How Can We Identify Tumour Penetration?

Abstract

Tumour penetration is seen as the depth of invasion through the layers of the bowel wall and into the surrounding mesorectum. It is an important component of the staging system during assessment of rectal cancer. Historically, the Dukes’ staging system has been used to risk-stratify patients and influence treatment decisions. In addition to tumour depth, it includes assessment of local lymph-node infiltration. In recent years with increasing use of oncological therapy to accompany surgical treatment of rectal cancer, traditional staging systems have been found lacking in detail. The UICC TNM classification has largely replaced the Dukes’ staging system, although many pathologists still report both. Stage at presentation strongly influences prognosis and, in particular, tumour depth. The risk of recurrence for stage T1, T2 and T3 independent of lymph-node involvement is 5%, 10% and 25%, respectively (Sobin et al. TNM classification of malignant tumours, 5th edn. Wiley, New York, p xxiii, 227 p, 1997). As the trend has shifted away from adjuvant therapy to neoadjuvant therapy due to improved outcomes and less morbidity, staging information on the tumour is ideally needed at an early stage in the diagnosis. Accurate tumour stage is important in determining the appropriateness of preoperative chemoradiotherapy (CRT), which has been shown to improve overall outcomes in more advanced tumours. Sufficient detail cannot be obtained from biopsies alone.