Tumor samples from a retrospective series of 209 patients with HGSOC (Study groups 1, 2 and 3 from 2 independent cohorts; Supplementary Tables 1, 2 and Supplementary Fig. 1) who did not receive neoadjuvant chemotherapy were analyzed for early TLS (eTLS) and mature TLS (mTLS) using immunofluorescence microscopy based on CD4, CD8, CD20, CD21, CD23, DC-LAMP and GZMB (Fig. 1A, Supplementary Fig. 2A-C). Here, CD4 is linked to neoplasm.