The role of local excision in rectal cancer after complete response to neoadjuvant treatment

Correlation between pathological response of primary tumour and mesorectal lymph node\r\ninvolvement was prospectively evaluated to assess the role of local excision (LE) in rectal\r\ncancer after complete response to neoadjuvant treatment. A series of 272 consecutive\r\nrectal cancer, submitted to neoadjuvant radiochemotherapy (RCT) and surgery with total\r\nmesorectal excision (TME) were analysed. Tumour downstaging (pT) and tumour regression\r\ngrade (TRG) together with sex, age, location of the tumour, pre-treatment clinical stage,\r\ntype of chemoradiation and operation performed entered in an univariate and multivariate\r\nanalysis.\r\nPathological complete response on primary tumour was found in 56 patients (20.6%).\r\nLymph node metastases were found in 72 patients (26.5%). The rate of positive nodes was\r\n1.8% for pT0 and TRG1 cases, respectively, to go up to 6.3% for pT1 and 24.1% for TRG 2\r\ncases, respectively. At the univariate analysis, factors with a statistically significant\r\ncorrelation with the risk of lymph node metastasis were: clinical pre-treatment N stage\r\n(p<0.05), pT stage (p<0.001) and TRG (p<0.001). At the multivariate analysis, the best\r\npredictors of pathologic lymph node involvement were pT stage (p = 0.0013 ) and TRG\r\n(p = 0.0011). Because LE is an adequate technique to assess the tumour pathological\r\nresponse and nodal involvement in pT0 or TRG1 cases seems extremely infrequent, radical\r\nresection is probably not justified after pathological complete response. Prospective\r\nrandomized trials are necessary to establish if, in these cases, LE can guarantee the same\r\noncologic results offered by the currently adopted protocols of RCT followed by radical\r\nresections.