PIK3CA and ovarian clear cell cancer: Clear cell ovarian cancer comprises 5% to 10% of post‐menopausal EOC17; women present young and there is a higher incidence in those of Asian origin and an association with hypercalcaemia.19 Women diagnosed at early stage have an excellent prognosis, but response rates and survival in advanced disease are poor.17, 20 The most common genetic pathogenic variants are in ARID1A, PIK3CA, PTEN, CTNNB1 and PP2R1A genes,6 with ARID1A variants occurring in approximately 50% and PIK3CA variants in approximately 36% of clear cell cases.9