Chemoresistance of Gastric-Type Mucinous Carcinoma of the Uterine Cervix: A Study of the Sankai Gynecology Study Group

Objective Gastric-type mucinous carcinoma (GAS) is a novel variant of mucinous carcinoma of the uterine cervix, characterized by aggressive clinical behavior and absence of high-risk human papillomavirus. We conducted this study to evaluate the chemosensitivity of GAS compared with that of usual-type endocervical adenocarcinoma (UEA) in patients who had been enrolled in our previous study. Methods Of 52 patients from our previous phase 2 study (SGSG005) of neoadjuvant chemotherapy with docetaxel and carboplatin for stage IB2 to IIB nonsquamous cervical cancer, 47 (stage IB2, 12; stage IIA2, 7; stage IIB, 28) were enrolled in this study with written informed consent. The biopsy specimens before neoadjuvant chemotherapy and surgical specimens after chemotherapy were centrally reviewed based on the updated World Health Organization classification (2014). Results Of 47 patients with nonsquamous cell carcinoma, 20 (42.6%) were diagnosed with UEA, 13 (27.7%) with GAS, 12 (25.5%) with adenosquamous carcinoma, and 1 patient each (2%) with small cell carcinoma and serous carcinoma. Consequently, 33 patients, consisting of 20 patients with UEA and 13 patients with GAS, were eligible for the current study. The response rate of GAS was significantly lower than that of UEA (46.2% vs 85.0%, P = 0.048). Of 16 cases of stage II UEA, 11 (68.8%) were downstaged on microscopic examination of postsurgical specimens, but none of the 8 patients with stage II GAS showed any response (P < 0.01). Two inoperative tumors were GAS. With a median follow-up duration of 56 months, the 5-year progression-free and overall survival rates of GAS were significantly worse than those of UEA (38.5% vs 75.0% [P = 0.011] and 36.9% vs 90.0% [P < 0.001], respectively). Conclusions These findings suggest that GAS should be distinguished from UEA by its chemoresistance, necessitating an alternative treatment strategy established for this distinct subtype of endocervical adenocarcinoma.