Due to lacking of evidence on surveillance for gastric cancer (GC), this study aimed to determine the optimal postsurgical surveillance strategy for stage II/III GC patients and compare its cost-effectiveness with traditional surveillance strategies.

Background The development of existing follow-up strategies is mainly based on experts' consensus and researches on recurrence patterns due to the lack of direct evidence and unified standards. On the one hand, it is unreasonable to carry out the same postsurgical surveillance for all stage II/III GC patients. Additionally, In addition to the early detection of recurrence, the optimal follow-up strategy should also balance cost and effectiveness. There were no criteria for the arrangement of follow-up in different guidelines, and the optimal postoperative follow-up strategy for patients with stage II/III GC remains unclear.

Methods Prospectively collected data from stage II/III GC patients (n=1,661) who underwent gastrectomy at Fujian Medical University Union Hospital (FJMUUH) between January 2010 and October 2015. For external validation, two independent cohorts were included, which were composed of 380 stage II/III GC patients who underwent gastrectomy at the Mayo Clinic between July 1991 and July 2012 and 270 stage II/III GC patients at the Qinghai university affiliated hospital (QUAH) between May 2010 and Oct 2014. Random survival forest models were used to predict dynamic recurrence hazards and to construct individual surveillance strategies for stage II/III GC. Cost-effectiveness were assessed by Markov model.

Inclusion Criteria:

• (1) Eastern Cooperative Oncology Group (ECOG) scores of 0 (asymptomatic) or 1 (symptomatic but completely ambulatory); (2) pathologically confirmed AGC (pStage II and III, except pT4b); (3) no distant metastasis or invasion of adjacent organs (e.g., pancreas, spleen, liver, and colon) detected intra- or post-operatively; and (4) D2 lymph node dissection of gastric cancer.

Exclusion Criteria:

• (1) American Society of Anesthesiologists (ASA) grade >2; (2) remnant gastric or neuroendocrine cancer; (3) history of neoadjuvant chemotherapy; (4) palliative surgery; and (5) death within 30 days after surgery.

A total of 1,661 stage II/III GC patients who underwent gastrectomy at Fujian Medical University Union Hospital (FJMUUH) between January 2010 and October 2015. For external validation, two independent cohorts were included, which were composed of 380 stage II/III GC patients who underwent gastrectomy at the Mayo Clinic between July 1991 and July 2012 and 270 stage II/III GC patients at the Qinghai university affiliated hospital (QUAH) between May 2010 and Oct 2014.