Aim: In this population-based study, the aim was to investigate risk factors for lymph node metastases and to construct a risk stratification index with relevance for pre-operative planning in T1 and T2 rectal cancers.
Methods: Data were retrieved from The Swedish Rectal Cancer Register, a mandatory, national, prospectively collected data base. All T1 and T2 rectal cancers treated with abdominal resection surgery without neo-adjuvant or adjuvant radio-chemotherapy from 2007 to 2010 were analysed. T-stage, sm-level, histologic differentiation, mucinous tumour type, blood vessel- and perineural infiltration, tumour location (in cm from the anal verge), age and gender were evaluated as potential predictors of lymph node metastases, using uni- and multivariate logistic regression.
Results: T2-stage (odds ratio [OR]=2.0), poor differentiation (OR=6.5) and vascular infiltration (OR=4.3) were identified as significant risk-factors for lymph node metastases in the multivariate analysis. The risk stratification index shows the risk for lymph node metastases gradually increasing from 6% to 65% and 11% to 78% in T1 and T2 cancers respectively, when adding the risk factors one by one.
Conclusion: There is a considerable span in the risk for lymph node metastases between low risk T1 and high risk T2 rectal cancer. Using the risk stratification-model, with the concept of local excision as a macro-biopsy with standby for subsequent immediate radical resection surgery in high-risk cases, could benefit patients by providing the advantages of local excision yet ensuring adequate oncologic outcome.
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