Abstract 1417P
Background
The indication for postoperative adjuvant chemotherapy for advanced gastric cancer is determined based on the pathological diagnosis. However, several investigators have reported that serosal invasion diagnosed macroscopically during surgery is superior to pathological diagnosis for the prediction of peritoneal recurrence. In order to seek more sensitive predictive factors for peritoneal recurrence, predictability of peritoneal recurrence and survival by serosal invasion diagnosed macroscopically during surgery (sT) and diagnosed pathologically (pT) were investigated.
Methods
A total of 501 patients underwent R0 resection in JCOG0110 study was included in this study. Tumor depth of M, SM, MP, SS were defined as serosal invasion negative (T-), and SE, SI were defined as serosal invasion positive (T+). The risk of peritoneal recurrence in sT and in pT was evaluated with death and other type of recurrence as competing risks using the Fine & Gray model. For relapse-free survival (RFS), Cox regression analysis was performed separately incorporating sT or pT as covariates.
Results
sT+ and pT+ was observed in 225 patients (44.9%) and in 132 patients (26.3%), respectively. Regarding the concordance between sT and pT, sT+/pT+ was observed in 108 patients (21.6%), sT+/pT- in 117 patients (23.4%), sT-/pT+ in 24 patients (4.8%), and sT-/pT- in 252 patients (50.3%), respectively. Both sT and pT were selected as independent risk of peritoneal recurrence, with the hazard ratio of 5.04 (95% CI, 2.15-11.83) in sT and 5.09 (2.30-11.30) in pT by multivariable analysis. Multivariable analysis showed both sT and pT were independent factors for RFS with hazard ratio of 2.09 (1.52-2.87) in sT and 2.14 (1.54-2.99) in pT. The 5-year RFS according to the subgroup was 50.0% in sT+/pT+, 63.2% in sT+/pT-, 62.5% in sT-/pT +, and 81.7% in sT-/pT-. Survival in sT+/pT- was almost identical to that in sT-/pT+.
Conclusions
Macroscopic serosal invasion diagnosed at the time of surgery showed a similar predictive value for peritoneal recurrence as pathologically diagnosed serosal invasion. Establishment of novel staging system incorporating macroscopic serosal invasion is warranted.
Clinical trial identification
NCT00112099.
Editorial acknowledgement
Legal entity responsible for the study
Japan Clinical Oncology Group.
Funding
The Ministry of Health, Labor and Welfare, Japan and National Cancer Center, Japan.
Disclosure
All authors have declared no conflicts of interest.