Abstract
BackgroundPrevious studies have shown that the all-cause mortality and non-colorectal cancer mortality of patients with fecal occult blood test (FOBT) positivity are significantly increased, implying that FOBT results may have more prognostic value.MethodsRetrospective analysis was performed for gastric cancer (GC) patients who underwent R0 gastrectomy from July 2007 to July 2014 at our hospital. Propensity score matching (PSM) was used to reduce confounding bias and a computerized technique for the nearest available score matching without replacement was applied. The cumulative survival rate was calculated using the Kaplan-Meier method and a log-rank test. Cox proportional hazards regression and logistic regression was used to determine the independent prognostic factors associated with survival and postoperative complications, respectively. The expression level of tumor-associated macrophages (TAMs) and proinflammatory cytokines (TNF-α, IL-6) were evaluated by immunohistochemical (IHC).ResultsA total of 3,003 patients were included and 246 patients (8.2%) were in preoperative FOBT positive status. There was no significant difference in demographic data between preoperative FOBT positive and negative group after a 1:4 PSM. The overall postoperative complications, major complications, and anastomotic leakage were significantly higher in the preoperative FOBT-positive group than in the preoperative FOBT-negative group. Moreover, preoperative FOBT-positivity was an independent risk factor for 5-year overall survival (OS) (HR: 1.32, p = 0.005). For stage II/III patients, the postoperative adjuvant chemotherapy (PAC) benefit was found in preoperative FOBT-negative group (5-year OS: 49.9 vs. 36.8%, p = 0.001), whereas the PAC benefit was lost in preoperative FOBT-positive groups (5-year OS: 40.8 vs. 37.7% p = 0.896). Finally, IHC found that preoperative FOBT-positivity in patients was significantly associated with higher TAMs infiltration and higher expression of IL-6 and TNF-α in tumor tissues than in the preoperative FOBT-negative group.ConclusionAs a simple and low-cost method, preoperative FOBT results can predict both complications and survival after R0 gastrectomy for GC. More importantly, stage II/III GC patients with FOBT-positive seem not benefit from PAC alone. Further exploration is warranted.
Highlights
In the past few decades, despite significant advances in early diagnosis, radical surgery, and chemotherapy, gastric cancer (GC) remains the fifth-most common malignancy in the world and ranks third in tumor-related mortality [1]
Paraffin-embedded sections of fecal occult blood test (FOBT)-negative and FOBTpositive patients (60 cases each) were randomly selected from the propensity score-matched patients (n = 1,230) for IHC analysis to explore the association between FOBT status and the tumor immune microenvironment (CD68, IL-6, and tumor necrosis factor-a (TNF-a) expression)
In a study of individuals in the Netherlands undergoing screening for colorectal cancer by FOBT, it was found that fewer than 1% of patients with a positive result from the FOBT to receive a diagnosis of gastric cancers within 3 years [22]
Summary
In the past few decades, despite significant advances in early diagnosis, radical surgery, and chemotherapy, gastric cancer (GC) remains the fifth-most common malignancy in the world and ranks third in tumor-related mortality [1]. Radical gastrectomy is the dominant treatment for patients with resectable gastric cancer. It has been found that some prognostic scores based on the tumor immune microenvironment (TIM) or gene expression predicted the PAC response in stage II/III GC patients [2,3,4,5,6,7]. They have not been routinely used in clinical practice due to their complicated operation and high cost. Previous studies have shown that the all-cause mortality and noncolorectal cancer mortality of patients with fecal occult blood test (FOBT) positivity are significantly increased, implying that FOBT results may have more prognostic value
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