Introduction/Background High Grade Serous Carcinoma (HGSC) of the female genital tract can be divided into Four molecular subtypes (C1, C2, C4 and C5) by RNA sequencing. In addition to distinct expression profiles, the molecular subtypes also display distinct clinical features. To date, there is also no published data that relates to molecular subtype and tumour macroscopic appearance at the time of primary surgery as described by the surgical team

Aims-

1. To explore the possible correlation between the macroscopic appearance of HGSC at the time of primary surgery and molecular subtype.

2. Evaluate pre-surgical MRI scans to determine if there are subtype-specific characteristics that can be observed.

3. To validate the histopathologic classification criteria of molecular subtyping for HGSC.

Methodology Prospective, exploratory pilot study of patients undergoing primary surgery for HGSC. Pre-operative MRI was assessed for PCI scores and lesions characterisations by a dedicated radiologist. Intra-operatively- cases underwent surgical assessment including PCI & Fagotti scores, lesions characterisation and operative findings. Tumour samples were collected and sent to molecular subtyping using the RNA-seq platform, as well as Histopathological assessment to predict the molecular subtype, by a dedicated blinded pathologist.

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Abstract #824 Figure 1

Results Eighteen cases of HGSC were included in this study, with 48 samples. All molecular subtypes were represented in our patient population. Intra-operative photos show distinct features of the different subtypes (to be presented at the talk).

Conclusion This pilot study suggests that different molecular subtypes of HGSC have different lesion appearance and disease spread, and potentially be predicted by the surgeon to guide clinical management.