The staging system most often used for colorectal cancer is the American Joint Committee on Cancer (AJCC) TNM system, which is based on 3 key pieces of information:

• The extent (size) of the tumor (T): How far has the cancer grown into the wall of the colon or rectum? These layers, from the inner to the outer, include:
  • The inner lining (mucosa), which is the layer in which nearly all colorectal cancers start. This includes a thin muscle layer (muscularis mucosa).
  • The fibrous tissue beneath this muscle layer (submucosa)
  • A thick muscle layer (muscularis propria)
  • The thin, outermost layers of connective tissue (subserosa and serosa) that cover most of the colon but not the rectum
  • The spread to nearby lymph nodes (N): Has the cancer spread to nearby lymph nodes?
  • The spread (metastasis) to distant sites (M): Has the cancer spread to distant lymph nodes or distant organs such as the liver or lungs?The system described below is the most recent AJCC system effective January 2018. It uses the pathologic stage (also called the surgical stage) which is determined by examining tissue removed during an operation. This is also known as surgical staging. This is likely to be more accurate than clinical staging, which takes into account the results of a physical exam, biopsies, and imaging tests, done before surgery.

    Numbers or letters after T, N, and M provide more details about each of these factors. Higher numbers mean the cancer is more advanced.”

American Cancer Society (https://www.cancer.org/cancer/colon-rectal-cancer/detection-diagnosis-staging/staged.html)

“Colorectal cancer is the 2nd most deadliest cancer. One in 24 are at risk for colonrectal cancer; get educated and get screened.  If you were born the 1990’s you have 2x the risk factor for colon cancer and 4x the risk factor for rectal cancer than those born in 1950’s.  The symptoms of colonrectal cancer can be asymptomatic.”

Colon Cancer Coalition (https://coloncancercoalition.org/get-educated/what-you-need-to-know/colon-cancer-facts/)

Signs and symptoms of colon cancer include:

• A change in your bowel habits, including diarrhea or constipation or a change in the consistency of your stool, that lasts longer than four weeks
• Rectal bleeding or blood in your stool
• Persistent abdominal discomfort, such as cramps, gas or pain
• A feeling that your bowel doesn’t empty completely
• Weakness or fatigue
• Unexplained weight loss

Many people with colon cancer experience no symptoms in the early stages of the disease. When symptoms appear, they’ll likely vary, depending on the cancer’s size and location in your large intestine.

Diagnosis

Screening for colon cancer

Doctors recommend certain screening tests for healthy people with no signs or symptoms in order to look for early colon cancer. Finding colon cancer at its earliest stage provides the greatest chance for a cure. Screening has been shown to reduce your risk of dying of colon cancer.

Several screening options exist — each with its own benefits and drawbacks. Talk about your options with your doctor, and together you can decide which tests are appropriate for you. If a colonoscopy is used for screening, polyps can be removed during the procedure before they turn into cancer.

Diagnosing colon cancer

• Using a scope to examine the inside of your colon. Colonoscopy uses a long, flexible and slender tube attached to a video camera and monitor to view your entire colon and rectum. If any suspicious areas are found, your doctor can pass surgical tools through the tube to take tissue samples (biopsies) for analysis and remove polyps.
• Blood tests. No blood test can tell you if you have colon cancer. But your doctor may test your blood for clues about your overall health, such as kidney and liver function tests.Your doctor may also test your blood for a chemical sometimes produced by colon cancers (carcinoembryonic antigen or CEA). Tracked over time, the level of CEA in your blood may help your doctor understand your prognosis and whether your cancer is responding to treatment.

“Memorial Sloan Kettering Cancer Center recommends these healthy habits, which may lower your risk of colon cancer:

• Eat more fruits, vegetables, and fiber, and less animal and fat. The American Cancer Society recommends that you eat at least five servings of fruits and vegetables each day. Choosing such foods as beans and whole-grain bread, cereal, grain, rice, and pasta is a great way to improve your diet. Foods rich in calcium and folic acid (such as legumes, citrus, and broccoli) may also reduce your risk of colon cancer.
• Exercise regularly. Even moderate regular physical activity — such as taking the stairs instead of the elevator, raking leaves, or walking — can help reduce your risk of colon cancer.
• Maintain a healthy weight. Obesity is an important risk factor for colon cancer.”

Memorial Sloan Kettering Cancer Center (https://www.mskcc.org/cancer-care/types/colon/prevention-risk#how-can-i-lower-my-risk-of-colon-cancer-)

How does colon-recto cancer even start:

Most colorectal cancers start as a growth on the inner lining of the colon or rectum. These growths are called polyps.

Some types of polyps can change into cancer over time (usually many years), but not all polyps become cancer. The chance of a polyp turning into cancer depends on the type of polyp it is. There are different types of polyps.

• Adenomatous polyps (adenomas): These polyps sometimes change into cancer. Because of this, adenomas are called a pre-cancerous condition. The 3 types of adenomas are tubular, villous, and tubulovillous.
• Hyperplastic polyps and inflammatory polyps: These polyps are more common, but in general they are not pre-cancerous. Some people with large (more than 1cm) hyperplastic polyps might need colorectal cancer screening with colonoscopy more often.
• Sessile serrated polyps (SSP) and traditional serrated adenomas (TSA): These polyps are often treated like adenomas because they have a higher risk of colorectal cancer.

Other factors that can make a polyp more likely to contain cancer or increase someone’s risk of developing colorectal cancer include:

• If a polyp larger than 1 cm is found
• If more than 3 polyps are found
• If dysplasia is seen in the polyp after it’s removed. Dysplasia is another pre-cancerous condition. It means there’s an area in a polyp or in the lining of the colon or rectum where the cells look abnormal, but they haven’t become cancer.

The body is made up of trillions of living cells. Normal body cells grow, divide into new cells, and die in an orderly way. During the early years of a person’s life, while they are still growing, their normal cells divide faster. Once the person becomes an adult, most cells divide only to replace worn-out or dying cells or to repair injuries.

Cancer begins when cells in a part of the body start to grow out of control. There are many kinds of cancer, but they all start because of out-of-control growth of abnormal cells.

Cancer cell growth is different from normal cell growth. Instead of dying, cancer cells continue to grow and form new, abnormal cells. In most cases the cancer cells form a tumor. Cancer cells can also invade (grow into) other tissues, something that normal cells cannot do. Growing out of control and invading other tissues are what makes a cell a cancer cell.

Cells become cancer cells because of damage to DNA. DNA is in every cell and directs all its actions. In a normal cell, when DNA is damaged the cell either repairs the damage or the cell dies. In cancer cells, the damaged DNA is not repaired, but the cell doesn’t die like it should. Instead, this cell goes on making new cells that the body does not need. These new cells will all have the same damaged DNA as the first abnormal cell does.

People can inherit damaged DNA, but most often the DNA damage is caused by mistakes that happen while the normal cell is reproducing or by something in our environment. Sometimes the cause of the DNA damage is something obvious, like cigarette smoking. But often no clear cause is found.

Cancer cells often travel to other parts of the body, where they begin to grow and form new tumors that replace normal tissue. This process is called metastasis. It happens when the cancer cells get into the bloodstream or lymph vessels of our body.

No matter where a cancer may spread, it is always named for the place where it started. For example, breast cancer that has spread to the liver is still called breast cancer, not liver cancer

Different types of cancer can behave very differently. For example, lung cancer and breast cancer are very different diseases. They grow at different rates and respond to different treatments. This is why people with cancer need treatment that is aimed at their particular kind of cancer.

Not all tumors are cancerous. Tumors that aren’t cancer are called benign. Benign tumors can cause problems – they can grow very large and press on healthy organs and tissues. But they cannot grow into (invade) other tissues. Because they can’t invade, they also can’t spread to other parts of the body (metastasize). These tumors are rarely life threatening.

Their are risk factors in getting colon cancer as well as other cancer and noncancerous diseases BUT remember their are modifiable risk factors leading to disease which are factors we can’t control being 4 areas 1.)Race 2.)Age 3.) Sex 4.) Heredity in the family (particularly nuclear and grandparents meaning higher risk than a first cousin or second cousin and down the family tree).

Risk Factors to colon cancer can be:

Most colorectal cancers occur in people without a family history of colorectal cancer. Still, as many as 1 in 5 people who develop colorectal cancer have other family members who have been affected by this disease.  People with a history of colorectal cancer in one or more first-degree relatives (parents, siblings, or children) are at increased risk. The risk is about doubled in those with only one affected first-degree relative=Nuclear Family. It is even higher if that relative was diagnosed with cancer when they were younger than 45, or if more than one first-degree relative is affected.

The reasons for the increased risk are not clear in all cases. Cancers can “run in the family” because of inherited genes, shared environmental factors, or some combination of these.

Having family members who have had adenomatous polyps is also linked to a higher risk of colon cancer. (Adenomatous polyps are the kind of polyps that can become cancerous.)

1-Inherited syndromes

About 5% to 10% of people who develop colorectal cancer have inherited gene defects (mutations) that can cause family cancer syndromes and lead to them getting the disease. These syndromes often lead to cancer that occurs at a younger age than is usual.

The most common inherited syndromes linked with colorectal cancers are familial adenomatous polyposis (FAP) and hereditary non-polyposis colorectal cancer (HNPCC), but other rarer syndromes can also increase colorectal cancer risk.

Familial adenomatous polyposis (FAP): FAP is caused by changes (mutations) in the APC gene that a person inherits from his or her parents. About 1% of all colorectal cancers are due to FAP.

The most common type of FAP causes people to develop hundreds or thousands of polyps in their colon and rectum, usually in their teens or early adulthood.

Hereditary non-polyposis colon cancer (HNPCC): HNPCC, also known as Lynch syndrome, accounts for about 2% to 4% of all colorectal cancers.

The cancers in this syndrome also develop when people are relatively young, although not as young as in FAP. People with HNPCC may also have polyps, but they only have a few, not hundreds as in FAP. The lifetime risk of colorectal cancer in people with this condition may be as high as 80%.

Turcot syndrome: This is a rare inherited condition in which people are at increased risk of adenomatous polyps and colorectal cancer, as well as brain tumors. There are actually 2 types of Turcot syndrome:

• One can be caused by gene changes similar to those seen in FAP, in which cases the brain tumors are medulloblastomas.
• The other can also be caused by gene changes similar to those seen in HNPCC, in which cases the brain tumors are glioblastomas.
• MUTYH-associated polyposis:Racial and ethnic background  1. Jews of Eastern European descent (Ashkenazi Jews) have one of the highest colorectal cancer risks of any ethnic group in the world. Several gene mutations leading to an increased risk of colorectal cancer have been found in this group. People with type 2 (usually non-insulin dependent) diabetes have an increased risk of developing colorectal cancer. Both type 2 diabetes and colorectal cancer share some of the same risk factors (such as excess weight). But even after taking these factors into account, people with type 2 diabetes still have an increased risk. They also tend to have a less favorable prognosis (outlook) after diagnosis.  

2-Night shift workers are prone to cancers (colon/rectal and breast cancer).

3-Previous treatment for certain cancers –

Several studies have suggested that men who had radiation therapy to treat prostate cancer might have a higher risk of rectal cancer because the rectum receives some radiation during treatment. Men should consider the many possible side effects of prostate cancer treatment when making treatment decisions. Some doctors recommend that the risk of rectal cancer should be considered as one of those possible side effects but the patient is always responsible in doing research on their own before making the final decisions of treatment.  They choose the treatment they feel is the best choice; not the doctor.

• Some studies have found that men who survive testicular cancer seem to have a higher rate of colorectal cancer and some other cancers. This might be because of the treatments they have received.

4-Factors less clear but can effect risk for colon cancer:

        1-Type 2 diabetes

       2-Racial Group African Americans have the highest colorectal cancer incidence and mortality rates of all       racial groups in the United States. The reasons for this are not yet understood.

        3-Peutz-Jeghers syndrome: People with this rare inherited condition tend to have freckles around the mout (and sometimes on the hands and feet) and a special type of polyp in their digestive tracts (called hamartoma). They are at greatly increased risk for colorectal cancer, as well as several other cancers, which usually appear at a younger than normal age. This syndrome is caused by mutations in the gene STK1.  People with this syndrome develop colon polyps which will become cancerous if the colon is not removed.

Patients undergo lifelong surveillance of organs to monitor for cancer and prevent secondary problems from the polyps.

REVISED 3/05/2023

“A risk factor is anything that raises your chance of getting a disease such as cancer. Different cancers have different risk factors. Some risk factors, like smoking, can be changed. Others, like a person’s age or family history, can’t be changed.

But having a risk factor, or even many, does not mean that you will get the disease. And some people who get the disease may not have any known risk factors.

Researchers have found several risk factors that might increase a person’s chance of developing colorectal polyps or colorectal cancer.”

American Cancer Society (https://www.cancer.org/cancer/colon-rectal-cancer/causes-risks-prevention/risk-factors.html)

The colon is part of the body’s digestive system. The digestive system removes and processes nutrients (vitamins, minerals, carbohydrates, fats, proteins, and water) from foods and helps pass waste material out of the body. The digestive system is made up of the esophagus, stomach, and the small and large intestines. The colon (large bowel) is the first part of the large intestine and is about 5 feet long. Together, the rectum and anal canal make up the last part of the large intestine and are about 6-8 inches long. The anal canal ends at the anus (the opening of the large intestine to the outside of the body).

Colorectal cancer starts in the colon or the rectum. These cancers can also be called colon cancer or rectal cancer, depending on where they start. Colon cancer and rectal cancer are often grouped together because they have many features in common.  So this is why pt’s are diagnosed at times colorectal cancer by some M.D.’s.

Key Points

“Regular screening, beginning at age 45, is the key to preventing colorectal cancer (cancer of the colon or rectum). If you’re 45 to 75 years old, get screened for colorectal cancer regularly. If you’re younger than 45 and think you may be at high risk of getting colorectal cancer, or if you’re older than 75, talk to your doctor about screening.

Colorectal polyps and colorectal cancer don’t always cause symptoms, especially at first. That is why getting screened regularly for colorectal cancer is so important.”

Centers for Disease Control and Prevention-CDC (https://www.cdc.gov/cancer/dcpc/resources/features/colorectalawareness/index.htm)

“The large intestine is the last part of the gastrointestinal (GI) tract, the long, tube-like pathway that food travels through your digestive system. The large intestine is about six feet long — much shorter than the small intestine, which is 22 feet. It’s called the large intestine because it’s wider — about three inches, while the small intestine is only one inch in diameter. It follows from the small intestine and ends at the anal canal, where food waste leaves your body. The large intestine, also called the large bowel, is where food waste is formed into poop, stored, and finally excreted. It includes the colon, rectum and anus. Sometimes “colon” is also used to describe the entire large intestine.”

Cleveland Clinic (https://my.clevelandclinic.org/health/body/22134-colon-large-intestine)

the colon to rectum

The GI tract starts at the mouth, to the esophagus, to the stomach, to the small intestines, than to the large intestines, than the rectum to the anus where we remove stool from the GI tract.

Know the cecum is a pouch-like passage that connects the colon to the ileum (the last part of the small intestine). If cancer develops in the cecum, it is treated like colon cancer.

The entire colon is about 5 feet (150 cm) long, and is divided into five major segments. The rectum is the last anatomic segment before the anus, the last part of the GI tract is where the bowel movement comes out.

The ascending and descending colon are supported by peritoneal folds called mesentery.

The proximal colon is the ascending colon and the transverse colon together. The distal colon is the descending colon and the sigmoid colon together.

The right colon consists of the cecum, ascending colon, hepatic flexure and the right half of the transverse colon. The left colon consists of the left half of the transverse colon, splenic flexure, descending colon, and sigmoid.

The intestine is part of the digestive system.  It is made up of the small intestine and the large intestine. The colon and rectum are parts of the large intestine. The colon is a U-shaped tube made of muscle, found below the stomach. The rectum is a shorter tube connected to the colon. Together, the colon and rectum are about 2 metres (6.5 feet) long. They are surrounded by other organs including the spleen, liver, pancreas, bladder and reproductive organs.

The large intestine is made up of the cecum, colon, rectum and anus. The colon and rectum are held in the abdomen by folds of tissue called mesenteries.

The rectum is the lower part of the large intestine that connects to the sigmoid colon. It is about 15 cm (6 in) long. It receives waste from the colon and stores it until it passes out of the body through the anus.

The anus is the opening at the lower end of the rectum through which stool is passed from the body.

The key functions of the colon include the following:

• Water and nutrient absorption
• Vitamin absorption
• Feces compaction
• Potassium and chloride secretion
• Moving waste material toward the rectum

Mechanism

Motility

The intestinal wall is made up of multiple layers. The 4 layers of the large intestine from the lumen outward are the mucosa, submucosa, muscular layer, and serosa. The muscular layer is made up of 2 layers of smooth muscle, the inner, circular layer, and the outer, longitudinal layer. These layers contribute to the motility of the large intestine. There are 2 types of motility present in the colon, haustral contraction and mass movement. Haustra are saccules in the colon that give it its segmented appearance. Haustral contraction is activated by the presence of chyme and serves to move food slowly to the next haustra, along with mixing the chyme to help with water absorption. Mass movements are stronger and serve to move the chyme to the rectum quickly.

Absorption of Water and Electrolytes

Absorption of water occurs by osmosis. Water diffuses in response to an osmotic gradient established by the absorption of electrolytes. Sodium is actively absorbed in the colon by sodium channels. Potassium is either absorbed or secreted depending on the concentration in the lumen. The electrochemical gradient created by the active absorption of sodium allows for this. Chloride ions are exchanged for bicarbonate ions across an electrochemical gradient.

Production/Absorption of Vitamins

The colon also plays a role in providing required vitamins through an environment that is conducive for bacterial cultivation. The colon houses trillions of bacteria that protect our gut and produce vitamins. The bacteria in the colon produce substantial amounts of vitamins by fermentation. Vitamin K and B vitamins, including biotin, are produced by the colonic bacteria. These vitamins are then absorbed into the blood. When dietary intake of these vitamins is low in an individual, the colon plays a significant role in minimizing vitamin disparity.

Now that we have reviewed the colon and rectum anatomy and physiology we will tomorrow start on colon cancer awareness for March.

Know cancer in the anal canal or anus is treated differently from colorectal cancer.