Comparative genomic hybridization of postirradiation sarcomas

Distinct genomic landscapes in radiation-associated angiosarcoma compared with other radiation-associated sarcoma histologies

MYC amplifications have been frequently detected in radiation (RT)-associated angiosarcomas (ASs) by low-resolution molecular methods. However, large-scale next-generation sequencing (NGS) studies to investigate the genomic landscape of RT-AS are scarce, particularly compared with other RT-associated sarcomas. We performed a detailed comparative genomic investigation of RT-AS versus other RT-associated histotypes, as well as sporadic sarcomas with similar histologies. Our institutional targeted DNA-NGS assay database was searched for RT-associated sarcomas. Clinical outcome data, pathologic diagnosis, and the types and frequencies of genomic alterations, including single nucleotide variants (SNVs) and copy number alterations (CNAs), were analyzed. The cohort consisted of 82 patients, 68 (83%) females and 14 (17%) males, aged 37-88 (mean 64) years. Forty-four RT-ASs (38 from breast) and 38 RT sarcomas of other histologies, including 12 malignant peripheral nerve sheath tumors (RT-MPNSTs), 14 undifferentiated pleomorphic sarcomas (RT-UPSs), and 12 osteosarcomas (RT-OSs), were included. Median time intervals from radiation to initial diagnosis in RT-AS (8.0 years) were significantly lower than those in RT-MPNST and RT-UPS (12.5 and 18.5 years), respectively. Each RT-sarcoma histotype harbored distinct mutations and CNAs. RT-associated AS had more frequent MYC, FLT4, CRKL, HRAS, and KMT2D alterations than sporadic AS (enriched in TP53, KDR, ATM, ATRX), whereas the mutational landscapes of MPNST, UPS, and OS were similar in both RT and non-RT settings. CDKN2A/B deletions and TP53 alterations were infrequent in RT-AS compared with other RT sarcomas. Among RT sarcomas, RT-AS harbored the lowest fraction of genome altered (FGA), while RT-MPNST showed the highest FGA. RT-AS had the lowest insertion:SNV and deletion:SNV ratios, while RT-UPS had the highest. The predominant mutational signatures were associated with errors in DNA repair and replication. In conclusion, RT-AS has a distinct genomic landscape compared with other RT sarcomas and sporadic AS. Potential molecular targets for precision medicine may be histotype-dependent. © 2023 The Pathological Society of Great Britain and Ireland.

Radiation-Induced Sarcoma: A Retrospective Population-Based Study Over 34 Years in a Single Institution

AIMS

About a half of all cancer patients receive radiotherapy as part of their oncological treatment. Because of the carcinogenic effect of ionising radiation, there is a rare, but definite, risk of developing secondary malignancies, including sarcomas. The aim of this retrospective study was to describe the prevalence, patient and tumour characteristics, as well as prognosis and outcome, of patients with radiation-induced sarcomas (RIS) in a cohort of patients treated in the Sarcoma Centre at Aarhus University Hospital over a period of 34 years.

MATERIALS AND METHODS

All patients who fulfilled the criteria for RIS and were treated for RIS in the period 1979-2013 were included. Patient data were retrieved from the Aarhus Sarcoma Registry and the National Danish Sarcoma Database, crosschecked with the National Register of Pathology and validated using the patients' medical records. The primary end point was the effect of surgery and treatment intent on overall survival. Overall survival is reported using the Kaplan-Meier estimates and compared using the Log-rank test. Descriptive statistics are presented for patients, tumours and treatment characteristics.

RESULTS

Of 2845 patients diagnosed with sarcoma between 1979 and 2013, 64 (2%) were diagnosed with RIS. The median interval from the original malignancy was 11 years. The most common histological type was undifferentiated pleomorphic sarcoma (33%). Curative treatment was intended for 45 patients. Fifty patients underwent surgery, of whom 80% had microscopically radical resection (R0). The 5-year overall survival for the whole cohort was 32%. Patients who underwent surgery had a significantly better overall survival compared with patients who were not treated with surgery. In the univariate Cox proportional hazard analyses, no metastases at diagnosis, surgery and R0 resection were favourable prognostics factors of survival.

CONCLUSION

This study showed that RIS patients are unique in their epidemiology and tumour characteristics. They have a poor prognosis and need special research investigating new intensive treatment strategies to improve the outcome.

Secondary Intracranial Tumors Following Radiotherapy for Pituitary Adenomas: A Systematic Review

Pituitary adenomas are often treated with radiotherapy for the management of tumor progression or recurrence. Despite the improvement in cure rates, patients treated by radiotherapy are at risk of development of secondary malignancies. We conducted a comprehensive literature review of the secondary intracranial tumors that occurred following radiotherapy to pituitary adenomas to obtain clinicopathological characteristics. The analysis included 48 neuroepithelial tumors, 37 meningiomas, and 52 sarcomas which were published between 1959–2017, although data is missing regarding overall survival and type of irradiation in a significant proportion of the reports. The average onset age for the pituitary adenoma was 37.2 ± 14.4 years and the average latency period before the diagnosis of the secondary tumor was 15.2 ± 8.7 years. Radiotherapy was administered in pituitary adenomas at an average dose of 52.0 ± 19.5 Gy. The distribution of pituitary adenomas according to their function was prolactinoma in 10 (7.2%) cases, acromegaly in 37 (27.0%) cases, Cushing disease in 4 (2.9%) cases, PRL+GH in 1 (0.7%) case, non-functioning adenoma in 57 (41.6%) cases. Irradiation technique delivered was lateral opposing field in 23 (16.7%) cases, 3 or 4 field technique in 27 (19.6%) cases, rotation technique in 10 (7.2%) cases, radio surgery in 6 (4.3%) cases. Most of the glioma or sarcoma had been generated after lateral opposing field or 3/4 field technique. Fibrosarcomas were predominant before 1979 (p < 0.0001). The median overall survival time for all neuroepithelial tumors was 11 months (95% confidence intervals (CI), 3–14). Patients with gliomas treated with radiotherapy exhibited a non-significant positive trend with longer overall survival. The median overall survival time for sarcoma cases was 6 months (95% CI, 1.5–9). The median survival time in patients with radiation and/or chemotherapy for sarcomas exhibited a non-significant positive trend with longer overall survival. In patients treated with radiotherapy for pituitary adenomas, the risk of secondary tumor incidence warrants a longer follow up period. Moreover, radiation and/or chemotherapy should be considered in cases of secondary glioma or sarcoma following radiotherapy to the pituitary adenomas.

Genome-wide analysis of abdominal and pleural malignant mesothelioma with DNA arrays reveals both common and distinct regions of copy number alteration

Malignant mesothelioma (MM) is an aggressive tumor arising from mesothelial linings of the serosal cavities. Pleural space is the most common site, accounting for about 80% of cases, while peritoneum makes up the majority of the remaining 20%. While histologically similar, tumors from these sites are epidemiologically and clinically distinct and their attribution to asbestos exposure differs. We compared DNA array-based findings from 48 epithelioid peritoneal MMs and 41 epithelioid pleural MMs to identify similarities and differences in copy number alterations (CNAs). Losses in 3p (BAP1 gene), 9p (CDKN2A) and 22q (NF2) were seen in tumors from both tumor sites, although CDKN2A and NF2 losses were seen at a higher rate in pleural disease (p<0.01). Overall, regions of copy number gain were more common in peritoneal MM, whereas losses were more common in pleural MM, with regions of loss containing known tumor suppressor genes and regions of gain encompassing genes encoding receptor tyrosine kinase pathway members. Cases with known asbestos causation (n = 32 ) were compared with those linked to radiation exposure (n = 9 ). Deletions in 6q, 14q, 17p and 22q, and gain of 17q were seen in asbestos-associated but not radiation-related cases. As reported in post-radiation sarcoma, gains outnumbered losses in radiation-associated MM. The patterns of genomic imbalances suggest overlapping and distinct molecular pathways in MM of the pleura and peritoneum, and that differences in causation (i.e., asbestos vs. radiation) may account for some of these site-dependent differences.

The novel myxofibrosarcoma cell line MUG-Myx1 expresses a tumourigenic stem-like cell population with high aldehyde dehydrogenase 1 activity

BACKGROUND

Myxofibrosarcoma comprises a spectrum of malignant neoplasms withprominent myxoid stromata, cellular pleomorphism, and distinct curvilinear vascular patterns. These neoplasms mainly affect patients in the sixth to eighth decades of life and the overall 5-year survival rate is 60-70%.

METHODS

After the establishment of the novel myxofibrosarcoma cell lines MUG-Myx1, cells were characterized using short tandem repeat (STR), copy number variation (CNV), and genotype/loss-of-heterozygosity (LOH) analyses. The growth behaviour of the cells was analyzed with the xCELLigence system and an MTS assay. The tumourigenicity of MUG-Myx1 was proved in NOD/SCID mice. Additionally, a stem-like cell population with high enzymatic activity of aldehyde dehydrogenase 1 (ALDH1(high)) was isolated for the first time from myxofibrosarcoma cells using the Aldefluor® assay followed by FACS analysis.

RESULTS

The frozen primary parental tumour tissue and the MUG-Myx1 cell line showed the same STR profile at the markers D3S1358, TH01, D21S11, D18S51, Penta E, D5S818, D13S317, D7S820, D16S539, CSF1PO, Penta D, Amelogenin, D8S1179, TPOX, and FGY. Typically, myxofibrosarcoma gain and/or amplification was mapped to 7p21.3-q31.1, q31.1-q31.33, q33-q36.2, p21.3, p21.2, p14.1-q11.23, q31.33-q33, p21.2-p14.1, q11.23-q21.3, q36.2-q36.3, which, respectively are known to harbour tumour-associated genes, including TIF, BRAF, MLL3, SMO, and MET. Typically an LOH for myxofibrosarcoma on chr5 q21 was found. In addition, MUG-Myx1 ALDH1(high) cells showed an upregulation of the ABC transporter ABCB1 and ABCG2; higher c-Myc, E-cadherin and SOX-2 expression; and a higher potential for tumourigenicity and proliferation levels.

CONCLUSION

The new myxofibrosarcoma cell line MUG-Myx1 was established to enrich the bank of publicly available cell lines, with respect to providing comprehensive genetic and epigenetic characterization. Furthermore, because of their tumourigenicity, the cell line is also suitable for in vivo experiments.

High frequency of MYC gene amplification is a common feature of radiation-induced sarcomas. Further results from EORTC STBSG TL 01/01

Irradiation is a major causative factor among the small subgroup of sarcomas with a known etiology. The prognosis of radiation-induced sarcomas (RIS) is significantly worse than that of their spontaneous counterparts. The most frequent histological subtypes include undifferentiated pleomorphic sarcomas, angiosarcomas, and leiomyosarcomas. A high frequency of MYC amplifications in radiation-induced angiosarcomas, but not in primary angiosarcomas, has recently been described. To investigate whether MYC amplifications are also frequent in RIS other than angiosarcomas, we analyzed the MYC amplification status of 83 RIS and 192 sporadic sarcomas by fluorescence in situ hybridization. We found significantly higher numbers of MYC amplifications in RIS than in sporadic sarcomas (P < 0.0001), especially in angiosarcomas, undifferentiated pleomorphic sarcomas, and leiomyosarcomas. Angiosarcomas were special in that MYC amplifications were particularly frequent and always high level, while other RIS showed low-level amplifications. We conclude that MYC amplifications are a frequent feature of RIS as a group and may contribute to the biology of these tumors.

Radiation-induced sarcoma of the breast: a systematic review

INTRODUCTION

Radiation-induced sarcoma (RIS) is a rare, aggressive malignancy. Breast cancer survivors treated with radiotherapy constitute a large fraction of RIS patients. To evaluate evidenced-based practices for RIS treatment, we performed a systematic review of the published English-language literature.

METHODS

We performed a systematic keyword search of PubMed for original research articles pertaining to RIS of the breast. We classified and evaluated the articles based on hierarchical levels of scientific evidence.

RESULTS

We identified 124 original articles available for analysis, which included 1,831 patients. No randomized controlled trials involving RIS patients were found. We present the best available evidence for the etiology, comparative biology to primary sarcoma, prognostic factors, and treatment options for RIS of the breast.

CONCLUSION

Although the evidence to guide clinical practice is limited to single institutional cohort studies, registry studies, case-control studies, and case reports, we applied the available evidence to address clinically relevant questions related to best practice in patient management. Surgery with widely negative margins remains the primary treatment of RIS. Unfortunately, the role of adjuvant and neoadjuvant chemotherapy remains uncertain. This systematic review highlights the need for additional well-designed studies to inform the management of RIS.

Not all sarcomas developed in irradiated tissue are necessarily radiation-induced--spectrum of disease and treatment characteristics

BACKGROUND

Sarcomas in irradiated tissue (SITs) are often considered with second cancers, although they usually present distinct dose-response, genetic and clinical patterns. The contribution of radiation in SIT development is likely, but remains unproven in many cases.

MATERIALS AND METHODS

We reviewed the literature for published data on SITs.

RESULTS

SITs incidence ranged between 0.03% and 0.2%. Median latency was 15 years. Angiosarcoma was the second most common subtype after undifferentiated sarcomas of malignant fibrous histiocytoma (MFH). C-Myc overexpression can be used to identify radiation-induced angiosarcoma, and a recently described transcriptomic signature of genes involved in chronic oxidative stress and mitochondrial dysfunction may indicate radiation causality. Osteosarcomas were often associated with genetic predisposition. Five-year survival rates rarely exceeded 30% because the therapeutic possibilities were often limited by the first cancer. Chemotherapy response may differ from that of de novo sarcomas.

CONCLUSION

SITs present different characteristics from non-sarcomatoid second cancers. Reporting of SIT cases and the establishment of tissue and serum banks is necessary to better understand and validate the recently discovered radiation signature.

Prognostic implication of MET overexpression in myxofibrosarcomas: an integrative array comparative genomic hybridization, real-time quantitative PCR, immunoblotting, and immunohistochemical analysis

It remains obscure in myxofibrosarcoma about the basis of tumorigenesis, progression, and metastasis. Chromosome 7 gains are common in some sarcomas, including myxofibrosarcoma, whereas the specific oncogenes are yet to be characterized. We performed an integrative study of MET gene at 7q31.2 to elucidate its implication in myxofibrosarcoma. Focused on candidate oncogenes on chromosome 7, 385K array comparative genomic hybridization was used to profile DNA copy number alterations of 12 samples. MET transcript was successfully quantified by real-time RT-PCR for 16 laser-microdissected tumors and two myxofibrosarcoma cell lines (NMFH-1, OH931). MET immunoexpression was assessable in 86 primary localized tumors with follow-up. To analyze endogenous MET expression and activation, NMFH-1 and OH931 cells, both with wild-type MET gene, were subjected to Western blotting and hepatocyte growth factor-treated NMFH-1 cells were evaluated for the kinetics of MET tyrosine phosphorylation. Non-random large-scale gains on 7q were detected in five cases, delineating three recurrent amplicons, 7q21.11-7q21.3, 7q22.1-22.3, and 7q31.1-7q32.3, in which the locus of MET displayed increased copy number, among others. MET mRNA was upregulated in OH931, NMFH-1, and nine tumors (56%), whereas neither gene dosage nor mRNA expression of MET was associated with clinicopathological factors. In contrast, MET protein overexpression, present in 67% of cases, was highly related to deep location (P=0.004), higher grades (P=0.001), and more advanced stages (P<0.001). Importantly, MET overexpression independently portended inferior metastasis-free survival (P=0.004) and overall survival (P=0.0221). Expressing activating phospho-MET at Tyr(1234)/Tyr(1235), OH931 cells had more abundant total MET than NMFH-1 cells, whereas the latter became promptly phosphorylated on stimulation of hepatocyte growth factor. In primary myxofibrosarcomas, MET overexpression, as a frequent event, is likely driven by 7q gains with mRNA upregulation, associated with important prognosticators, and independently predictive of worse outcomes, highlighting its possible causative function in tumor aggressiveness and potentiality as a therapeutic target.

Cytogenetic and molecular characterization of plutonium-induced rat osteosarcomas

The association between ionizing radiation and the subsequent development of osteosarcoma has been well described, but little is known about the cytogenetic and molecular events, which could be involved in the formation of radiation-induced osteosarcomas. Here, we performed comparative genomic hybridization (CGH) to detect chromosomal copy number changes in a series of 16 rat osteosarcomas induced by injection of plutonium-238. Recurrent gains/amplifications were observed at chromosomal regions 3p12-q12, 3q41-qter, 4q41-qter, 6q12-q16, 7q22-q34, 8q11-q23, 9q11-q22, 10q32.1-qter, and 12q, whereas recurrent losses were observed at 1p, 1q, 3q23-q35, 5q21-q33, 8q24-q31, 10q22-q25, 15p, 15q, and 18q. The gained region at 7q22-q34 was homologous to human chromosome bands 12q13-q15/8q24/22q11-q13, including the loci of Mdm2, Cdk4, c-Myc and Pdgf-b genes. The lost regions at 5q21-q33, 10q22-q25 and 15q contained tumor suppressor genes such as p16INK4a/p19ARF, Tp53 and Rb1. To identify potential target gene(s) for the chromosomal aberrations, we compared the expression levels of several candidate genes, located within the regions of frequent chromosomal aberrations, between the tumors and normal osteoblasts by using quantitative RT-PCR analysis. The Cdk4, c-Myc, Pdgf-b and p57KIP2 genes were thought to be possible target genes for the frequent chromosomal gain at 7q22-34 and loss at 1q in the tumors, respectively. In addition, mutations of the Tp53 gene were found in 27% (4 of 15) osteosarcomas. Our data may contribute to further understanding of the molecular mechanisms underlying osteosarcomas induced by ionizing radiation in human.

MYC high level gene amplification is a distinctive feature of angiosarcomas after irradiation or chronic lymphedema

Angiosarcomas (AS) are rare vascular malignancies that arise either de novo as primary tumors or secondary to irradiation or chronic lymphedema. The cytogenetics of angiosarcomas are poorly characterized. We applied array-comparative genomic hybridization as a screening method to identify recurrent alterations in 22 cases. Recurrent genetic alterations were identified only in secondary but not in primary AS. The most frequent recurrent alterations were high level amplifications on chromosome 8q24.21 (50%), followed by 10p12.33 (33%) and 5q35.3 (11%). Fluorescence in situ hybridization analysis in 28 primary and 33 secondary angiosarcomas (31 tumors secondary to irradiation, 2 tumors secondary to chronic lymphedema) confirmed high level amplification of MYC on chromosome 8q24.21 as a recurrent genetic alteration found exclusively in 55% of AS secondary to irradiation or chronic lymphedema, but not in primary AS. Amplification of MYC did not predispose to high grade morphology or increased cell turnover. In conclusion, despite their identical morphology, secondary AS are genetically different from primary AS and are characterized by a high frequency of high level amplifications of MYC. This finding may have implications both for the diagnosis and treatment of these tumors.

Examining racial disparities in colorectal cancer care

African Americans are disproportionately burdened with colorectal cancer. Although incidence and mortality rates have declined in the past two decades, the disparity in health outcomes has progressively increased. This comprehensive review examines the existing literature regarding racial disparities in colorectal cancer screening, stage at diagnosis, and treatment to determine if differences exist in the quality of care delivered to African Americans. A comprehensive review of relevant literature was performed. Two databases (EBSCOHOST Academic Search Premier and Scopus) were searched from 2000 to 2007. Articles that assessed racial disparities in colorectal cancer screening, stage of disease at diagnosis, and treatment were selected. The majority of studies identified examined colorectal cancer screening outcomes. Although racial disparities in screening have diminished in recent years, African American men and women continue to have higher colorectal cancer incidence and mortality rates and are diagnosed at more advanced stages. Several studies regarding stage of disease at diagnosis identified socioeconomic status (SES) and health insurance status as major determinants of disparity. However, some studies found significant racial disparities even after controlling for these factors. Racial disparities in treatment were also found at various diagnostic stages. Many factors affecting disparities between African Americans and Whites in colorectal cancer incidence and mortality remain unexplained. Although the importance of tumor biology, genetics, and lifestyle risk factors have been established, prime sociodemographic factors need further examination to understand variances in the care of African Americans diagnosed with colorectal cancer.

Application of immunohistochemistry to soft tissue neoplasms

CONTEXT

Soft tissue tumors are composed of numerous and complex diagnostic entities. Because of this complexity and the recognition of an intermediate malignancy category including some tumors with a deceptively bland histologic appearance, soft tissue tumors may represent a major diagnostic challenge to the general practicing pathologist.

OBJECTIVE

To correctly diagnose soft tissue tumors with the ancillary use of immunohistochemistry.

DATA SOURCES

Review of the current literature with emphasis on those tumors for which immunohistochemistry has proven to be particularly useful.

CONCLUSIONS

Immunohistochemistry plays an important role in the diagnosis of soft tissue tumors. One of its major utilities is to correctly identify a tumor as being of mesenchymal or nonmesenchymal origin. Once mesenchymal origin has been established, histologic subtyping according to specific cell lineage may be achieved with the use of lineage-specific markers. Tumors of uncertain cell lineage and tumors with primitive small round cell morphology are often characterized by a unique immunohistochemical phenotype. In this group of tumors, immunohistochemistry is most widely applied and is of greatest value. Despite the rapid development of molecular genetic techniques, immunohistochemistry still remains the most important diagnostic tool in the diagnosis of soft tissue tumors aside from recognition of morphologic features and clinical correlation.

Sarcomas and sarcomatoid tumor after radiotherapy of oral squamous cell carcinoma: analysis of 4 cases

Radiation-induced sarcoma (RIS) or postirradiation sarcoma has been reported rarely as a long-term complication of radiation therapy (RT). We report 4 cases of oral sarcomas or sarcomatoid tumors with a rather short latency period after radiotherapy of the prior OSCC. Histopathological evaluation and immunohistochemical study were performed using a panel of markers including vimentin, cytokeratin, S-100, desmin, myoglobin, HHF-35, p53, and p16. All reported cases were positive for vimentin and negative for cytokeratin. Two cases were positive for myoglobin, desmin, or HHF-35, and were probably myogenic origin. One case was possibly a fibrosarcoma and the subclassification of the other one was not specified. Diverse expression of p53 and p16 was further observed in these 4 cases. Report of the complicated clinical processes and the analysis of genetic markers of these cases provide useful clinical and pathogenetic insights of mesenchymal malignancies associated with a status post OSCC radiation.

Radiation-induced rhabdomyosarcomatous transformation of a recurrent meningeal haemangiopericytoma

A 53-year-old woman presented in 1979 with a posterior fossa meningeal haemangiopericytoma (HPC) for which she underwent surgical resection and post-operative radiotherapy. Repeated tumour recurrences occurred 18 years afterwards which were treated with resections and stereotactic radiotherapy. Surgery for tumour recurrence in 2005 revealed features of rhabdomyosarcomatous transformation. To our knowledge, this is the first reported case of rhabdomyosarcomatous transformation within a HPC which was likely to be radiation-induced, and was associated with relentless disease progression more than 20 years after the initial presentation.

Radiation-induced sarcomas after radiotherapy for breast carcinoma

BACKGROUND

Sarcomas are a rare complication of radiotherapy for breast carcinoma and patients have a poor prognosis. The incidence, histology, and management of patients with sarcomas were reviewed in the current study.

METHODS

The authors reviewed the records of 16,705 patients with breast carcinoma. Of these, 13,472 (81%) were treated with megavoltage radiotherapy and 3233 were treated without at the Institute Curie (Paris, France) between 1981 and 1997. Median doses of 50-55 grays (Gy) in 25-27 fractions were delivered to the whole breast over a period of 5-5.5 weeks (2 Gy/day, 5 weekly fractions) followed, when indicated, by a 16-26-Gy boost to the tumor or tumor bed. Treatment of radiation-induced sarcomas (RIS) consisted mostly of radical surgery and chemotherapy.

RESULTS

Overall, 35 patients developed sarcomas. Of these, 27 fulfilled the Cahan criteria. The median follow-up was 9.3 years (range, 1-22.4 years). The latency period ranged from 3 years to 20.3 years. Thirteen sarcomas were located in the breast, 5- in the chest wall, 3 in the sternum, 2 in the supraclavicle, 1 in the scapula, and 3 in the axilla. Histologic evaluation identified 13 angiosarcomas, 3 osteosarcomas, 5 undifferentiated sarcomas, 1 malignant fibrous histiocytoma, 2 leiomyosarcomas, 1 fibrosarcoma, 1 rhabdomyosarcoma, and 1 myosarcoma. The cumulative RIS incidence was 0.07% (+/- 0.02) at 5 years, 0.27% (+/- 0.05) at 10 years, and 0.48% (+/- 0.11) at 15 years. Standardized incidence ratios were 10.2 (95% confidence interval, 9.03-11.59) for irradiated patients and 1.3 (0.3-3.6) for nonirradiated patients. Of the 27 patients, 15 died of sarcoma within 1 month to 14.5 years (mean, 34.2 +/- 0.7 months). The 5-year actuarial survival rate after diagnosis of RIS was 36% (+/- 0.11).

CONCLUSIONS

The current study confirmed the rarity of RIS. However, it showed that the risk increased with time. Therefore, careful, long-term follow-up of patients treated with radiotherapy is needed for early detection and efficacious treatment of these malignancies.

Radio-induced malignancies of the scalp about 98 patients with 150 lesions and literature review

INTRODUCTION

- The induction of malignant diseases is one of the most concerning late effects of ionizing radiation. The topic of this study deals with skin tumors developed in the irradiated areas in children given X-ray therapy for tinea capitis.

MATERIAL AND METHODS

- All patients with malignant tumors of the scalp referred to Salah Azaiz Institute between 1970 and 2001 have been questioned in order to determine if there had been a prior X-ray irradiation for tinea capitis, its modality, and its consequences. The first scalp irradiation goes back to 1922 and the last was performed in 1963.

RESULTS

- Ninety-eight patients with 150 radio-induced cancers of the scalp following irradiation for tinea capitis are reported (1.5 lesion per patient). The patients were irradiated in various hospitals and dispensaries throughout the country. Eighty-one patients (82%) had only one session of radiation. The average age at irradiation was 12 (+/-6) years, the latent period for radiation-induced skin cancers was 36 (+/-14) years. In 61 patients (62%), the scalp appeared normal and in 38% radiodermatitis was noted. Patient age at diagnosis of malignancy varied from 20 to 83 years with an average of 47 years. Basal cell carcinomas (125 cases) and spinocellular carcinomas (16 cases) were the most common, three other cases of annexial tumors, two malignant non-Hodgkin's lymphomas and four melanoma lesions are also present. Radiotherapy was used for the treatment of 74 patients (alone in 42 and associated with surgery in 32 patients); 14 patients had exclusive surgical excision.

CONCLUSIONS

- Basal cell carcinomas are the most frequent tumors arising on chronic radiodermatitis. In spite of the long latency period, patients' young age at irradiation explained the occurrence of these cancers at a relatively young age. Literature review is suggesting recessive mutation of tumor-suppressor genes as the characteristic abnormality in radio-induced cancer.

Second cancers after radiotherapy: any evidence for radiation-induced genomic instability?

Do second primary cancers in humans arise from radiation-induced somatic genomic instability after radiotherapy for the first malignancy? The amount of truly pertinent human information on this issue is sparse, leading to the conclusion that we cannot confirm or refute that instability induction by radiation is involved. However, the in vitro findings of radiation-induced genomic instability through bystander effects or increased mutation rates in cell progeny of apparently normal but irradiated cells are provocative and their transferability to human in vivo biology deserves further investigation. We describe possible animal and human studies to stimulate ideas, but the collaborative commitment of multiple large institutions to tumor tissue procurement and retrieval will be essential. In addition, detecting the temporal progression of genomic instability and identifying the salient genetic events as being radiation-induced will be pivotal. Execution of some of the studies suggested is not possible now, but applying next-generation methods could bring the concepts to fruition. As nearly one in 10 cancer diagnoses are second (or higher) malignancies, it is important to understand the contribution of radiotherapy to second cancer induction and pursue well-coordinated efforts to determine the role of induced genomic instability.

High-resolution mapping of amplifications and deletions in pediatric osteosarcoma by use of CGH analysis of cDNA microarrays

Conventional cytogenetic and comparative genomic hybridization (CGH) studies have shown that osteosarcomas (OSs) are characterized by complex structural and numerical chromosomal alterations and gene amplification. In this study, we used high-resolution CGH to investigate recurrent patterns of genomic imbalance by use of DNA derived from nine OS tumors hybridized to a 19,200-clone cDNA microarray. In six OSs, there was copy number gain or amplification of 6p, with a minimal region of gain centering on segment 6p12.1. In seven OSs, the pattern of amplification affecting chromosome arm 8q showed high-level gains of 8q12-21.3 and 8q22-q23, with amplification of the MYC oncogene at 8q24.2. Seven OSs showed copy number gain or amplification of 17p between the loci bounded by GAS7 and PMI (17p11.2-17p12), and three of these tumors also showed small losses at 17p13, including the region containing TP53. An in silico analysis of the distribution of segmental duplications (duplicons) in this region identified a large number of tracts consisting of paralogous sequences mapping to the 17p region, encompassing the region of deletions and amplifications in OS. Interestingly, within this same region there were clusters of duplicons and several genes that are expressed during bone morphogenesis and in OS. In summary, microarray CGH analysis of the chromosomal imbalances of OS confirm the overall pattern observed by use of metaphase CGH and provides a more precise refinement of the boundaries of genomic gains and losses that characterize this tumor.