BACKGROUND: Endometrial cancer (EC) is one of the most common gynecologic malignancy, mostly in postmenopausal women. The gold standard treatment for EC is surgery, but in the early stages, it is possible to opt for conservative treatment. In the last decade, different clinical and pathological markers have been studied to identify women who respond to conservative treatment. A lot of immunohistochemical markers have been evaluated to predict response to progestin treatment, even if their usefulness is still unclear; the prognosis of this neoplasm depends on tumor stage, and a specific therapeutic protocol is set according to the stage of the disease. OBJECTIVE: (1) To provide an overview of the conservative management of Stage 1A Grade (G) 2 endometrioid EC (FIGO) and the oncological and reproductive outcomes related; (2) to describe the molecular alterations before and after progestin therapy in patients undergoing conservative treatment. MATERIALS AND METHODS: A systematic computerized search of the literature was performed in the main electronic databases (MEDLINE, Embase, Web of Science, PubMed, and Cochrane Library), from 2010 to September 2021, in order to evaluate the oncological and reproductive outcomes in patients with G2 stage IA EC who ask for fertility-sparing treatment. The expression of several immunohistochemical markers was evaluated in pretreatment phase and during the follow-up in relation to response to hormonal therapy. Only scientific publications in English were included. The risk of bias assessment was performed. Review authors' judgments were categorized as "low risk," "high risk," or "unclear risk" of bias. RESULTS: Twelve articles were included in the study: 7 observational studies and 5 case series/reports. Eighty-four patients who took progestins (megestrol acetate, medroxyprogesterone acetate, and/or levonorgestrel-releasing intrauterine devices) were analyzed. The publication bias analysis turned out to be "low." 54/84 patients had a complete response, 23/84 patients underwent radical surgery, and 20/84 had a relapse after conservative treatment. Twenty-two patients had a pregnancy. The length of follow-up was variable, from 6 to 142 months according to the different studies analyzed. Several clinical and pathological markers have been studied to identify women who do not respond to conservative treatment: PR and ER were the most studied predictive markers, in particular PR appeared as the most promising; MMR, SPAG9, Ki67, and Nrf2-survivin pathway provided good results with a significant association with a good response to progestin therapy. However, no reliable predictive markers are currently available to be used in clinical practice. CONCLUSIONS: The conservative treatment may be an option for patients with stage IA G2 EEC who desire to preserve their fertility. The immunohistochemical markers evaluation looks promising in predicting response to conservative treatment. Further large series and randomized clinical trials are needed to confirm these results.