Elsevier

Surgery

Volume 158, Issue 6, December 2015, Pages 1573-1580
Surgery

Stomach/Intestine
Postoperative adjuvant chemotherapy with S-1 alters recurrence patterns and prognostic factors among patients with stage II/III gastric cancer: A propensity score matching analysis

https://doi.org/10.1016/j.surg.2015.05.017Get rights and content

Background

A phase 3 evidence indicates that S-1 adjuvant is beneficial among East Asian patients with stage II/III gastric cancer (GC). However, little is known about the changes in prognostic factors and recurrence patterns after it has become widespread as a standard of care. The present study compared prognostic factors of patients with stage II/III GC treated with or without S-1 adjuvant with formulate appropriate risk stratification strategies.

Methods

We enrolled 171 patients with stage II/III GC, 92 patients who underwent gastrectomy alone, and 79 patients treated with S-1 adjuvant. To balance more strictly the essential variables including stage of progression, we conducted propensity score analysis and 70 pairs of patients were generated from each group. Prognostic factors were compared between the groups and initial recurrence patterns were investigated to explore reasons for the change.

Results

In concordance with the previous phase 3 trial, overall and recurrence-free survival were better for the S-1 adjuvant group. In the surgery alone group, carcinoembryonic antigen ≥5 ng/mL, total gastrectomy, vessel invasion, pT4, and stage 3 were identified as significant prognostic factors. In striking contrast, macroscopic tumor size ≥50 mm was the only significant prognostic factor for the S-1 adjuvant group. The lower overall recurrence rate of the S-1 adjuvant group was attributable mainly to a significant decrease of peritoneal recurrence.

Conclusion

Prognostic factors changed substantially after implementation of S-1 adjuvant treatment. Macroscopic tumor size should be considered for patient stratification and selection of treatment options for patients with stage II/III GC.

Section snippets

Criteria for patient selection and propensity score matching

We reviewed the medical records of our prospectively collected database of 1,078 patients who underwent gastrectomy for GC at the Department of Gastroenterological Surgery, Nagoya University between January 1999 and July 2014. Patients were selected if they met the eligibility criteria as follows: pathologically confirmed adenocarcinoma of the stomach, histologically confirmed R0 gastric resection (D2) with negative resection margins, pathologic evaluation of the number of resected lymph nodes

Patient characteristics of patients before and after propensity score matching

Patients categorized either as surgery alone or S-1 adjuvant were matched one-to-one by the use of propensity score matching and 70 pairs of patients were generated, and the resulting score-matched pairs were used in subsequent analyses. Fifteen patients were categorized in the surgery alone group after standardization of S-1 adjuvant in Japan (2007) because of patient refusal including an economic reason. Demographics and preoperative clinical characteristics of unmatched and matched

Discussion

The prognosis of patients with GC depends primarily on their stage. The prognosis of patients with Stage I GC, in which the tumor is limited to pT1 or pT2N0, is excellent with low risk for recurrences,16 and adjuvant therapy is not indicated for this population. In contrast, patients with Stage IV GC almost invariably suffer from dismal prognosis and should undergo systemic chemo- or chemoradiation therapy, palliative surgery, or best supportive care with curative resection reserved for

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