If looks could kill: morphologic subtypes of high-grade serous ovarian cancer

Abstract

<h3>Objectives:</h3> Despite similar histologic appearance amongst high-grade serous ovarian cancers (HGSOC), anecdotally there are differences in gross appearance. However, no systematic framework to classify morphologic differences exists. Therefore, we aimed to determine whether high-grade serous ovarian cancers (HGSOC) can be reliably divided into distinct gross morphologic subtypes and to assess clinical outcomes and molecular features of these subtypes. <h3>Methods:</h3> A retrospective review was performed of video-recordings from patients who underwent laparoscopic assessment of disease burden prior to primary debulking surgery (PDS) or neoadjuvant chemotherapy (NACT). Video recordings were reviewed by at least 2 physicians. A total of 4 sites (diaphragm, omentum, peritoneum, and pelvis) were assessed and classified as type I (deep, infiltrative disease with distortion of surrounding tissue) or type II (superficial, exophytic disease bordered by normal tissue). Tumor tissues from 16 of these chemotherapy-naïve patients were analyzed by multi-platform omics (RNA sequencing, proteomics). Clinical outcomes were assessed utilizing a prospectively collected database and compared by morphology using t-test or Fisher's exact test. <h3>Results:</h3> Of the 99 evaluable patients, 60 exhibited uniform morphology at all involved metastatic sites (65% type I and 35% type II), and 81 exhibited a predominating morphology (58% type I and 42% type II). A total of 164 images were reviewed by a third physician with 83.5% inter-rater concordance (κ=0.6446). Patients with uniform type 1 (n=34)tumor morphology were more likely to exhibit an excellent response to NACT (defined as radiologic or CA-125 complete response) than those with type II (n=16) tumor morphology (47% vs 18%, p=0.13). Patients with type II predominant tumor morphology had a significantly higher estimated blood loss at the time of interval debulking surgery (p=0.008) as well as longer operative time (p=0.03) compared with type I tumor morphology. Patients with complete type II morphology were more likely to have a modified Fagotti score of <8 (p=0.026), and thus were more likely to be triaged to PDS. On histopathologic review of 7 type I cases and 4 type II cases, no obvious histo-pathological pattern dominated either type. We identified distinct molecular differences between the 2 types, including increased TGF-β expression in type I and increased MYC expression in type II. Type I tumors seem to have abundant stroma and are immunologically active, whereas type II tumors seem to be dominated by cancer cells, have little stroma, and are immunologically cold. <h3>Conclusions:</h3> There are at least two distinct gross morphological patterns of HGSOC with unique molecular differences and responses to chemotherapy. These findings could have major clinical implications for tailored therapeutic strategies.