Role of endorectal ultrasound in the conservative management of rectal cancers

Abstract

Endorectal ultrasonography (ERUS) extends the ability of the clinician to define the clinical features assessed on routine physical examination, and remains the best modality for accurately staging depth of penetration and presumptive nodal status in rectal cancers. The success of conservative management of rectal cancers is predicated on proper patient selection. The preoperative selection of the ideal patient for local therapies can be difficult, and the decision-making process takes into account many critical factors. Careful assessment of the T and N stages is critical in determining the success of conservative therapies, and directing treatment algorithms. Local resections with curative intent are limited to patients with T1N0 rectal cancers, and select patients with T2N0 tumors with favorable pathological criteria. Conservative management may also be extended to patients identified with significant underlying comorbid conditions staged preoperatively with unfavorable T2/T3 lesions, often combined with adjuvant therapies in a palliative setting. In addition, ERUS may have a role in the selection of those patients with more advanced lesions to neoadjuvant chemoradiation, followed by radical resection. Though not clearly defined, ERUS is evolving in its role in the postoperative follow-up of patients treated conservatively for rectal cancers, and can lead to the early detection of local recurrences. The widespread use of ERUS remains limited due to high operator variability and errors in interpretation; however, the role of ERUS in the postoperative management of rectal cancers is evolving and requires further evaluation.

Preoperative Staging of Rectal Cancer: Role of Endorectal Ultrasound

“…Sonographic characteristics of the rectal wall have been well described (1,17). It consists of five layers, three hyperechoic layers separated by two hypoechoic layers (Figure 1).…”

“…The fourth hypoechoic line represents the muscularis propria. The fifth hyperechoic line represents an interface between the muscularis propria and perirectal fat/serosa (17). Good visualization depends on maintaining the probe in the centre of lumen of the rectum and having adequate distension of the water-filled balloon with good acoustic contact with rectal wall.…”

The Changing Role of Radiation in the Post-TME ERA of Rectal Cancer

“…Accuracy in determining depth of tumor invasion is between 69 -90% and involvement of lymph nodes with cancer is approximately 64 -80% [55][56][57][58][59]. The limitations noted with the use of ERUS, as is the case with all ultrasound diagnostic modalities, are user reproducibility and the steep learning curve.…”

Câncer ano-reto-cólico: aspectos atuais III - câncer de reto - terapêutica neoadjuvante

“…Outro aspecto limitante é a experiência do examinador 47,50 , e eventual uso de irradiação antes do exame ultrasonográfico 51,52 . Quando se trata da avaliação dos campos fora do tumor e, portanto, das metástases locais (envolvimento nodal) a acurácia do ultra-som endorretal varia entre 70-75% 53,54 , melhor que a tomografia e que a ressonância magnética 45,55,56 .…”

“…Sempre vai haver os casos que escapam da eficiência dos aparelhos, acrescidos dos que podem surgir, por um fato, talvez passageiro, mas fator limitante para o uso do ultra-som, que é a significativa variabilidade e erros de interpretações do operador 50,51 , e a possibilidade real da existência de metástases além da capacidade física de detecção do aparelho.…”