Overview of Rectal Cancer Microsurgery
Colorectal cancer, which impacts the colon and rectum, is the third most common cancer in both men and women. It’s also the second most common cause of death from cancer in the United States. The current data often groups together colon cancer and rectal cancer, so it can be hard to tell how many cases are specifically rectal cancer.
If a person is suspected to have rectal cancer, the doctor will confirm a diagnosis by examining tissue under a microscope to look for cancerous cells, known as adenocarcinoma. The treatment plan depends on what type of cells are causing the rectal cancer. If the cells are squamous cell carcinomas, the treatment might be different.
Generally, the doctor removes a sample of the cancerous tissue (called an excisional biopsy) only if they believe it can be done safely and completely, with the goal of curing the patient of their cancer. In some cases, the doctor might perform a local excision. This is a procedure where a surgeon removes only a small area of tissue. It’s typically only done for very specific patients with a certain stage (cT1N0) of the disease who have other medically favorable characteristics. More advanced cases may require a transanal excision if they aren’t suitable for traditional surgery.
A local excision has certain benefits, like lower risk and minimum complications. But it also has some downsides, as it may not remove all of the cancer or provide enough information for proper staging (which is how doctors determine how much cancer is in the body).
Imaging tests like MRIs help the doctor understand how far the cancer has spread, including whether it’s invaded the rectal wall (Tis, T1, or T2). But these tests don’t always provide a full picture, so doctors often also use endoscopic ultrasonography (EUS), which is more precise and detailed.
When it comes to rectal adenocarcinoma, the best treatment approach depends on different factors, mainly the tumor’s location in the rectum and how far it has spread. Surgery is typically the only way to fully cure rectal cancer. This usually involves removing the entire rectum with safety margins and performing a total mesorectal excision (TME), which also removes local lymph nodes. This can either be done through a low anterior resection or an abdominoperineal resection.
A minimally invasive surgery called rectal microsurgery is used to treat early-stage rectal cancers. While total mesenteric excision (TME) was historically the go-to method, its high complication rate and impact on patient’s quality of life prompt consideration for other methods in early disease.
The conventional method called transanal excision (TAE) has its limitations especially difficult to reach rectal tumors, making transabdominal resection often the only effective option.
As more cases of rectal cancers are detected early due to increased screening, there’s more interest in developing methods that preserve as much of the rectum as possible. The transanal endoscopic microsurgery (TEMS) method, developed in the 1980s, is a minimally invasive surgery that removes rectal tumors but is typically only used for lower stages of rectal cancers. Another newer method, transanal minimally invasive surgery (TAMIS), provides another option for minimally invasive treatment.
Lastly, endoscopic submucosal dissection (ESD) can remove cancerous tissues within the rectum and colon. It’s another option to consider for early-stage rectal cancer based on the local medical expertise with this technique.
Anatomy and Physiology of Rectal Cancer Microsurgery
The rectum is an intricate part of our body that plays a major role in our digestive system. It’s important to have a good understanding of how it works, especially when it comes to rectal surgery.
The rectum is a separate part within the large intestine, commonly known as the colon. It measures about 15cm and acts like a bridge connecting the last part of the digestive tract to the anus, which is where waste leaves the body. The junction between the sigmoid colon (a part of the large intestine just before the rectum) and the rectum doesn’t have the pouch-like appendages usually found in the rest of the colon.
You could think of the rectum as having three segments – top (12-15 cm from the anus), middle (7-11 cm from the anus), and bottom (up to 6 cm from the anus). The top part pushes digested food down like the rest of the colon, while the bottom part widens a bit to store waste until it’s ready to leave the body.
Relationship-wise, the upper part of the rectum is surrounded by a part of the peritoneum, a protective layer that also covers structures like the bladder and ureters (tubes that carry urine) in both men and women. In men, it forms the rectovesical pouch, while in women it extends covering parts involved in reproductive functions forming what we call the pouch of Douglas.
The rectoprostatic fascia (also known as Denovillier’s fascia) is a sheet-like structure found between the rectum and the prostate and seminal vesicles in men, within which lie the hypogastric nerves and small blood vessels supplying the male reproductive organs.
The presacral fascia or Waldeyer’s fascia is present behind and below the rectum and basically helps in holding the rectum to the sacral bone.
The rectum is surrounded by a layer of fat tissue known as the mesorectum, which contains the blood vessels, lymph vessels, and nodes responsible for immunity. Surgical removal of the rectum often involves careful dissection in the relatively blood-free space between the mesorectum layer and the pelvic fascia, a structure that lines the pelvic cavity.
The rectum gets blood supply from three main arteries. The majority of blood, about 80%, is supplied by the superior rectal artery. The rest of the supply comes from branches of another blood vessel lower down the pelvis, leading to the middle rectal artery and internal pudendal artery. Similarly, vein drainage involves three veins – superior, middle, and inferior rectal veins, draining respective parts of the rectum. The lymph glands are present throughout the rectum and aid in immune response.
The rectum is controlled by both sympathetic and parasympathetic nervous systems. The nerves that control functions like going to the toilet and sexual functions travel through a complex network called the inferior hypogastric plexus. Damage to this area can cause serious bladder and sexual problems.
Why do People Need Rectal Cancer Microsurgery
Transanal excision is a medical procedure used for removing certain benign, non-cancerous growths (polyps) or early-stage cancers in the rectum. This is suitable for small, movable conditions that take up less than one-third of the rectal circumference. Here, the ‘small’ condition would often be less than 3 cm in size to provide enough space for the doctor to work. A more experienced surgeon may remove larger growths using specialized techniques known as TEM (Transanal Endoscopic Microsurgery) or TAMIS (TransAnal Minimally Invasive Surgery), but these might be a bit risky.
The transanal excision process is useful for treating early-stage rectal cancers, specifically T1N0. This type of cancer is further divided into sm1, sm2, and sm3. They are named based on how deep the abnormal cells have spread into the mucous membrane lining the rectum. For cancer to be categorised as sm1, it would have spread less than 1000 micrometers beneath the membrane’s surface. The chances of cancer spreading to nearby lymph nodes are very minimal. However, for sm2 and sm3, the cancer has spread more than 1000 micrometers beneath the surface, increasing the risk of spreading to lymph nodes and possibly recurring.
Considering these risks, the European Society for Medical Oncology suggests using the transanal excision technique only for sm1 rectal cancers. For more severe instances of cancer, like sm2 and sm3, a more comprehensive surgical treatment called ‘total mesorectal excision’ would be appropriate.
In addition to early cancer or benign growths, transanal excision can be used for other less severe conditions such as rectal polyps, solitary rectal ulcers, constriction of the rectum (rectal stenosis), or rectal prolapse, where the rectum slides or falls out of place.
When a Person Should Avoid Rectal Cancer Microsurgery
Sometimes, a surgeon can’t perform a specific type of operation called transanal microsurgery due to certain factors related to the tumor’s size and location.
If the tumor is very low in the rectum, less than 5 cm from the anal opening, it may be challenging to remove because the surgical instrument or “transanal port” obscures it.
Also, if the tumor takes up more than 30% of the space inside the rectum or is bigger than 3cm, surgery may not be advised, although this largely depends on the surgeon’s expertise.
However, if the tumor has any of these characteristics, it could make the surgery difficult, possibly resulting in less favorable results in terms of cancer treatment.
Equipment used for Rectal Cancer Microsurgery
Transanal Endoscopic Microsurgery (TEMS)
This surgical technique was the first of its kind. It was developed in 1983. The procedure uses a special tool called a proctoscope that has a flat or slightly angled end. This device is quite large with a diameter of 40mm and a length of 12 or 20 cm. This tool is carefully inserted into the rectum and then sealed off with a faceplate. The faceplate has several ports for inserting a special system of lenses (a stereoscopic optics system) and other surgical instruments. This lens system allows the surgeon to see in three dimensions, which helps them judge distances accurately during surgery. The rectum is kept inflated with air to create room for the surgeon to operate. This is done using a machine that pushes air into the rectum and controls the pressure inside it. The entire set-up is firmly attached to the operating table with a support arm.
Transanal Minimally Invasive Surgery (TAMIS)
This surgical technique was introduced in 2010. It uses a flexible port with multiple channels for inserting standard laparoscopy instruments. The port was adapted from two other tools, the SILS Port and GelPOINT PATH. These tools introduced a new platform for surgery that prioritized minimal invasiveness and reduced recovery time.
Insufflation
In both TEMS and TAMIS procedures, it is crucial to keep the rectum inflated with air. This process, known as insufflation, provides a clear space for the surgeon to operate. Typically, pressures of 12 to 15 mmHg are applied in these types of microsurgeries. With TEMS, a specially designed unit uses carbon dioxide to inflate the rectum and keeps the pressure at a safe and stable level. It can also suction or extract air when needed. On the other hand, TAMIS uses a special gel seal cap with a port that allows carbon dioxide to inflate the rectum. Recently, an innovation called Airseal has been implemented in TAMIS. It’s a device that controls the flow of gas, making it easier to maintain the right pressure by inserting carbon dioxide and removing smoke during the procedure.
Who is needed to perform Rectal Cancer Microsurgery?
The main medical team in the operating room includes the surgeon, a surgical assistant, an anesthesiologist, and a scrub nurse. The surgeon is a doctor who performs the operation, and the surgical assistant helps the surgeon during the surgery. The anesthesiologist is responsible for making sure you are asleep and comfortable during the operation. The scrub nurse helps prepare the tools used during your surgery. There may also be other team members present to help get you ready for the surgery, assist in giving you anesthesia, or to get any necessary equipment during your surgery.
Preparing for Rectal Cancer Microsurgery
Before having surgery on the rectum, patients need to undergo several medical check-ups, known as a pre-operative work-up. This work-up helps to ensure that the procedure is as safe and effective as possible. One of these check-ups may include a full colonoscopy. This is a test that investigates the inside of the colon to make sure there are no other issues that need to be addressed. Doctors need to know the exact location and size of the rectal lesion, a word used to describe a growth or abnormality, before it can be removed.
Next, doctors use a combination of MRI and endoscopic ultrasounds to study the lesion. They also take CT scans of the chest, abdomen, and pelvis to make sure the disease hasn’t spread to other parts of the body. When it comes to taking a sample of the lesion for testing, doctors proceed with caution because the procedure can risk spreading the cancer cells and making future surgeries more challenging.
By studying the lesion closely, doctors can create the best treatment plan for the patient. Rectal microsurgeries can cure low-risk rectal cancers, but the treatment plan is different for aggressive cancers that have deeply invaded the surrounding tissue – these are at a higher risk of coming back. This is why a team of surgical specialists, radiologists, and pathologists discuss and decide if it’s better to conduct the initial biopsy or to proceed directly with the surgery to remove the lesion.
If a patient is diagnosed with early rectal cancer, specialists like cancer care nurses are available to provide support and detailed information about the operation and recovery phase. Some patients may also need to speak with a stoma nurse, who can provide advice and reassurance, even though the likelihood of needing a stoma is low.
Before the day of the surgery, patients may need a full bowel preparation to empty the bowel and provide the doctor with optimal access to the lesion. The patient’s surgeon may also decide to give the patient preventative antibiotics and medication to prevent blood clots. After the surgery, most patients stay in the hospital for a day or two. Patients may feel some discomfort or pain, but this typically goes away quickly. Patients are usually encouraged to start eating solid foods immediately and may require help from a dietitian to adjust their meals temporarily to ensure their nutritional needs are met.
How is Rectal Cancer Microsurgery performed
Two types of procedures—Transanal Endoscopic Microsurgery (TEM) and TransAnal Minimally Invasive Surgery (TAMIS)—require different positioning depending upon where the growth (lesion) is located. These surgeries are used to remove benign (non-cancerous) and malignant (cancerous) tumors in the rectum, the last section of the large intestine.
In a TEM procedure, your position during surgery will vary based on where the lesion is located. Your surgeon will set you up to ensure the lesion is ‘down’ relative to the angled viewing device attached to the surgical tool, with the angled side facing downward. For growths on the front wall of your rectum, you might need to lie on your stomach. For growths on the back wall, you may lie on your back or have your legs raised and spread apart in a lithotomy position (like women during childbirth). For growth on the sides, you may need to be tilted to the right or left side.
With TAMIS, there’s more flexibility as the surgical instrument can move and provide visibility in all directions. No matter where the lesion is, you will generally be put in the lithotomy position. However, in some cases, if the growth is towards the front and in the upper part of your rectum, your surgeon might prefer you to lie on your stomach.
In the resection phase of these surgeries, a surgical tool that uses electricity, a diathermy, is used to draw a border around the lesion that’s 10 to 15 millimeters away from it. The surgeon will usually start carving out the lesion from the bottom, going around it in a circular pattern, moving upwards. If the growth is cancerous, all layers of the rectal wall down to the outer fatty tissue need to be removed. The resulting hole in the rectal wall is stitched up with dissolvable sutures, done in a sideways (transverse) manner to prevent the rectum from narrowing. The tissue removed is stored in a solution called formalin and sent to a lab to check for cancerous cells.
While doing this, there is a higher likelihood of reaching the space inside the abdomen, especially for those growths that are towards the front and top part of your rectum. If a hole is accidentally created, it can generally be stitched up without needing to access the abdomen. It’s usually recommended to remove all layers of the rectal wall even for benign growths, as these can sometimes have pockets of invasive or cancerous tissue.
Possible Complications of Rectal Cancer Microsurgery
Patients who have a type of surgery called rectal microsurgery often do better and recover more quickly than those who have a more invasive surgery that goes through the abdomen. However, there can still be some issues after rectal microsurgery. One possible issue is having a hard time controlling bowel movements, which can sometimes happen if a large tool called a proctoscope is used during the surgery.
Other common side effects of this surgery can include bleeding, rectal pain, narrowing of the rectum, and inflammation or infection in the pelvic area.
In some rare cases, the surgery might accidentally open up the abdomen, leading to an infection in the abdomen that might require a big surgery to fix. However, rectal microsurgery is considered safe overall and is preferred because patients stay at the hospital for less time and recover faster compared to other similar procedures.
What Else Should I Know About Rectal Cancer Microsurgery?
This article talks about when, how, and why rectal microsurgery is done. Rectal microsurgery is a specific kind of surgery for the rectum, the final part of your large intestine. This surgery uses precise, miniature tools, hence the term “micro”.
Knowing about the different methods and tools used is important for health professionals. It helps them choose the right treatment for each patient. It also lets them explain what will happen during the surgery, what kind of care the patient will need afterwards, and what to expect during recovery.
Recognizing what is normal after the surgery and what could be signs of problems is important. It helps avoid unnecessary tests or delays in finding and treating any potential issues.
