Poor prognostic and staging value of tumor deposit in locally advanced rectal cancer with neoadjuvant chemoradiotherapy

Tumor deposit (TD) was associated with poor survival in colorectal cancer. However, its prognostic and staging value in locally advanced rectal cancer (LARC) patients following neoadjuvant chemoradiotherapy (neo-CRT) is controversial. Four hundred and ninety-five LARC patients following neo-CRT and surgery were retrospectively analyzed. Univariate and multivariate analyses were performed using Kaplan-Meier method and Cox proportional hazards regression in all lymph node (LN) -negative and LN-positive patients. Next, we used three methods to classify the counts of LNs and TDs (oN, only LN counts; n1N, counts according to the N1c standards; n2N, total counts of LNs and TDs) to evaluate the impact of TD on N staging. TD-positive patients were associated with more aggressive clinicopathological features. In multivariate analyses, TD was an independent poor prognostic factor of overall survival (OS), disease-free survival (DFS), and local recurrence-free survival in all patients. In LN-negative patients, TD was an independent poor prognostic factor of OS, DFS and distant metastasis-free survival (DMFS). In LN-positive patients, TD has poor prognostic value only in patients with one positive LN. Three multivariate analyses according to three N staging methods showed that oN was not an independent prognostic factor, whereas n1N and n2N were independently associated with poor survival in OS, DFS and DMFS. The n2N method seemed to be better than n1N method. TD is an independent poor prognostic factor in LARC patients following neo-CRT, especially in patients with no more than one positive LN. TD probably should be considered as one positive LN when performing N staging.