Precise clinical staging by diagnostic imaging is essential for determination of initial treatment for gastric cancer. Indeed, cT3 and T4 diseases with lymph node metastasis (T3-4/N+) were candidate of neoadjuvant chemotherapy (NAC) followed by gastrectomy, defined as cStageIII in 8th edition of AJCC/UICC TNM classification. However, pathological T3-4/N+ diseases could contain some cases that were underestimated as cStage I/II and excluded from target of NAC. This study aims to examine the accuracy of preoperative diagnosis and the prognosis from each cStage in pathological T3-4/N+ gastric cancers.
The study analyzed gastric cancer patients who received gastrectomy and diagnosed as pathological T3-4/N+ deseases between Jun 2000 and Jun 2012 at Kanagawa Cancer Center. The clinical and pathological data were analyzed retrospectively. Patients who received preoperative chemotherapy were excluded. The proportion of each cStage was investigated based on the 8th edition of AJCC/UICC, and 5-year overall survival rate (5yOS) for each cStage was calculated using the Kaplan-Meier method.
In total, 337 patients were diagnosed as pathological T3-4/N+ diseases and included in this study. In clinical staging, 48 patients (14.2%) were diagnosed as cStageI, 10 patients (3.0%) as cStageIIA, 109 patients (32.3%) as cStageIIB, 159 patients (47.2%) as cStageIII, 6 patients (1.8%) as cStageIVA, and 5 patients (1.5%) as cStageIVB. 5yOS stratified by cStage was 77.0% in cStageI, 90.0% in cStageIIA, 52.2% in cStageIIB, 49.0% in cStageIII, and 0% in cStageIVA/IVB. Furthermore, survival curve of cStageIIB and cStageIII were approximately overlapped.
Among pathological T3-4/N+ diseases, the underestimation as cStageI and cStageIIA was acceptable, because of relative low frequency and good prognosis without NAC. Meanwhile, the underestimation as cStageIIB could not be ignored, because patients diagnosed as cStageIIB occupied one third of pathological T3-4/N+ disease and had poor prognosis comparable to cStageIII. We need to consider underestimation of preoperative diagnosis, when we determine target of NAC for advanced gastric cancer.
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