The Genomic Landscape of Early-Stage Ovarian High-Grade Serous Carcinoma

• Published in: Clinical cancer research Vol. 28; no. 13; pp. 2911 - 2922
• Main Authors: Cheng, Zhao, Mirza, Hasan, Ennis, Darren P, Smith, Philip, Morrill Gavarró, Lena, Sokota, Chishimba, Giannone, Gaia, Goranova, Theodora, Bradley, Thomas, Piskorz, Anna, Lockley, Michelle, Kaur, Baljeet, Singh, Naveena, Tookman, Laura A, Krell, Jonathan, McDermott, Jacqueline, Macintyre, Geoffrey, Markowetz, Florian, Brenton, James D, McNeish, Iain A
• Format: Journal Article
• Language: English
• Published: United States 01.07.2022
• Subjects: Carcinoma, Ovarian Epithelial; Female; Genomics; High-Throughput Nucleotide Sequencing; Humans; Middle Aged; Mutation; Ovarian Neoplasms - genetics; Ovarian Neoplasms - pathology
• ISSN: 1078-0432; 1557-3265
• DOI: 10.1158/1078-0432.CCR-21-1643

Ovarian high-grade serous carcinoma (HGSC) is usually diagnosed at late stage. We investigated whether late-stage HGSC has unique genomic characteristics consistent with acquisition of evolutionary advantage compared with early-stage tumors. We performed targeted next-generation sequencing and shallow whole-genome sequencing (sWGS) on pretreatment samples from 43 patients with FIGO stage I-IIA HGSC to investigate somatic mutations and copy-number (CN) alterations (SCNA). We compared results to pretreatment samples from 52 patients with stage IIIC/IV HGSC from the BriTROC-1 study. Age of diagnosis did not differ between early-stage and late-stage patients (median 61.3 years vs. 62.3 years, respectively). TP53 mutations were near-universal in both cohorts (89% early-stage, 100% late-stage), and there were no significant differences in the rates of other somatic mutations, including BRCA1 and BRCA2. We also did not observe cohort-specific focal SCNA that could explain biological behavior. However, ploidy was higher in late-stage (median, 3.0) than early-stage (median, 1.9) samples. CN signature exposures were significantly different between cohorts, with greater relative signature 3 exposure in early-stage and greater signature 4 in late-stage. Unsupervised clustering based on CN signatures identified three clusters that were prognostic. Early-stage and late-stage HGSCs have highly similar patterns of mutation and focal SCNA. However, CN signature analysis showed that late-stage disease has distinct signature exposures consistent with whole-genome duplication. Further analyses will be required to ascertain whether these differences reflect genuine biological differences between early-stage and late-stage or simply time-related markers of evolutionary fitness. See related commentary by Yang et al., p. 2730.