Analysis of Risk Factors for Lymph Nodal Involvement in Early Stages of Rectal Cancer: When Can Local Excision Be Considered an Appropriate Treatment? Systematic Review andMeta-Analysis of the Literature

Background. Over the past ten years oncological outcomes achieved by local excision techniques (LETs) as the sole treatment for early stages of rectal cancer (ESRC) have been often disappointing. The reasons for these poor results lie mostly in the high risk of the disease's diffusion to local-regional lymph nodes even in ESRC. Aims. This study aims to find the correct indications for LET in ESRC taking into consideration clinical-pathological features of tumours thatmay reduce the risk of lymph node metastasis to zero. Methods. Systematic literature review and meta-analysis of casistics of ESRC treated with total mesorectal excision with the aim of identifying risk factors for nodal involvement. Results. The risk of lymph node metastasis is higher in G >= 2 and T >= 2 tumours with lymphatic and/or vascular invasion. Other features which have not yet been sufficiently investigated include female gender, TSM stage > 1, presence of tumour budding and/or perineural invasion. Conclusions. Results comparable to radical surgery can be achieved by LET only in patients with T-1 N-0 G(1) tumours with low-risk histological features, whereas deeper or more aggressive tumours should be addressed by radical surgery (RS).