The genomic complexity of profound copy number aberrations has prevented effective molecular stratification of ovarian cancers. Here, to decode this complexity, we derived copy number signatures from shallow whole-genome sequencing of 117 high-grade serous ovarian cancer (HGSOC) cases, which were validated on 527 independent cases. We show that HGSOC comprises a continuum of genomes shaped by multiple mutational processes that result in known patterns of genomic aberration. Copy number signature exposures at diagnosis predict both overall survival and the probability of platinum-resistant relapse. Measurement of signature exposures provides a rational framework to choose combination treatments that target multiple mutational processes.

We have profiled, for the first time, an evolving human metastatic microenvironment, measuring gene expression, matrisome proteomics, cytokine and chemokine levels, cellularity, ECM organization and biomechanical properties, all on the same sample. Using biopsies of high-grade serous ovarian cancer (HGSOC) metastases that ranged from minimal to extensive disease, we show how non-malignant cell densities and cytokine networks evolve with disease progression. Multivariate integration of the different components allowed us to define for the first time, gene and protein profiles that predict extent of disease and tissue stiffness, whilst also revealing the complexity and dynamic nature of matrisome remodeling during development of metastases. Although we studied a single metastatic site from one human malignancy, a pattern of expression of 22 matrisome genes distinguished patients with a shorter overall survival in ovarian and twelve other primary solid cancers, suggesting that there may be a common matrix response to human cancer.

The CRS system is reproducible and shows prognostic significance for high-grade serous carcinoma. Implementation in international pathology reporting has been proposed by the International Collaboration on Cancer Reporting, and the system could potentially have an impact on patient care and research.