Sphincter Saving Surgeries In Rectal Cancer-To Avoid A Permanent Stoma
Dr. Praveen performs the following sphincter saving procedures for rectal cancer:
- Ultra low anterior resection
- Intersphincteric resection
- TEMS- Trans-anal Endoscopic Microsurgery
- TAMIS-Trans Anal Minimally Invasive Surgery
What is the “rectal sphincter” and what does it do?
Deeper aspects of sphincter mechanism:
The sphincter is formed by two different types of muscles. The inner muscle layer (which is a part of the rectal tube) is not in our control. The outer muscle layer is named levator ani. This muscle is like any other muscle on our limbs and hence can be controlled consciously.
In normal conditions, both these muscles act synchronously. When your rectum is full with fecal matter, the inner muscle contracts to expel it to the outside. This is when you get the urge to empty your bowel. However if the social environment is not suitable you actively contract the outer muscle to control your bowel. Only when the outer muscle is relaxed will you empty your bowels.
To preserve continence at least the entire outer muscle needs to be functional.
When the rectal sphincter is at risk in rectal cancer? Why was permanent stoma offered in rectal cancer surgery?
The rectum is divided into 3 parts.Upper , middle and lower based on the distance from the anal verge.
- Lower : 0-5 cm from anal opening
- Mid: 5-10 cm from anal opening
- Upper : 10-15cm from anal opening
The lower third of the rectum forms the anal sphincter mechanism.
The tumors of the upper rectum are sufficiently away from the sphincter complex and hence When rectal cancer surgery is performed to remove cancer in the upper rectum the sphincter mechanism is generally not affected. Hence risk to continence is negligible.
However when cancer is affecting mid or lower rectum the sphincter complex is at risk due to its proximity of the tumour to the sphincter. A cancerous growth can directly involve the sphincter.
Comorbidities like diabetes, hypertension and radiation to rectal cancer also affect the continence of the sphincter.
When an oncologically safe surgery with adequate margins is to be performed for a mid or low rectal cancer the sphincter always comes in the field of surgery (margins of resection). Hence in earlier times for all mid and low rectal cancers entire sphincter complex along with anal canal used to be sacrificed and patient used to end up with a permanent stoma.
How is it possible to preserve rectal sphincter and avoid a permanent stoma now?
In recent times there have been tremendous advancements in the management of rectal cancers which help us preserve the sphincter whenever it is technically possible.
Performance of MRI
It’s mandatory to perform MRI of the pelvis for all rectal cancers. MRI is far superior to CT scan to understand the extent of rectal cancer and its local spread. With MRI we can easily identify both the muscles of the sphincter and whether they are involved by the cancer. As discussed earlier at least the outer muscle i.e. levator ani has to be completely free from tumour involvement to have a realistic chance of avoiding permanent stoma.
Fig 02. MRI Of The Rectum Showing A Tumor In The Upper Rectum
Fig 03. MRI Of The Same Patient Showing Clearly Defined Internal And External Sphincter With A Clear Plane Between The Two
Neoadjuvant treatments with radiation and chemotherapy: radiation and chemotherapy before surgery
Invariably all the cancers involving the lower rectum and threatening the sphincter need radiation before surgery. Chemotherapy can also be added. These modalities reduce the size of the tumour significantly. This greatly helps in preserving the sphincter.
Enhanced surgical knowledge and expertise
Pelvic space is a confined space which offers limited maneuverability. With the enhanced knowledge and superior training it is now possible to operate in deep pelvis with precision.
As our understanding of rectal cancer has evolved there has been significant change in surgical thinking. As thought earlier , we have now realized that wide surgical removals at the cost of sphincter sacrifice is not always necessary.
Laparoscopic and robotic surgical techniques
Pelvis is a narrow space stuffed with vital structures- rectum, urinary bladder, uterus( in females), prostate,seminal vesicles( males), major blood vessels and nerves to all these organs. Safe rectal cancer surgery should also preserve the other vital structures. Lap and robotic platforms give superior vision to achieve surgical precision. This is vital in confined space like the pelvis with narrow margins of error.
Fig 04. Port Positioning For Robotic – Ultra Low Anterior Resection And Intersphincteric Resection
Fig 05. Robotic Setup For Rectal Cancer Surgery
Is it possible to preserve sphincter always? Can a permanent stoma be avoided always?
If the out muscle of the sphincter is involved ( levator ani) by cancer, its removal becomes necessary to achieve complete clearance of the tumor. Hence sphincter preservation is not possible whenever levator ani is involved and the patient ends up with a permanent stoma.
Old age patients, long standing diabetes, females above 60 years have poor sphincter function. Hence ,though technically possible to preserve the sphincter structure in such cases , it is not recommended due to poor functional outcomes that affect the quality of life.
What kind of surgeries can preserve my rectal sphincter?
Ultra low anterior resection – in this surgery most of the sphincter is preserved.
Intersphincteric resection – inner muscle layer of the sphincter is removed to various extents in this surgery.
What are TEMS and TAMIS?
These are surgical procedures performed for early rectal cancers that are close to the anal opening ( upto 7-8cms from anal opening).
These procedures are performed through the anal opening using a specialized scope (rectoscope) and equipements.
These techniques are suitable for rectal cancers that have not spread to the muscle layer of the rectal tube.( T1 tumours)
Will I still have a stoma when I undergo these surgeries?
Yes. You will have a temporary stoma to aid the healing of the surgical wound. This stoma will be reversed 4-6weeks after the surgery.