Rectal Cancer Surgery
Anatomically, the rectum begins at the 3rd sacral vertebra and surgically the rectum begins at the sacral promontory. The rectum is different from the colon and is measured at a length of approximately 12 cm to 15 cm. Rectal cancer develops within about 12 cm of the anal verge.
Transanal excision – The procedure is carried out for patients with early stage I cancer. Local excision is possible for lesions that are < 3 cm in size. The lesions are within a third of the circumference of the rectum and well within 8 cm of the anal verge. Polypoid and low-grade, they are mobile and superficial T1 and T2 tumours. ERUS is performed preoperatively and excision of the lesion is carried out along with the full thickness of the rectal wall. A 1 cm margin of normal tissue is left and the defect closed.
Transanal endoscopic microsurgery – TEM uses a special proctoscope to insufflate carbon dioxide and distend the rectum. This helps easy passage of surgical tools into the rectum to address lesions that are located in the distal sigmoid colon and higher up into the rectum.
Endocavitary radiation – A large dose of external-beam radiation therapy can be performed on small areas with lesions < 3 cm. Location should be within 10 cm of the anal verge. A proctoscope delivers endocavitary radiation after sedation.
Other procedures are LAR, APR and CAA.
LAR – lower anterior resection – for patients who do not have any pre-existing sphincter issues and for lesions located in the middle third of the rectum.
APR – abdominal perineal resection – patients at a risk of losing anal sphincter function due to negative margin resection.
CAA – colo-anal anastomosis – performed to avoid permanent colostomy.
Colon cancer surgery
Etiologies for colon cancer are inflammation of digestive tracts, genetics, environment and dietary factors. Preoperative workups usually include colonoscopy, sigmoidoscopy, double-contrast barium enema and biopsy of any suspicious lesions. Surgery is the only curative option for colon cancers Stage I – III. Adjuvant chemotherapy is a necessity for patients at stage II and III cancers.
Right hemicolectomy – performed for lesions located in the right colon and cecum. The right colic, ileocolic and right branch of the middle colic are removed.
Extended right hemicolectomy – division of the right colic, ileocolic and middle colic vessels is conducted to remove the specimen along with the mesentery.
Left hemicolectomy – lesions located at the left colon and splenic flexure are excised with a left hemicolectomy.
Sigmoid colectomy – for lesions located in the sigmoid colon; division of the inferior mesenteric artery is carried out at its origin; to obtain adequate margins, the dissection proceeds down up to the pelvis.
Total abdominal colectomy – is required for patients with attenuated familial adenomatous polyposis (FAP), hereditary nonpolyposis colon cancer syndrome (HNPCC) and metachronous cancers in separate colon segments.
Colon and rectal surgeries are complex decision-making processes. Dr. Deepak gives strong considerations and provides an optimal treatment plan for patients detected with colon and rectal cancer. Intestinal continuity for colon and rectal cancer depend on the extent of tumour and other patient-related factors.