DEEP MOLECULAR TRACKING OVER THE 12-YEAR DEVELOPMENT OF ENDOMETRIAL CANCER FROM HYPERPLASIA IN A SINGLE PATIENT

Although the progressive histologic steps leading to endometrial cancer (EndoCA), the most common female reproductive tract malignancy, from endometrial hyperplasia are well-established, the molecular changes accompanying this malignant transformation in a single patient have never been described. We had the unique opportunity to investigate the paired histologic and molecular features associated with the 12-yr development of EndoCA in a postmenopausal female who could not undergo hysterectomy and instead underwent progesterone treatment. Using a specially designed 58-gene next-generation sequencing panel, we analyzed a total of 10 sequential biopsy samples collected over this time frame. A total of eight pathogenic/likely pathogenic mutations in seven genes,APC,ARID1A,CTNNB1,CDKN2A,KRAS,PTEN, andTP53, were identified. APTENnonsense mutation p.W111* was present in all samples analyzed except histologically normal endometrium. Apart from thisPTENmutation, the only other recurrent mutation wasKRASG12D, which was present in six biopsy samplings, including histologically normal tissue obtained at the patient's first visit but not detectable in the cancer. ThePTENp.W111* mutant allele fractions were lowest in benign, inactive endometrial glands (0.7%), highest in adenocarcinoma (36.9%), and, notably, were always markedly reduced following progesterone treatment. To our knowledge, this report provides the first molecular characterization of EndoCA development in a single patient. A singlePTENmutation was present throughout the 12 years of cancer development. Importantly, and with potential significance toward medical and nonsurgical management of EndoCA, progesterone treatments were consistently noted to markedly decreasePTENmutant allele fractions to precancerous levels.