Frequent genomic abnormalities at TWIST in human pediatric osteosarcomas.

The identification of genes as markers for chromosome aberrations in specific tumors might facilitate oncogenesis mechanism comprehension, cancer detection, prediction of clinical outcomes, and response to therapy. Previous physiologic and oncologic data identified the TWIST gene as a marker for mesodermal derivative and bone tissue differentiation, but its contribution to bone malignancies has not been investigated. In the present study, search for genomic alterations in high-grade pediatric osteosarcomas was focused on the 7p21 region, and more specifically on the TWIST gene. In a cohort of 74 patients, we observed by allelotyping that 31 of 68 informative tumors were rearranged at the TWIST locus. Among them, analysis by quantitative PCR (QPCR) revealed that, surprisingly, mostly deletions (22/68), but also amplifications (9/68), of the TWIST gene were detected. Furthermore, deletions at TWIST were statistically correlated to other molecular abnormalities, like alterations at the APC or c-kit loci, as well as to clinical features such as a poor outcome. This work shows that the TWIST gene seemed to be involved in high-grade pediatric osteosarcomas and is a new marker with a possible initial predictive value.

Prognostic significance of allelic imbalance at the c-kit gene locus and c-kit overexpression by immunohistochemistry in pediatric osteosarcomas.

PURPOSE: Since the recent development of biologic agents targeting oncogenes, increasing attention has been focused on determining the role of tyrosine kinase receptors in the pathogenesis of tumors. Our study was designed to investigate the status of region 4q12, which contains the candidate gene c-kit, and the expression of c-kit by immunohistochemistry (IHC). PATIENTS AND METHODS: Paired blood and biopsy specimens of 68 children treated for high-grade primary osteosarcomas were collected. Microsatellite analysis at two genomic sites containing c-kit gene was performed on paired DNA using a sensible fluorescent polymerase chain reaction technology. To confirm the DNA data, we studied c-kit protein expression by IHC in 56 available paraffin-embedded tumor tissues. RESULTS: The frequency of allelic imbalance (AI) at locus 4q12 was 39% in the overall population. In agreement with previous studies, we did not detect microsatellite instability, allowing us to hypothesize that this pathway is not implicated. Furthermore, the normal status at locus 4q12 was associated with a significantly better survival in the whole osteosarcoma population (P = .05). IHC overexpression of c-kit was concordant in all cases presenting an AI. However, normal status at locus 4q12 was correlated to an absence of c-kit protein expression in 19 (65.5%) of 29 informative cases. CONCLUSION: Allelotyping of locus 4q12, which contains the c-kit gene, could help pediatric osteosarcoma prognostic screening and showed a strong correlation with overexpression of c-kit protein. These results allowed us to hypothesize that, in some cases, a mutation of c-kit gene could lead to a protein overexpression.

Analysis of risk factors for myelodysplasias, leukemias and death from infection among patients with congenital neutropenia. Experience of the French Severe Chronic Neutropenia Study Group.

BACKGROUND AND OBJECTIVES: The two main complications of severe chronic neutropenia are fatal sepsis and myelodysplasia/acute leukemia (MDS/AL). Granulocyte colony-stimulating factor (G-CSF) therapy has significantly reduced the frequency and severity of infections, but its possible influence on the risk of malignancy is not known. DESIGN AND METHODS: The French Severe Chronic Neutropenia (SCN) Registry has prospectively collected data since 1994 on 231 patients with various forms of SCN, namely severe congenital neutropenia (n=101), cyclic neutropenia (n=60), glycogen storage disease type Ib (GSDIb) (n=15) and Shwachman-Diamond syndrome (SDS)(n=55). The median overall follow-up is 11.1 years. Parameters of exposure to G-CSF therapy, such as the time averaged dose, follow up after first use of G-CSF, and the cumulative dose, have been recorded. RESULTS: Eight septic deaths occurred, of which 6 among patients with severe congenital neutropenia and 2 in patients with cyclic neutropenia; none of these 8 patients was receiving G-CSF therapy. No septic deaths occurred during G-CSF therapy. Thirteen cases of MDS/AL were recorded. The cumulative incidence of MDS/AL was 2.7% (SD 1.3%) at 10 years and 8.1% (SD 2.7%) at 20 years. INTERPRETATION AND CONCLUSIONS: Risk factors for MDS/AL were the diagnostic category, the severity of neutropenia, younger age at diagnosis, and strong exposure to G-CSF. MDS/AL only occurred in patients with severe congenital neutropenia and SDS. Owing to their particular susceptibility to infections, patients with severe congenital neutropenia had the strongest exposure to G-CSF; the risk of leukemia increased with the degree of G-CSF exposure in this subgroup.

Progression-free survival in children with optic pathway tumors: dependence on age and the quality of the response to chemotherapy--results of the first French prospective study for the French Society of Pediatric Oncology.

PURPOSE: To evaluate a strategy aimed at avoiding radiotherapy during first-line treatment of children with progressive optic pathway tumors (OPT), by exclusively administering multiagent chemotherapy during 16 months. PATIENTS AND METHODS: Between 1990 and 1998, 85 children with progressive OPT were enrolled onto this multicenter nationwide trial. Chemotherapy alternating procarbazine plus carboplatin, etoposide plus cisplatin, and vincristine plus cyclophosphamide was given every 3 weeks. At the time of relapse or progression, second-line chemotherapy was authorized before recourse to radiotherapy. RESULTS: Objective response rate (partial response [PR] + complete response [CR]) to chemotherapy was 42%. Five-year progression-free survival (PFS) and overall survival rates were 34% and 89%, respectively. The 5-year radiotherapy-free survival rate was 61%. In the multivariate analysis of the 85 patients that entered onto the study, factors associated with the risk of disease progression were age younger than 1 year at diagnosis (P =.047) and absence of neurofibromatosis type 1 (P =.035). In the multivariate analysis of the 74 patients that remained on study after the first cycle of chemotherapy, factors associated with the risk of disease progression were age younger than 1 year at diagnosis (P =.0053) and no objective response to chemotherapy (P =.0029). Three-year PFS was 44% in infants < or = 1 year versus 66% in children older than 1 year. Three-year PFS was 53% in the absence of an objective response to chemotherapy versus 68% after a PR or CR. CONCLUSION: A significant proportion of children with OPT can avoid radiotherapy after prolonged chemotherapy. Deferring irradiation with chemotherapy protocols did not compromise overall survival of the entire population or visual function.

The urinary bladder: An extremely rare location of pediatric neuroblastoma.

Pediatric malignant tumors in the urinary bladder are rare with a high prevalence of rhabdomyosarcomas. A 15-month-old patient was referred to the authors' center because of a urinary bladder tumor. Imaging studies disclosed a solid pelvic mass in the dome of the bladder confirmed by a cystoscopy. Surprisingly, the biopsy done during this procedure confirmed a neuroblastoma with a favorable Shimada classification. This tumor had no bad prognostic factors. But, vessel compression and local infiltration led to delayed surgery, and neoadjuvant chemotherapy was initiated. After chemotherapy, a complete surgical resection was accomplished. Currently, this patient is in complete continuous remission. Only 5 other cases have been reported. Thus, urinary neuroblastoma seems to be a very rare pediatric tumor, but it should be considered in the differential diagnoses of urinary bladder tumor.

Neuroblastoma in adolescents.

BACKGROUND: Less than 5% of neuroblastomas are diagnosed in adolescent patients. Previous studies of patients who were treated with less intensive chemotherapy regimens relative to currently available regimens suggested that adolescents survived longer than younger children, and this finding was related to a lack of myc-N amplification. Those reports prompted the authors to study a cohort of adolescent patients who had been included in more recent trials. METHODS: The authors investigated the presentation, treatment, and outcome in 28 adolescent patients who were enrolled in studies of the French Society of Pediatric Oncology during the period from 1987 to 1999 and who were older than age 10 years at the time they were diagnosed with neuroblastoma. The results were used to compare this subpopulation with a control group of children. RESULTS: None of the six patients with Stage I-II disease either developed recurrent disease or died. At 5 years, disease progression was high (progression-free survival [PFS], 28%) for the 9 adolescents with Stage III disease, but so was survival (overall survival [OS], 86%). The 13 adolescent patients with metastatic neuroblastoma had very poor outcomes (PFS, 18%; OS, 27%). Despite intensive therapy, advanced neuroblastoma appeared to carry a poorer prognosis in adolescent patients compared with children, although patients with Stage III disease had a more indolent course. No difference was found between adolescent patients and children regarding the clinical presentation, treatment schedule, or doses and tolerance of chemotherapy. The incidence of elevated urinary catecholamine metabolite secretion was lower in adolescents compared with children. CONCLUSIONS: Adolescent patients with advanced neuroblastoma had less favorable outcomes compared with children, even if survival in adolescents with Stage III disease seemed longer.