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.

Neoadjuvant chemotherapy for radiation-associated soft-tissue sarcoma: A case report

Radiation-associated sarcomas are rare and aggressive types of sarcomas that can occur after exposure to ionizing radiation. We examine a case of radiation-associated undifferentiated/unclassified soft-tissue sarcoma with primary disease in the chest wall. The optimal treatment of these patients is surgical resection if possible; however, the role of chemotherapy has not been well defined. The patient described herein had a central tumor in the chest wall. Since many of these patients have borderline resectable tumors, the use of neoadjuvant chemotherapy may be helpful to downstage the tumors for possible surgical resection. In this case, doxorubicin plus ifosfamide chemotherapy was employed with a favorable therapeutic effect prior to being resected. To our knowledge this is the first report of greater than 90% necrosis in a patient with radiation-associated undifferentiated/unclassified soft-tissue sarcoma treated with chemotherapy for a borderline resectable mass.

Mutational landscape of radiation-associated angiosarcoma of the breast

Purpose

Radiation-associated breast angiosarcomas are a rare complication of radiation therapy for breast carcinoma. With relatively little is known about the genetic abnormalities present in these secondary tumors, we examined genomic variation in biospecimens from radiation-associated breast angiosarcomas.

Experimental Design

Patients were identified that had a previous breast cancer diagnosis, received radiation therapy, and developed angiosarcoma in the ipsilateral breast as the earlier cancer. Tumor regions were isolated from archival blocks using subsequent laser capture microdissection. Next generation sequencing was performed using a targeted panel of 160 cancer-related genes. Genomic variants were identified for mutation and trinucleotide-based mutational signature analysis.

Results

44 variants in 34 genes were found in more than two thirds of the cases; this included 12 variants identified as potentially deleterious. Of particular note, the BRCA1 DNA damage response pathway was highly enriched with genetic variation. In a comparison to local recurrences, 14 variants in 11 genes were present in both the primary and recurrent lesions including variants in genes associated with the DNA damage response machinery. Furthermore, the mutational signature analysis shows that a previously defined IR signature is present in almost all of the current samples characterized by predominantly C→T substitutions.

Conclusions

While radiation-associated breast angiosarcomas are relatively uncommon, their prognosis is very poor. These data demonstrate a mutational pattern associated with genes involved in DNA repair. While important in revealing the biology behind these tumors, it may also suggest new treatment strategies that will prove successful.

Expression of miRNA-26b-5p and its target TRPS1 is associated with radiation exposure in post-Chernobyl breast cancer

Ionizing radiation is a well-recognized risk factor for the development of breast cancer. However, it is unknown whether radiation-specific molecular oncogenic mechanisms exist. We investigated post-Chernobyl breast cancers from radiation-exposed female clean-up workers and nonexposed controls for molecular changes. Radiation-associated alterations identified in the discovery cohort (n = 38) were subsequently validated in a second cohort (n = 39). Increased expression of hsa-miR-26b-5p was associated with radiation exposure in both of the cohorts. Moreover, downregulation of the TRPS1 protein, which is a transcriptional target of hsa-miR-26b-5p, was associated with radiation exposure. As TRPS1 overexpression is common in sporadic breast cancer, its observed downregulation in radiation-associated breast cancer warrants clarification of the specific functional role of TRPS1 in the radiation context. For this purpose, the impact of TRPS1 on the transcriptome was characterized in two radiation-transformed breast cell culture models after siRNA-knockdown. Deregulated genes upon TRPS1 knockdown were associated with DNA-repair, cell cycle, mitosis, cell migration, angiogenesis and EMT pathways. Furthermore, we identified the interaction partners of TRPS1 from the transcriptomic correlation networks derived from gene expression data on radiation-transformed breast cell culture models and sporadic breast cancer tissues provided by the TCGA database. The genes correlating with TRPS1 in the radiation-transformed breast cell lines were primarily linked to DNA damage response and chromosome segregation, while the transcriptional interaction partners in the sporadic breast cancers were mostly associated with apoptosis. Thus, upregulation of hsa-miR-26b-5p and downregulation of TRPS1 in radiation-associated breast cancer tissue samples suggests these molecules representing radiation markers in breast cancer.

Radiation-associated colon cancer: A case report

Radiation-associated colon cancer is a rare clinical entity. We herein describe the case of a patient with radiation-associated colon cancer who had undergone low anterior resection for rectal cancer following preoperative radiotherapy. Certain characteristics of radiation-associated colon cancer are highlighted. The patient was a 48-year-old man who had undergone low anterior resection for rectal cancer following preoperative radiotherapy at a total dose of 50 Gy, at the age of 29 years. When the patient presented at the University of Tokyo Hospital, 19 years after the surgery, he complained of severe anal pain and frequent defecation. Colonoscopy revealed two flat tumors in the sigmoid colon, located 10 cm to the oral side of the anastomosis site, which were diagnosed as well-differentiated adenocarcinomas. In addition, colonoscopy identified five flat polyps near the tumors, which were resected endoscopically. Computed tomography and magnetic resonance imaging revealed a mass in the sigmoid colon and no evidence of distant metastasis. Laparoscopic-assisted intersphincteric resection of the rectum and sigmoid colon with diverting ileostomy was performed. There were no specific postoperative complications and the patient was discharged from the hospital on the 20th postoperative day. On pathological examination, the resected rectum and sigmoid colon contained two separate tumors and six flat polyps. The two tumors were diagnosed as well-differentiated adenocarcinomas with invasion of the subserosa and submucosa, respectively. A total of 17 regional lymph nodes without metastasis were resected. The six flat polyps were diagnosed as tubular adenomas. We herein present a case of a radiation-associated colon cancer in a patient who had undergone low anterior resection for rectal cancer following preoperative radiotherapy 19 years prior. Colonoscopic surveillance of radiation-associated colon cancer may be indicated for rectal cancer patients treated with preoperative radiotherapy, particularly for those with long-standing radiation-induced colitis.

MYC immunohistochemistry in angiosarcoma and atypical vascular lesions: practical considerations based on a single institutional experience

Angiosarcoma (AS) is an uncommon vascular malignancy with an aggressive clinical course. Radiation-associated angiosarcoma (RAAS) and Stewart-Treves syndrome are associated with MYC gene amplification and protein overexpression, while other radiation-associated vascular lesions including atypical vascular lesions (AVL) are not associated with MYC overexpression. In contrast, de novo AS represent a group of molecularly heterogeneous tumours, for which MYC expression has not been extensively examined. In this study, MYC immunohistochemistry (IHC) was performed on representative whole tissue sections of a large retrospective cohort of de novo AS, RAAS, Stewart-Treves syndrome, and AVL and evaluated using a semi-quantitative scoring method. MYC is strongly expressed in the majority of RAAS and Stewart-Treves syndrome. De novo AS demonstrate variable MYC expression, with high-grade tumours showing significantly higher MYC expression than low-grade tumours. In contrast, MYC expression in AVL is predominantly negative but may occasionally show focal staining. These results indicate that unequivocal strong MYC IHC staining supports the diagnosis of RAAS. In rare cases of RAAS without strong MYC expression, however, particularly relatively low-grade tumours for which the differential diagnosis includes AVL, the distinction between these lesions should be made on morphological grounds using previously established criteria (i.e., significant atypia, deep invasion, infiltrative growth, etc.). Increased MYC expression in high-grade de novo AS suggests that MYC overexpression may play a role in the pathogenesis of these tumours, and MYC IHC may be a prognostic and/or therapeutic biomarker in a subset of these tumours.

MRI findings of radiation-associated angiosarcoma of the breast (RAS)

PURPOSE

To describe the magnetic resonance imaging (MRI) characteristics of radiation-associated breast angiosarcomas (RAS).

MATERIALS AND METHODS

In this Institutional Review board (IRB)-approved retrospective study, 57 women were diagnosed with pathologically confirmed RAS during the study period (January 1999 to May 2013). Seventeen women underwent pretreatment breast MRI (prior to surgical resection or chemotherapy), of which 16 studies were available for review. Imaging features, including all available mammograms, ultrasounds, and breast MRIs, of these patients were evaluated by two radiologists independently and correlated with clinical management and outcomes.

RESULTS

The median age of patients at original breast cancer diagnosis was 69.3 years (range 42-84 years), with average time from initial radiation therapy to diagnosis of RAS of 7.3 years (range 5.1-9.5 years). Nine women had mammograms (9/16, 56%) and six had breast ultrasound (US) (6/16, 38%) prior to MRI, which demonstrated nonsuspicious findings in 5/9 mammograms and 3/6 ultrasounds. Four patients had distinct intraparenchymal masses on mammogram and MRI. MRI findings included diffuse T2 high signal skin thickening (16/16, 100%). Nearly half (7/16, 44%) of patients had T2 low signal intensity lesions; all lesions rapidly enhanced on postcontrast T1 -weighted imaging. All women underwent surgical resection, with 8/16 (50%) receiving neoadjuvant chemotherapy. Four women died during the study period.

CONCLUSION

Clinical, mammographic, and sonographic findings of RAS are nonspecific and may be occult on conventional breast imaging; MRI findings of RAS include rapidly enhancing dermal and intraparenchymal lesions, some of which are low signal on T2 weighted imaging.