In fact, as already mentioned, whole exome sequencing studies have revealed that many of the PIK3CA mutations found in the normal uterine and endometriotic epithelium are non-silent and often coincide with cancerogenic mutations [30] (Figure 1), while at the same time, the most frequent gene alterations in ovarian clear cell carcinoma (OCCC) affect the KRAS/PI3K pathway (82%) [55]. Here, PIK3CA is linked to ovarian clear cell cancer.