Study design and sample
We conducted a retrospective analysis including a total of 313 patients with GTN who were diagnosed and treated at the Hospital of Obstetrics and Gynecology, Fudan University in Shanghai, China from January 2014 to December 2017. Placental site trophoblastic tumor (PSTT) and extrauterine epithelioid trophoblastic tumors (ETT) are insensitive to chemotherapy and usually require adjuvant surgery14; these have distinct biological behaviors with typical GTN15. Twelve patients with pathologically confirmed PSTT and three with ETT were excluded, leaving 298 GTN patients for analyses, including 233 (78.2%, 233/298) low-risk GTN (FIGO score ≤6) and 47 (15.8%, 47/298) high-risk GTN (FIGO score 7–11), and 18 (6.0%, 18/298) ultra-high-risk GTN (FIGO >12, as well as patients with liver, brain, or extensive metastases) (Figure 1). The clinical characteristics, treatment details, outcomes, and prognoses of these 298 patients with GTN were retrieved from the medical records in our hospital. Ethical approval was obtained from the Ethics Committee of Hospital of Obstetrics and Gynecology, Fudan University, Shanghai, China.