastic syndrome, non-Hodgkin lymphoma, high-grade pleomorphic sarcoma, leiomyosarcoma, fibrosarcoma, breast carcinoma, and mucoepidermoid carcinoma. The overall 5 and 10-year cumulative incidences of SMNs were 1.4% +/- 1.1% and 3.1% +/- 1.8%. The standardized incidence ratio was 4.6 (95% CI, 2.53-7.78, P = 0.00001) for the cohort and 3.64 (95% CI, 1.82-6.52, P = 0.0007) when patients with a history of retinoblastoma or Rothmund-Thomson syndrome were excluded.

CONCLUSIONS

The overall incidence of secondary malignancies in long-term survivors of osteosarcoma was significantly higher than the expected incidence of cancer in the general population. However, the standardized incidence ratios were much lower than those reported for Hodgkin disease and retinoblastoma. Although additional follow-up is warranted, the successes of current treatment regimens consisting of intensive, high-dose chemotherapy in combination with topoisomerase II inhibitors outweigh the risks.

Pathologic fracture in osteosarcoma. Impact of chemotherapy on primary tumor and survival

Twenty patients with osteosarcoma and pathologic fractures were treated with a chemotherapeutic regimen consisting of cis-diamminedichloroplatinum-II (CDP), Adriamycin (ADR) (doxorubicin) and high-dose methotrexate with citrovorum factor "rescue" (MTX-CF). Before the introduction of the regimen, the primary tumor in two patients was treated by immediate amputation and in 13 with preoperative intra-arterial CDP. Among these 13 patients, responses (healing) were observed in 11 (one required the addition of radiation therapy). In three patients, the responses were so dramatic that, at their request, surgery was deferred and treatment exclusively with chemotherapy was instituted. Based on this experience, treatment exclusively with chemotherapy was also administered to an additional five patients who were admitted without pathologic fractures. In the course of such treatment, pathologic fractures also developed; notwithstanding, chemotherapy was maintained and healing also occurred. One of the 20 patients had pulmonary metastases at diagnosis; these were resected after treatment and pathologic examination revealed no evidence of viable tumor. The remaining 19 patients were free of pulmonary metastases but these later developed in seven patients. These data were compared to a historical control series in which 16 of 21 patients with pathologic fractures developed pulmonary metastases. Three of the chemotherapy treated patients died of nonosteosarcoma related causes (leukemia, generalized varicella, and a metabolic complication). Overall, survival was improved in the chemotherapy treated patients as compared to the historical control series: 10 of 20 versus 6 of 21, respectively. Pathologic fractures in osteosarcoma may heal under treatment with chemotherapy, which also has a favorable impact on the eradication of pulmonary metastases and survival.

Pathologic fractures in children

Fractures through bone tumors are often difficult to treat. We reviewed our combined experience with this problem in children, as well as the existing literature, to formulate management guidelines. For this study, prospective databases (1987 to 2002) from three referral centers were screened for pathologic fractures occurring under the age of 14 years. One hundred five patients presented with fracture through unicameral bone cyst, nonossifying fibroma, fibrous dysplasia, aneurysmal bone cyst and osteosarcoma. Seventeen patients were excluded. The most common primary locations were the proximal humerus and proximal femur. Pathologic fracture through nonossifying fibroma had the best outcome; union occurred with nonsurgical treatment in all cases. Unicameral bone cyst required surgical treatment to avoid persistence of the cyst and refracture. However fracture healing was predictable without surgical treatment. Proximal femoral lesions tended to heal in malunion if not fixed surgically. Aneurysmal bone cyst required surgical treatment for the lesion to heal and to allow the fracture to heal as well. Percutaneous sclerotherapy may be the treatment of choice for many of these lesions. Fibrous dysplasia allows fracture healing with nonoperative therapy. Progressive deformity requires followup and surgical correction. Malignant lesions presenting a pathologic fracture are best managed by initial nonoperative therapy during investigation and neoadjuvant therapy when possible, followed by definitive treatment.

The saddle prosthesis in pelvic primary and secondary musculoskeletal tumors: functional results at several postoperative intervals

The first purpose of this study was to evaluate the saddle prosthesis in patients with periacetabular tumors in terms of the functional results obtained after several postoperative intervals. The second purpose was to evaluate the complications and how they might be prevented in the future. Functional results according to the MSTS functional rating system were evaluated at several postoperative intervals in 15 patients treated with internal hemipelvectomy and reconstruction with the saddle prosthesis because of periacetabular primary (n = 9) or secondary (n = 6) malignancies. All complications were evaluated. Three months postoperatively, 7/9 patients with a primary tumor and 2/4 patients with a secondary tumor were able to walk outside without pain. Median functional results 3 and 6 months postoperatively were 40% and 50%, respectively. Deep infection occurred in 4 patients and fracture of the iliac remnant in 2. Heterotopic ossifications along the interpositional component were seen in 5 patients, but they did not negatively influence the functional outcome. Three (relative) contraindications to reconstruction with the saddle prosthesis could be ascertained: osteoporosis, extended involvement of the iliac wing by tumor, and insufficient soft-tissue quality after previous procedures. (Short-term) functional results after reconstruction with the saddle prosthesis are satisfactory if the above-mentioned contraindications are taken into consideration.

P2X7 receptor-deficient mice are susceptible to bone cancer pain

The purinergic P2X7 receptor is implicated in both neuropathic and inflammatory pain, and has been suggested as a possible target in pain treatment. However, the specific role of the P2X7 receptor in bone cancer pain is unknown. We demonstrated that BALB/cJ P2X7 receptor knockout (P2X7R KO) mice were susceptible to bone cancer pain and moreover had an earlier onset of pain-related behaviours compared with cancer-bearing, wild-type mice. Furthermore, acute treatment with the selective P2X7 receptor antagonist, A-438079, failed to alleviate pain-related behaviours in models of bone cancer pain with and without astrocyte activation (BALB/cJ or C3H mice inoculated with 4T1 mammary cancer cells or NCTC 2472 osteosarcoma cells, respectively), suggesting that astrocytic P2X7 receptors play a negligible role in bone cancer pain. The results support the hypothesis that bone cancer pain is a separate pain state compared with those of neuropathic and inflammatory pain. However, the recent discovery of a P2X7 receptor splice variant expressed in the knockout mice used for this study complicates the interpretation of the results. The P2X7 splice variant receptor was detected in the spinal cord but not in osteoclasts of the P2X7R KO mouse. Further experiments are needed to elucidate the exact role of the P2X7 receptors in bone cancer pain.

Targeted radiotherapy of osteosarcoma using 153 Sm-EDTMP. A new promising approach

We report a case where targeted radionuclide therapy using 153Sm-EDTMP gave substantial palliative effect. A 35-year-old male with a primary osteosarcoma located in the first lumbar vertebra relapsed with progressive back pain after conventional treatment modalities had failed. He became bedridden, and developed paraparesis and impaired bladder function. On a diagnostic bone-scan intense radioactivity was localized in the tumor. He therefore was given 153Sm-EDTMP treatment twice, 8 weeks apart, 35 and 32 MBq/kg body weight respectively. After a few days the pain was significantly relieved and by the second radionuclide treatment the pareses subsided. For six months he was able to be up and about without any neurological signs or detectable metastases. Eventually, however, he experienced increasing local pain, developed paraparesis, was re-operated but died 4 months later. The dramatic transient improvement observed in this case warrants further exploration using 153Sm-EDTMP as a boost technique, supplementary to conventional external radiotherapy.

Analgesic effects of capsazepine and resiniferatoxin on bone cancer pain in mice

In the present paper, we describe the analgesic effects induced by the transient receptor potential vanilloid type 1 (TRPV1) antagonist, capsazepine, and the TRPV1 agonist, resiniferatoxin, on the thermal hyperalgesia induced by the presence of a tibial osteosarcoma or an inflammatory process in mice. The administration of capsazepine abolished the osteosarcoma-induced hyperalgesia at a dose range (3-10 mg/kg; s.c.) ineffective to inhibit the hyperalgesia elicited by the intraplantar administration of complete Freund's adjuvant (CFA). In contrast, the administration of resiniferatoxin (0.01-0.1 mg/kg; s.c.) inhibited both the osteosarcoma- and the CFA-induced hyperalgesia. Remarkably, a single dose of resiniferatoxin abolished the osteosarcoma-induced hyperalgesia for several days and completely prevented the instauration of thermal hyperalgesia when administered at the initial stages of osteosarcoma development. The potential of drugs acting through TRPV1 for the management of some types of bone cancer pain is proposed.

Bone sarcomas in Paget disease

The most serious complication of Paget disease is the development of sarcoma. Forty-one cases of bone sarcoma in Paget disease, which represented our institution's entire experience, were reviewed. The relative frequency of sarcomatous degeneration was 0.9%. Histologically, 35 of 41 lesions were osteogenic sarcomas, and six were fibrosarcomas. The distribution of lesions was similar to that expected with uncomplicated Paget disease, except for a disproportionately high number of lesions in the humerus; only one lesion involved the vertebrae. The tumors were categorized radiographically as lytic, mixed, and sclerotic, in descending order of frequency. The vast majority of lesions occurred in the pelvis, humerus, and femur. Overall prognosis for these patients was poor, with a five-year survival of 8%. Finding areas of cortical destruction is particularly useful in the detection of malignant degeneration. The radiologist must maintain a high index of suspicion when evaluating radiographs of patients with Paget disease, especially of those who present with pain or a palpable mass.