Extending adjuvant S-1 chemotherapy beyond 6 months after resection of pancreatic ductal adenocarcinoma (PDAC) does not improve outcomes, according to research published in Cancer

Researchers found no significant difference in recurrence-free survival (RFS) or overall survival (OS) between patients who received S-1 for 6 months and patients who received S-1 for more than 7 months.

The researchers analyzed real-world data from 3949 PDAC patients in Japan who underwent resection and received adjuvant S-1 chemotherapy. 

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Patients were grouped by duration of therapy. The standard-duration group received S-1 for 180 days ± 30 days (n=1653). The longer-duration group received S-1 for more than 210 days (n=975). 

The researchers compared RFS and OS between these groups but excluded patients who had a recurrence within 210 days of the start of adjuvant chemotherapy.

There were no significant differences in outcomes between the groups. The 5-year RFS rate was 37.8% for the standard-duration group and 36.2% for the longer-duration group (P =.6186). The 5-year OS rates were 52.8% and 53.4%, respectively (P =.5850). 

A multivariable analysis and a propensity score matching analysis confirmed that a longer duration of S-1 adjuvant chemotherapy did not improve RFS or OS. 

The researchers noted that these results will need further confirmation in prospective studies, but the findings should “help clinicians determine whether to extend S-1 adjuvant chemotherapy in patients who have completed a 6-month course.” 

Disclosures: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.


Tomimaru Y, Eguchi H, Inoue Y, et al. Impact of S-1 adjuvant chemotherapy longer than 6 months on survival in patients with resected pancreatic cancer: A nationwide survey by the Japan Pancreas Society based on real-world data. Cancer. Published online December 12, 2022. doi:10.1002/cncr.34580