Surgery for Rectal Cancer

When it comes to cancer of the lower digestive tract, it can sometimes be referred to as colorectal cancer or bowel cancer. These terms collectively refer to cancer of both the colon and rectum, even if it might be the case that you have one and not the other. In most cases of cancer of the colon and rectum, surgery is one of the curative treatments that are effective in eliminating the cancer.

However, the surgical procedures involved in rectal cancer differ from that of colon cancer due to the site that will be operated on.

The rectum joins directly from the sigmoid colon and consists of the rectal valve and rectum. The rectum can be divided into three vertical sections: high, middle and low sections that are used to demarcate locations of tumors found and the potential surgical sites.

In cases where the bowel passage is blocked, immediate surgery is required. As with other lower digestive tract surgeries, bowel preparation is required before operating on the rectum. This includes bowel cleansing to minimize the risk of infection and ensure that surgeons have a clean and empty bowel to operate on. Removal of stool from the lower gut is usually done through a special diet or the use of laxatives leading up to the day of the surgery.

The type of surgery for rectal cancer is largely dependent on

1. Where in the rectum the cancer is occurring,
2. How large and far it has spread, i.e. the cancer stage based on the TNM system, and
3. The histopathology of the cells following a tissue biopsy.

Doctors will also consult MRI scans of your rectum to determine the type of surgery that would be most effective in removing the tumor with a clear margin of healthy tissue.

In some cases, surgery together with adjuvant chemotherapy or radiotherapy may be required to completely kill the cancer cells present. This can be determined based on a post-surgery tissue biopsy.

For cancers occurring in the early stages where the tumors are relatively small, surgery to remove the tumors and part of the surrounding tissue can be done by inserting special surgical tools directly through the rectum from the anus. This is possible only if the tumor is located in the lower portion of the rectum.

For cancers found in the lower to middle sections of the rectum, small incisions are made in the abdomen, anus and sphincter muscles in order to remove the lower middle portion of the rectum. The remaining healthy cut ends are joined.

As suggested in the name, a low anterior resection is required to remove cancer occurring in the upper rectum through incisions made in the abdomen. Like most cases of partial rectum removal, the remaining sections of the rectum are joined with the sigmoid colon.

For cancers that occur high up the rectum, transanal endoscopic surgery or microsurgery is usually required. These cancers may be large or difficult to reach due to their occurrence in the upper rectum, making a local resection or excision difficult to carry out. In this case, the procedure is similar to a polypectomy, where a colonoscope is inserted into the rectum via the anus, and the tumor is removed by inserting incision tools through the colonoscope.

A total mesorectal excision is one of the most common rectal surgeries done. This involves removing not only the tumor and some surrounding tissue, but also the fatty tissue known as the mesorectum that is found around the rectum. The blood vessels and lymph nodes found in the mesorectum can be examined for metastatic cancer.

In more severe rectal cancers, a complete removal of the rectum may be required through abdominal incisions. The colon is joined with the anus in a procedure known as coloanal anastomosis, sometimes referred to as a coloanal pull-through. A temporary stoma may be required after the operation to allow the organ time for recovery.

Compared to colon cancer surgeries, rectal surgeries are considered less invasive as most will only require a small incision in the abdomen at the most. However, it may become possible to complete rectal surgery without the need for any incisions.

TAMIS, which stands for transanal minimally invasive surgery, is a robotic surgery where instruments are inserted through a port in the anus. The catch? The procedure only works for small early-stage rectal cancers, though most patients do not require overnight hospitalization and can return home on the same day.