Endoscopic Ultrasound Scanning and Contrast Enhancement for Staging and Evaluation of Angiogenesis of Left Sided Colon Cancers

Introduction Background: Colorectal carcinoma represents a global health burden being the most common cancer of the digestive tract. The lifetime risk of developing colorectal carcinoma is 5%, while the overall number of patients currently alive with diagnosed disease in Denmark is estimated to be 30.000 patients. Approximately 70% of cases involve the colon, with the remaining 30% involving the anus and rectum. The mortality rate is intimately related to its high metastatic ability and therefore prognosis strongly depends on the stage at diagnosis.

Angiogenesis: Angiogenesis plays an important role in tumour growth and its metastatic potential and it has been attracting a lot of attention in the past years, due to possible implications in prognosis stratification, as well as in the targeted treatment of advanced colorectal cancer. Most cancers depend firmly on the development of a new capillary network to allow nutrition of newly formed tumour cells. These newly developed blood vessels are usually highly permeable and allow the access of tumour cells in the general circulation, leading to metastatic progression. Current treatment strategies for patients with advanced colorectal cancer include a combined regimen of cytotoxic and biologic therapy targeting angiogenesis. Thus, there is a great interest in finding alternative imaging tests for assessing the efficacy of antiangiogenic agents earlier in the course of therapy, based on functional imaging of tumour vascularity. The benefit that is seen in the survival of patients with advanced disease by treatment with antiangiogenic drugs can maybe translate in a neoadjuvant setting or an adjuvant setting in patients with stage III cancer or high risk stage II cancer.

Staging: Tumour is described by the TNM classification of malignant tumours (TNM).

Accurate preoperative staging of colon and rectum cancer is the main factor determining the treatment modality for patients and can greatly influence the results. Prognostication and determination of T stage of colon tumours by using computed tomography (CT) scans have been widely discussed in the literature. Endoscopic ultrasound (EUS) has been suggested the staging tool of choice for rectal cancer, when comparing to CT, yet colonic cancers remain to be investigated.

With the Danish National Bowel Cancer Screening Programme, increasing numbers of early cancers are revealed. During recent years local treatment in patients with rectal carcinoma in situ T0 or (T1/T2N0M0) cancers has become more and more accepted and has opened new avenues in treatment of old, comorbid or in other ways, vulnerable patients. As a result of the screening programme clinicians will naturally be placed in new dilemmas in terms of treatment choices, radical versus local excision, for early colonic cancers. Important issues on colonic cancer excisions, are the intramural extent of invasion and the presence or absence of lymphnode metastasis.