Tumor-stroma ratio as prognostic factor for survival in rectal adenocarcinoma: A retrospective cohort study

AIM To evaluate the prognostic value of the tumor-stroma ratio(TSR) in rectal cancer.METHODS TSR was determined on hematoxylin and eosin stained histological sections of 154 patients treated for rectal adenocarcinoma without prior neoadjuvant treatment in the period 1996-2006 by two observers to assessreproducibility. Patients were categorized into three categories: TSR-high [carcinoma percentage(CP) ≥ 70%], TSR-intermediate(CP 40%, 50% and 60%) and TSR-low(CP ≤ 30%). The relation between categorized TSR and survival was analyzed using Cox proportional hazards model.RESULTS Thirty-six(23.4%) patients were scored as TSR-low, 70(45.4%) as TSR-intermediate and 48(31.2%) as TSRhigh. TSR had a good interobserver agreement(κ = 0.724, concordance 82.5%). Overall survival(OS) and disease free survival(DFS) were significantly better for patients with a high TSR(P = 0.01 and P = 0.02, respectively). A similar association existed for disease specific survival(P = 0.06). In multivariate analysis, patients without lymph node metastasis and an intermediate TSR had a higher risk of dying from rectal cancer(HR = 5.27, 95%CI: 1.54-18.10), compared to lymph node metastasis negative patients with a high TSR. This group also had a worse DFS(HR = 6.41, 95%CI: 1.84-22.28). An identical association was seen for OS. These relations were not seen in lymph node metastasis positive patients. CONCLUSION The TSR has potential as a prognostic factor for survival in surgically treated rectal cancer patients, especially in lymph node negative cases.