Background/Aims: Immune checkpoint blockade has recently been reported to be effective in treating microsatellite instability (MSI)-high tumors. Therefore, sufficient sampling of histological specimens is necessary in cases of unresectable pancreatic cancer (UR-PC). This multicenter study investigated the efficacy of endoscopic ultrasound-guided fine-needle biopsy (EUS-FNB) using a Franseen needle for MSI evaluation in patients with UR-PC. Methods: A total of 89 patients with UR-PC who underwent endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) or EUS-FNB using 22-G needles at three hospitals in Japan (2018–2021) were enrolled. Fifty-six of these patients (FNB 23 and FNA 33) were followed up or evaluated for MSI. Patient characteristics, UR-PC data, and procedural outcomes were compared between patients who underwent EUS-FNB and those who underwent EUS-FNA. Results: No significant difference in terms of sufficient tissue acquisition for histology was observed between patients who underwent EUS-FNB and those who underwent EUS-FNA. MSI evaluation was possible significantly more with tissue samples obtained using EUS-FNB than with tissue samples obtained using EUS-FNA (82.6% [19/23] vs. 45.5% [15/33], respectively; p<0.01). In the multivariate analysis, EUS-FNB was the only significant factor influencing the possibility of MSI evaluation. Conclusions EUS-FNB using a Franseen needle is desirable for ensuring sufficient tissue acquisition for MSI evaluation.

The patient was a 68-year-old woman who was diagnosed with stage IIIA cervical cancer and pyometra. Concurrent chemoradiotherapy was planned. She was admitted to our hospital 3 weeks after the initial examination due to vaginal bleeding and worsening of lower abdominal pain. On hospital day 5, she developed a fever, and free gas in the peritoneal cavity and ascites were confirmed by contrast-enhanced computed tomography. Emergency surgery was performed for suspected generalized peritonitis attributed to perforation in the digestive tract or uterus. A large amount of purulent ascites and 2 perforations in the anterior wall of the uterus, but none in the digestive tract, were observed. Peritoneal lavage and drainage were performed, and a colostomy was created. The patient was managed in the intensive care unit until postoperative day 13 due to septic shock and acute renal failure. After the peritonitis resolved, radiation therapy alone was provided, and then chemotherapy was started to treat residual lesions. Pyometra recurred, and transvaginal drainage was performed to prevent perforation of the uterus. However, a few days later, a colouterine fistula and an enterocutaneous fistula developed simultaneously, and her general condition worsened. In advanced cervical cancer complicated by pyometra, various complications can develop that are difficult to manage (e.g., uterine perforation and fistula formation due to radiation enteritis and dermatitis). 　This case demonstrates the importance of uterine drainage at appropriate timing, which can contribute to improved prognosis.