PTEN loss appears in pre-invasive lesions in the fallopian tube and therefore is a putative early driver in HGSOC.25 Our results show that loss of PTEN expression was similar across all stages of HGSOC (with the exception of moderately lower prevalence of PTEN negativity in stage II), consistent with previous evidence that PTEN is commonly lost early in tumour progression (Fig. 2a). The gene discussed is PTEN; the disease is neoplasm.