The malignant polyp – When to operate and when to watch ?

Konference: 2007 XXXI. Brněnské onkologické dny a XXI. Konference pro sestry a laboranty

Kategorie: Kolorektální karcinom

Téma: XVI. Kolorektální karcinom

Číslo abstraktu: 144

Autoři: J. Pfeifer

Colorectal cancer is one of the most leading causes of death in the Western world. Frequency of colorectal adenomas varies according to the studies (if younger people are included or not) between 2% – 35%. Adenomas are thought to be precursors for cancer (adenoma-carcinoma sequence) and therefore should be removed. However, polyps of the large bowel may originate from mucosa or submucosal tissue independant from their behaviour. Histological examination can differentiate between the various benign and potentially malignant forms.

Adenomatous polyps are neoplastic epithelial tumours with no evidence of malignancy. All adenomas are dysplastic by nature but not all dysplastic lesions are adenomas. A malignant polyp is a adenomatous lesion where cancer has invaded by direct continuity through the muscularis mucosa into the submucosa.

The risk of malignant transformation depends on size, degree of dysplasia, the site (colon or rectum) and if the tumour’s appearance is tubulous or villous.

Biopsies of a polyp carries a risk of false negative results of 18.5%. Therefore a whole polypectomy must always be done. When polypectomy is done and the diagnosis of a malignant transformation has been established, several points must be considered: Is polypectomy enough? What are high risk factors, which may require colonic resection? Are there any other relevant factors?

Decision making
An exact level of invasion according to Hagitt’s classification must be stated by the pathologist. Furthermore degree of differentiation, lympho-vascular invasion, completelyness of excision, resection margins and length of pedicle (if less than 3 mm) is important. It should be mentioned that malignant polyps with an unfavourable histology carry a cancer-specific risk of 10%-25%.

Factors against resection
Every colorectal resection has a significant risk of morbidity and mortality. To mention a few: leakage of the anastomosis, diarrhea, stoma complication beside age specific cardio-respiratory complications. The risk of malignant transformation in adenomas is less than 10%, the risk of postoperative death between 2%-10% dependent on age and co-morbidities.

The surgeon, gastroenterologist (endoscopist) and the pathologist must work together to offer the single individual the best available treatment.

Datum přednesení příspěvku: 24. 4. 2007