What Is Colorectal Cancer?

Colorectal cancer is cancer that begins and is found in the colon or rectum. This can be called either colon cancer or rectal cancer, depending on where it develops. Whichever, both colon cancers types and rectal cancer types share a lot in common.

How Does It Start?

The colon and the rectum are both parts of the large intestine of the gastrointestinal system. The colon absorbs leftover salt and water from food coming from the small intestine. The waste then goes to the rectum and is stored until it goes out of the body through the anus.

Most of the time, different types of colorectal cancer develop as abnormal growth on the colon’s or rectum’s lining. This kind of growth is called polyps and can turn into cancer over time. There are various types of polyps, such as the following:

• Adenomatous – Although they are benign, these polyps are considered precancerous conditions because they can become cancer if not removed. The bigger they grow, the more dangerous they are.
• Hyperplastic and inflammatory –These are common but aren’t precancerous. These low-risk polyps, once found, are removed and tested to make sure that they’re don’t cause cancer.
• Sessile serrated and traditional serrated adenomas –These have a high chance of turning to cancer quickly and are dangerous since they’re hard to identify in an endoscopic exam.

Polyps become a risk for colorectal cancer when:

• A polyp grows larger than 1 cm.
• More than three polyps are found.
• Discovery of dysplasia after a polyp is removed. It means there’s an area in the colon’s or rectum’s lining where the cells look abnormal but aren’t cancer yet.

General Signs and Symptoms

General and common symptoms of colorectal cancers include:

• Presence of blood in the stool
• Sudden and unexplained anemia
• Bloating
• Abdominal and pelvic pain
• Vomiting
• Abrupt changes in bowel habits
• Unexplained weight loss

Diagnosis of Colorectal Cancer

Colorectal cancer can be diagnosed through several tests. A person can be diagnosed after showing symptoms or if there’s something abnormal discovered during a screening test. However, the diagnosis process for colorectal cancer generally includes the following tests:

• Imaging tests such as MRI scans, x-rays, ultrasound, PET scan, CT scan, and angiography
• Proctoscopy
• Biopsy
• Blood tests
• Diagnostic colonoscopy (only after showing of symptoms)

Stages of Colorectal Cancer

Cancers are generally clinically described by the stages at which they’re discovered. Stages are determined based on the invasion depth in the intestine wall, involvement of lymph nodes, and spread to other organs. Identifying the cancer stage is important to know how to handle the disease properly. Here are the stages of colorectal cancer:

• Stage 0 – A precancerous stage where the disease remains within the rectum or colon lining.
• Stage I – The cancer has grown in the intestine wall but hasn’t spread beyond the coat or close lymph nodes.
• Stage II – This includes other substages but generally means that cancer has penetrated the muscular layers and has spread through the wall. It hasn’t reached the lymph nodes yet.
• Stage III -An advanced stage of cancer that means it has spread and reached the lymph nodes.
• Stage IV – The last stage means cancer has already spread into distant organs like the lungs, liver, or ovaries.

Common Types of Colon Cancer

Here are the different types of colon cancer commonly found:

Colorectal Adenocarcinoma

The majority of colon cancers is adenocarcinoma, and it’s one of the colon cancer cell types. Adenocarcinoma is a cancer of the cells on the inside lining and surface of the colon or at the end of it, near the rectum. It develops and grows in the epithelial cells that produce mucus that lubricates the insides of the colon and rectum before it spreads to other layers.

There are other two subtypes of adenocarcinoma:

• Signet ring cell -This is relatively uncommon but is a colon cancer aggressive type and can be harder to treat.
• Mucinous – This adenocarcinoma is mainly composed of mucus which causes faster spreading of the cancer cells and is also one of the aggressive colon cancer types, more aggressive than the typical adenocarcinoma.

Most of the time, colorectal cancers refer to colorectal adenocarcinoma since it’s the most common type. Its symptoms include:

• Unexplainable weight loss
• Presence of blood in the stool
• Tenderness and pain in the abdominal area
• Thin stools
• Abrupt bowel habit changes like constipation or diarrhea

If someone is diagnosed with it, they have the following treatment options to choose from:

• Targeted therapy
• Chemotherapy
• Surgery
• Radiation therapy

Gastrointestinal Carcinoid Tumors

These are tumors that develop in the hormone-producing cells in the intestines. Carcinoid tumors start in the nerve cells called neuroendocrine cells that regulate hormone production. These tumor cells grow slowly and can also develop in the lungs aside from the gastrointestinal tract. The carcinoid tumors account for half of the cancer types found in the small intestine but less than 5% of all colorectal cancers.

Depending on where the tumor develops and grows, the potential symptoms vary. It can grow in:

• Small intestine or Colon – This can cause stomach pain and cramps, tiredness, weight loss, bloating, and other stomach problems.
• Appendix – There are no symptoms unless the tumor blocks the pathway connecting the appendix to the intestine. This will result in appendicitis symptoms like vomiting, fever, and nausea.
• Rectum – The tumor can cause bleeding, pain, and constipation.

These tumors can also produce various types of hormones that cause different symptoms. For instance, people with carcinoid tumors can have symptoms like wheezing, flushed face, rapid heartbeat, and diarrhea caused by the hormone-like substances released by the tumor.

There are various ways gastrointestinal carcinoid tumors may be discovered, primarily depending on where they develop. But generally, available treatments include:

• Hormone therapy
• Radiation therapy
• Surgery
• Chemotherapy

Rare Types of Colon Cancer

There are also some rare colorectal cancer types which include:

Gastrointestinal Stromal Tumors (GISTs)

These tumors develop in special cells in the lining or anywhere in the gastrointestinal tract – the interstitial cells of Cajal. These cells are the “pacemakers” of the muscles in the intestine. Most of the time, these tumors develop and grow in the stomach but can also form in the rectum and small intestine. GISTs are also classified as sarcomas which means that they can develop in connective tissues like blood vessels, fat, nerves, bones, cartilage, muscle, and deep skin tissues.

Although these tumors grow pretty slowly, they can still cause bleeding in the gastrointestinal tract, depending on their location. More possible symptoms include:

• Weight loss
• Vomiting
• Abdominal pain and mass or lump
• Difficulties in swallowing
• Nausea
• Poor appetite

However, not all GISTs are cancerous. Some are benign and don’t grow and spread in other areas and parts of the body. Smaller tumors can be treated easily, but others might require surgery or targeted therapy.

Squamous Cell Carcinomas (SCC)

These are extremely rare types of colon cancer and are more associated with skin cancer. But, squamous cells are present in various body areas, and a carcinoma occurs when these cells start uncontrollably growing and turn cancerous.

This is included in the list since SCC symptoms may resemble the ones from colorectal adenocarcinoma like stool, bowel, and stomach problems. That’s why it’s essential to determine whether cancer started in the colon or rectum or other parts instead.

Leiomyosarcomas

Sarcomas can develop in the blood vessels, muscle layers, and other connective tissues in the colon and rectum walls, like GISTs. However, leiomyosarcoma is another form of sarcoma and means cancer of the smooth muscle. This type can affect specific muscles that make three layers of the colon and rectum, guiding waste through the digestive tract.

Early stages of leiomyosarcomas in the colon or rectum may not result in particular symptoms. But as cancer grows more and progresses, potential symptoms may include:

• Weight loss
• Changes in stools
• Fatigue
• Stomach problems
• Vomiting of blood

Treatment typically starts with surgery to remove the tumor but can also be through radiation therapy or chemotherapy.

Lymphomas

Specifically referred to as primary colorectal lymphomas, which are under the type of non-Hodgkin lymphoma. This type of cancer starts in the lymphatic system, especially in the lymphocytes, a type of white blood cell. Generally, lymphomas are cancers of the immune system cells.

A lymphoma can grow in various body parts like the spleen, lymph nodes, thymus, bone marrow, and parts of the digestive tract such as the colon and rectum. This rare type is concerned explicitly with less than one percent of all colorectal cancers and is more common among adults, especially men.

Symptoms of primary colorectal lymphomas can include:

• Stomach pain
• Indigestion
• Diarrhea
• Sudden weight loss
• Bloating
• Vomiting
• Other stomach problems

Treatment options include the most common ones: surgery, chemotherapy, and radiation therapy.

Melanomas

Although associated with skin cancer, melanomas can also develop and grow in the colon or rectum or spread to the gastrointestinal tract from the primary area of growth. Since this is extremely rare, how melanomas develop in the colon is still unclear. But diagnosis focuses on whether cancer started from the rectum or colon or it simply spread to these areas and came from some other parts.

Treatment options for melanomas include:

• Radiation therapy
• Surgery
• Chemotherapy
• Immunotherapy

Risks of History of Colorectal Cancer in the Family

Generic risks exist if a family member suspects an inherited syndrome that’s associated with colorectal cancer. In this case, undergoing significant testing should be considered. Risk factors to any family member may include a member who has colorectal cancer, has a history of polyps, cancer in the abdomen, or has a history of inflammatory bowel disease.

Risks are more significant if the family with colorectal cancer is diagnosed before the age of 45. Genetic testing to assess the potential growth of this cancer includes taking a sample of the hair, blood, or other bodily fluids that can be analyzed for DNA mutations linked to cancer or any genetic syndrome.

Some potential syndromes you may inherit from a first-degree family includes:

• Familial Colorectal Cancer – Increased risks of developing colorectal cancer at some point in their life but most commonly at an early age.
• Peutz-Jeghers Syndrome (PJS) – Results in increased risks to colorectal cancer and other cancers in the breast, pancreas, and ovaries.