Rectal Cancer

The terminal portion of the large intestine

The rectum extends from the sigmoid colon and ends at the anal canal.

Unlike most of the colon, the rectum is located deep within the pelvis.

It lies close to several important structures, including:

• the bladder and urinary tract
• the genital organs
• the pelvic floor muscles
• the anal canal and sphincters

The rectum is also surrounded by fatty tissue containing blood vessels and lymph nodes: the mesorectum.

This anatomy explains why the work-up and surgery for rectal cancer have important specific features.

Two nearby locations, but sometimes different strategies

Colon and rectal cancers both belong to the colorectal cancer family.

They nonetheless present important differences.

The rectum’s location within the pelvis means the tumor may lie close to:

• the anal sphincter
• the mesorectum
• the bladder
• the urinary tract
• the genital organs
• the pelvic floor

Local assessment must therefore be particularly precise.

For certain rectal tumors, treatment may also be given before surgery to optimize disease control.

→ Learn more about colon cancer

Sometimes subtle symptoms

Rectal cancer can be discovered during screening or a colonoscopy performed for another reason.

When present, symptoms may include:

• blood in the stool
• a persistent change in bowel habits
• frequent or unusual urges to have a bowel movement
• a feeling of incomplete emptying
• a change in stool shape
• fatigue or anemia
• sometimes pelvic discomfort or pain

These symptoms can have many other causes.

Blood in the stool or a persistent change in bowel habits nonetheless deserves medical evaluation.

Colonoscopy and biopsies

Colonoscopy allows examination of the colon and rectum.

When a rectal lesion is identified, biopsies are usually performed.

The samples are then analyzed under a microscope to determine the nature of the lesion.

This analysis confirms the diagnosis and clarifies certain characteristics of the tumor.

Examining the entire colon also makes it possible to look for any other lesions.

A clinical examination of the rectum can provide additional information, particularly when the tumor is low enough to be accessible.

An essential exam for precisely understanding the tumor

Pelvic MRI plays a particularly important role in the work-up of rectal cancer.

It allows precise study of the tumor and its relationship with surrounding structures.

It notably helps assess:

• the depth of tumor extension
• the mesorectum
• the regional lymph nodes
• the tumor’s proximity to the resection margins
• its relationship with the sphincter and pelvic structures when it is low

This information directly contributes to choosing the treatment strategy.

Assessing the disease locally and at distance

The work-up does not stop at studying the rectum.

Chest, abdominal, and pelvic imaging also makes it possible to look for any distant spread of the disease.

Blood tests are performed and may include measuring CEA.

CEA alone cannot diagnose rectal cancer, but it can provide useful information for management and follow-up.

All the results together make it possible to define the stage of the disease.

Not all rectal tumors follow the same pathway

Treatment depends on several factors:

• the tumor’s height within the rectum
• its depth of extension
• the lymph nodes
• its relationship with the mesorectum and neighboring structures
• any possible distant disease
• certain biological characteristics of the tumor
• the patient’s general health

Some early-stage tumors may be suitable for initial surgical treatment.

For other rectal cancers, treatment is given before surgery.

The strategy is therefore defined individually within a multidisciplinary framework.

Reducing the risk of recurrence and optimizing the surgical strategy

For certain locally advanced rectal cancers, or those with specific features on MRI, preoperative treatment may be offered.

Depending on the situation, it may combine:

• radiotherapy
• chemotherapy
• chemoradiotherapy
• or a sequence combining several treatments before surgery

This is commonly referred to as neoadjuvant treatment.

In some situations, all planned chemotherapy and radiotherapy can be administered before surgery: this strategy is called total neoadjuvant therapy, or TNT.

The goal is not simply to “shrink the tumor.”

The strategy notably aims to improve local control and to treat any microscopic disease early.

Removing the diseased rectum along with its lymphatic territory

When rectal resection is indicated, the goal is to remove the portion of the rectum containing the tumor with adequate oncologic margins.

For many mid- and low-rectal tumors, surgery also includes careful removal of the mesorectum surrounding the rectum.

This technique is called total mesorectal excision, or TME.

The mesorectum notably contains the blood vessels and lymph nodes associated with the rectum.

The quality of this dissection is an essential element of oncologic rectal surgery.

Tumor location is decisive

One of the key challenges of rectal surgery is determining whether the tumor can be removed while preserving the anal sphincter.

This possibility depends notably on:

• the tumor’s height
• its extension
• its relationship with the sphincter
• the response to any preoperative treatment
• the ability to achieve a satisfactory oncologic resection
• pre-existing sphincter function

When conditions are favorable, the diseased rectum can be removed and digestive continuity then restored.

In certain very low tumors, sphincter-preserving surgery is not oncologically or functionally appropriate.

Colorectal or coloanal anastomosis

When the sphincter can be preserved, the remaining colon is connected to the remaining rectum or, for very low resections, to the anal canal.

This junction is called an anastomosis.

It can therefore be:

• colorectal
• or coloanal, depending on the level of resection

The goal is to create a well-vascularized digestive continuity without excessive tension.

No, but it can serve several purposes

Whether a stoma is needed after rectal surgery depends on the type of procedure.

When a very low anastomosis is performed, a temporary diverting stoma may be offered in certain situations.

Its purpose is to temporarily divert the bowel while the anastomosis heals.

It can then be closed once the necessary conditions are met.

In other situations, particularly when the tumor requires removal of the rectum and anal sphincter, a permanent colostomy may be necessary.

It is therefore important to distinguish between:

temporary diverting stoma ≠ permanent stoma.

The strategy is discussed individually before surgery whenever possible.

Minimally invasive approaches suited to certain situations

Rectal surgery can be performed via an open approach or a minimally invasive approach depending on the situation.

Laparoscopy allows surgery to be performed using a camera and instruments introduced through small incisions.

Robot-assisted surgery is another minimally invasive approach.

It can notably facilitate certain maneuvers within the narrow space of the pelvis.

The surgeon directly controls the instruments from a console: the robotic system does not perform any maneuver autonomously.

A highly selective option after a complete response to treatment

In some patients who have received preoperative treatment, the tumor may show a complete clinical response, meaning no residual tumor is detectable on the exams used to assess response.

In carefully selected situations, a surveillance strategy without immediate surgery may then be discussed.

This approach is often called Watch and Wait.

It does not mean the patient is simply “left without treatment.”

On the contrary, it requires particularly rigorous oncologic surveillance, combining clinical exams, endoscopy, and MRI at regular intervals.

If local regrowth occurs, surgery may be necessary.

This strategy applies only to selected situations and must be discussed within an experienced team.

Pathology analysis clarifies the disease’s characteristics

The surgical specimen is analyzed by the pathologist.

This analysis notably allows study of:

• the residual tumor
• its depth of extension
• the resection margins
• the mesorectum
• the lymph nodes removed
• the response to any preoperative treatment

This information is combined with the data obtained before surgery to determine the next steps in care.

Bowel function can be altered

After rectal resection with sphincter preservation, bowel function may differ from what it was before surgery.

Some patients may notably experience:

• more frequent bowel movements
• fragmented bowel movements
• more urgent needs
• difficulty delaying evacuation
• a feeling of incomplete emptying

The extent of these changes varies considerably from one patient to another.

It depends notably on the level of the anastomosis, the treatments received, and prior bowel function.

When several of these symptoms occur together, this is sometimes called low anterior resection syndrome, or LARS.

Symptoms can improve gradually, and various measures can be offered when they are bothersome.

Several specialists contribute to the decision

The management of rectal cancer involves several specialties.

Depending on the situation, the case may notably involve:

• gastroenterologists
• radiologists
• colorectal surgeons
• oncologists
• radiation oncologists
• pathologists
• stoma care nurses when necessary

The goal is to build a strategy tailored to the tumor’s location, its stage, and the patient’s individual characteristics.