Not All STICs Are Equal: Unraveling the Implications of Precursor Heterogeneity.

Serous tubal intraepithelial carcinomas (STIC) are precursors of high-grade serous carcinoma (HGSC), the deadliest subtype of ovarian carcinoma. To establish clinically actionable strategies against these lesions, a better understanding of the mutational, transcriptional, and genetic/epigenetic alterations, as well as interactions among epithelial, immune, and stromal cells, is essential. In this issue of Cancer Research, Shih and colleagues conducted the first integrated spatial multiomics analysis of ovarian precancerous lesions, revealing substantial heterogeneity within the fallopian tube epithelium that may influence cancer susceptibility. They described four molecular subclasses of STICs according to their epithelial transcriptomic profiles: proliferative, immunoreactive, mixed, and dormant (PIMD) subtypes. Molecular links of this "PIMD" STIC subclassification to tumor progression were proposed, uncovering early events in ovarian tumorigenesis and potential genetic drivers of STIC heterogeneity. Furthermore, the STIC subtypes showed distinct histologic and molecular characteristics that warrant further investigation to develop a deeper understanding of the molecular and cellular processes driving the evolution of STIC heterogeneity, which may facilitate the development of early diagnostic approaches for HGSC. Collectively, the findings that not all STICs are equal open new avenues for further clinicopathologic, translational, and basic research to improve risk classification and early intervention in HGSC. See related article by Chang et al., p. 1739.