Value of transrectal ultrasonography for tumor node metastasis restaging in patients with locally advanced rectal cancer after neoadjuvant chemoradiotherapy

Abstract

Objective: To explore the value of transrectal ultrasonography (TRUS) for tumor node metastasis (TNM) restaging for patients with locally advanced rectal cancer after neoadjuvant chemoradiotherapy (neo-CRT).

Methods: One hundred and forty-nine patients with locally advanced rectal cancer (cT3-4 or cN+) who underwent TRUS after neo-CRT were retrospectively reviewed. TRUS restaging was compared with the results of post-operative pathological TNM findings.

Results: After neo-CRT, the accuracy of TRUS for diagnosing T-staging was 30.9%, with 60.4% (90/149) of cases overestimated. The sensitivity of TRUS for T-staging (T0 vs T1 vs T2 vs T3 vs T4) were 16.3%, 0%, 12.5%, 42.6% and 75.0%, respectively. The accuracy of TRUS for diagnosing N-staging after neo-CRT was 81.2%, with the sensitivities of N0 and N+ were 93.3% and 31.0%, respectively. After neo-CRT, 27.5% (41/149) of patients achieved pathologically complete response (pCR). The sensitivity, specificity, positive predictive value and negative predictive values of TRUS for pCR were 17.1%, 99.1%, 87.5% and 75.9%, respectively.

Conclusions: TRUS can be applied for restaging T4 and N0, and has potential for screening out patients with pCR in those with locally advanced rectal cancer after neo-CRT, although some stages are overestimated for T-staging and its sensitivity for predicting pCR is low.

Keywords: Rectal cancer; TNM restaging; neo-chemoradiotherapy (neo-CRT); transrectal ultrasonography (TRUS).

Fig. 1.

The neoplasm infiltrated through the intestinal wall and invaded to the serosa layer, with a hypoecho node of 0.5 cm diameter; TRUS restaged for uT4N1. The post-operative pathology staged for ypT4N1.

Fig. 2.

The neoplasm invaded the full-thickness of the intestinal wall, without breaking through the serosa layer; TRUS restaged for uT3N0. Post-operative pathology diagnosed the tumor infiltrated to the muscularis propria and staged for ypT2N0.

Fig. 3.

The structure of intestinal wall was complete after neo-CRT, without obvious tumor residual; TRUS staged for pCR (A). Post-operative pathology demonstrated that the tumor was completely regressed, leaving just fibrous tissue without any tumor cells (× 40, hematoxylin-eosin staining) (B).