Rectal Cancer

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Overview

Rectal cancer develops when the cells that line the rectum start to divide and multiply uncontrollably. The last six inches of the large intestine forms the rectum and carries faeces until it is expelled. Colon cancers and rectal cancers are often grouped and are together called colorectal cancers.

Non-cancerous polyps, which are abnormal masses of benign cells, are a common precursor to rectal cancer. Rectal cancer is a slow-growing disease that is usually limited to the rectum. It can, however, spread to other organs if left undetected and untreated.

Types

Based on the type of cells that they originate from, rectal cancers are categorised into the following types:

1. Adenocarcinomas: Adenocarcinoma is the most common type of rectal cancer. Adenocarcinomas arise from the cells found in the inner lining of the rectum.
2. Carcinoid Tumours: Carcinoid tumours form in the hormone-producing cells present in the colon region.
3. Gastrointestinal Stromal Tumours: Basically, these are soft tissue sarcomas that arise from the cells of the rectum. This type of rectal cancer is of rare occurrence.
4. Lymphoma: Lymphoma of the rectum is another rare type of rectal cancer.

Symptoms

Rectal cancer is found to manifest itself in a variety of ways, all of which necessitate medical attention. However, this cancer type might exist without causing any symptoms, emphasising the significance of regular screening tests.

Following are some of the symptoms of rectal cancer:

Blood in stools
Diarrhoea, constipation or any other change in the bowel habits that lasts for more than two weeks
Abdominal pain and cramping
Having a persistent urge to have a bowel movement
Unexplained weight loss
Extreme fatigue
Anaemia

Courses

Rectal cancer normally develops over several years, beginning as a polyp, an abnormal cell mass. Some polyps have the potential to develop into cancer and grow and enter the rectum’s wall. Over the years, the researchers have identified a few risk factors for rectal cancers:

Age: The risk of rectal cancers increases with age
Family History of Colorectal Cancers: Those with a family history of colon cancer or rectal cancer are at a higher risk of getting rectal cancer.
Red meat Consumption: Excessive consumption of red meat, a high-fat diet and processed meat increases the risk of rectal cancers.
Personal History of Polyps and Colorectal Cancers: Those who have received treatment for polyps and colorectal cancers in the past are at a higher risk of developing rectal cancers.
History of Bowel Syndromes: Individuals diagnosed with bowel disorders, such as ulcerative colitis, Crohn’s colitis, etc., are prone to develop rectal cancers.
Smoking: Smoking increases the risk of rectal cancers.

Diagnosis

If any of the symptoms discussed above are observed for more than a few days, the doctor may recommend a screening test to check for the signs of rectal cancer. Following are the screening and diagnostic tests available for the detection of rectal cancers:

a. Faecal Occult Blood Test: The faecal occult blood test (FOBT) is a normal screening procedure recommended for colorectal cancers. This test looks for hidden (occult) blood in stool samples. Blood in the stool could be a sign of colon cancer or polyps in the rectum; however, not all tumours or polyps bleed. This test can only detect the presence or absence of blood; it can’t tell the reason for the bleeding. If this test confirms bleeding, additional tests to determine the cause of bleeding should be performed.

b. Digital Rectal Examination: If a rectal tumour is suspected, a digital rectal examination may be recommended, during which the doctor may insert a lubricated, gloved finger through the anus to check the tumour. It is important to note that not all rectal tumours can be observed this way and therefore, additional tests are necessary.

c. Colonoscopy: During a colonoscopy, a flexible endoscope (colonoscope) with a light source and a video camera is inserted into the rectum through the anus. Before the scan, the patient is sedated. This scan helps doctors look for polyps throughout the regions of the rectum and colon. If any polyps are found, a biopsy sample may also be collected and sent for further analysis.

d. Imaging Tests: Imaging tests, such as chest X-ray and CT scans may be recommended for the regions of the abdomen and pelvis if the doctor suspects metastasis.

e. CEA (carcinoembryonic antigen) Test: CEA is a tumour marker produced by tumours and they can be detected in the blood. High CEA levels may indicate rectal cancer; however, this shouldn’t be considered as a conclusive test as many other conditions also lead to high CEA levels. This test is sometimes used to gauge the treatment response shown by rectal cancer patients.

Treatment

The treatment plans for rectal cancer are devised based on multiple factors, such as:

If the tumour has penetrated deeply into the rectum’s wall
Whether or not the nearby lymph nodes appear to be cancerous
If cancer has metastasised
The exact location of the tumour
The patient’s age
The patient’s overall condition

There are multiple treatment options available for rectal cancers and the key ones include surgery, radiation therapy and chemotherapy.

a. Surgery: Surgery is performed to remove the tumour and a small margin of the healthy tissues that surround the tumour. Depending on the stage of the disease, there are multiple surgical procedures opted for the treatment and management of rectal cancers:

Polypectomy: During a polypectomy, if a polyp is found to have become cancerous, it will be removed through colonoscopy.
Local excision: If the cancer is located on the inside of the rectum, has remained localised and not progressed into the rectum’s wall, it is removed with a small amount of the normal tissues surrounding it.
Resection: If cancer has advanced to the rectum’s wall, the cancerous tissues of the rectum, as well as adjacent healthy tissues, are removed. The tissue between the rectum and the abdominal wall may be removed as well. The lymph nodes around the rectum may also be operated on and examined for signs of cancer under a microscope.
Pelvic exenteration: If cancer has metastasised to nearby organs, the lower portion of the large intestine, the entire rectum, anus and bladder are all removed. The cervix, vagina, ovaries and lymph nodes in the surrounding area may all be removed in women. Prostate removal may also be considered for men if the cancer is aggressive. In these cases, the surgeon makes an incision in the abdomen and joins the remaining colon to it (colostomy). Waste exits the body through this opening and accumulates in an abdomen-attached bag.

b. Radiation Therapy: Both external beam radiation therapy and internal beam radiation therapy (brachytherapy) are used to treat rectal cancers. In the case of external beam radiation therapy, the radiation beams are delivered through an external radiation source; whereas, during brachytherapy, a radiation source is placed inside or very close to the tumour. The radiation emitted by this radiation source gradually kills the cancer cells.

In advanced-stage rectal cancer cases, radiation therapy may be recommended to ease pain and other disease-related symptoms.

c. Chemotherapy: Chemotherapy is one of the main treatment options recommended for rectal cancers.

In rectal cancer patients, chemotherapy may be recommended after surgery to eliminate any cancer cells that would’ve survived the procedure. Before surgery, chemotherapy and radiation therapy may be recommended in combination in order to shrink tumours that are large in size so that it is easier to remove it with surgery.

Chemotherapy can also be used to treat symptoms of rectal cancer that has progressed to other parts of the body and cannot be removed with surgery.

d. Immunotherapy: In a few rectal cancer cases, immunotherapy is recommended. Immunotherapy is a cancer treatment modality that stimulates the patient’s own immune system to combat the disease. During immunotherapy, specialised drugs either synthesised by the body or in the laboratory are used to strengthen and restore the body’s natural defences against cancer.

e. Targeted Therapy: Targeted therapy is a sort of treatment that identifies and attacks specific vulnerabilities present on the cancer cells through specialised medication. Targeted therapy is a form of precision medicine as it precisely targets the cancer cells while sparing the normally functioning cells.

Frequently Asked Questions

1. Are rectal cancers treatable?

Yes, rectal cancers can be treated. If detected in the early stages, this cancer can be treated with excellent clinical outcomes and the quality of life isn’t much affected either.

Just like any other cancer, it is important for rectal cancers to be detected in their early stages. If you are a high-risk individual, you may consider regular screening for rectal cancer, which may help in the prevention and early detection of the disease.

2. Does rectal cancer spread fast?

Rectal cancer, in most cases, begins as an adenomatous polyp, a mass of benign cells. The majority of these polyps are non-cancerous, however, some may become cancerous over the course of 10-15 years.

When cancer develops in the rectum, the rate at which it grows and spreads depends on its grade and other factors like the patient’s overall health, lifestyle habits, etc.

3. What are the side effects of rectal cancer?

The side effects that each patient experiences depend on the treatment given. Surgery may lead to side effects such as bleeding and pain where the incision was done, tiredness, feeling of sickness, swelling, bruising, etc.

Chemotherapy may cause hair loss, mouth sores, nausea and vomiting, loose stools, nerve damage, tiredness, infection, etc.

Radiation therapy may also lead to certain side effects, namely skin irritation, loss of appetite, loose stools, etc.

In most cases, patients may experience bowel dysfunction. The doctor may recommend a few changes in your food habits until the bowel function improves.

Most of these side effects go away gradually. However, if managing these side effects becomes difficult, patients can reach out to the doctors for help.

4. Can I check myself for rectal cancer?

Yes, there are screening methods available for rectal cancers. In most cases, colonoscopy is recommended for rectal cancer screening.

Before the procedure, the patient is sedated. A colonoscope, which is a flexible, lighted tube, is introduced into the rectum after sedation, and the entire colon and rectum region is checked for polyps or cancer.

Rectal screening is strongly recommended for high-risk individuals, i.e., for those with a family history of colorectal cancers, personal history of colorectal cancers, those having inflammatory bowel syndrome, etc.

5. How can I prevent rectal cancer?

Although you cannot prevent rectal cancers completely, here are a few things that you can do to reduce your rectal cancer risk:

Avoid frequent consumption of red, processed meat
Maintain a healthy weight
Quit smoking
Avoid excessive alcohol consumption
Maintain an active lifestyle