Colon Cancer

Unfortunately, many of the subjects I choose to write about in Medicana are driven by the diagnosis of someone I know with the condition in question.

In the case of colon cancer, I am sorry to report that a friend of mine was just diagnosed with it. I don't yet know all the details, but her symptoms led to an initial diagnosis of some type of ovarian tumor, based on an ultrasound and an MRI. Once surgery was performed, it was discovered the tumor was actually colon cancer that had spread to the ovaries - not a good scenario.

I do not yet know the staging of her cancer since all the tests have not come back yet, but I thought I'd do the research on colon cancer now so there would be plenty of information available once she finds out more.

I am posting this information in hopes that my research may help discover new treatments or information that may help her and her family as they work with her doctors to find the right treatment for her cancer, and help anyone else who may have been diagnosed with this disease.

Colon Cancer - What is it?

Colon cancer, more generally known as colorectal cancer, is any cancer affecting the colon or rectum. The colon is the large intestine and the rectum the last six inches of the large intestine.

Colon cancer usually begins as small, noncancerous clump of cells called adenomatous polyps. Eventually these polyps can become colon cancers.

Because polyps usually cause few symptoms, or in many cases, no symptoms at all, it is important for people to get screened for colon cancer once they reach middle age; usually 50, unless there are risk factors in the family, in which case screening should start earlier.

There are three types of polyps:

- Adenomas: These are likely to turn into cancer.
- Hyperplastic polyps: These rarely turn into cancer.
- Inflammatory polyps: These can follow a flare-up of ulcerative colitis, and can turn cancerous, which is why ulcerative colitis is a risk factor for colon cancer.

Most colon cancers are adenocarcinomas (cancers that begin in cells that make and release mucus and other fluids).

What Are the Symptoms of Colon Cancer?

Often there are no symptoms that show up for colon cancer in its early stages. The symptoms to watch out for are:

- Any change in bowel habits, including diarrhea or constipation or a change in the consistency of your stool that lasts more than a week or two. Narrowing of the stool is another symptom.
- Rectal bleeding or blood in your stool
- Persistent abdominal discomfort, such as cramps, gas or pain
- Abdominal pain with a bowel movement
- A feeling that your bowel doesn't empty completely, or feeling full or bloated
- Unexplained anemia
- Weakness or fatigue
- Unexplained weight loss

According to Medicinenet.com (link below), colon cancer may be present for several years before symptoms develop. Symptoms vary according to where in the large bowel the tumor is located. The right colon has plenty of room, and cancers of the right colon can grow to large sizes before they cause any symptoms. Usually right-sided cancers cause anemia due to the slow loss of blood over a long period of time, which can lead to fatigue, weakness and shortness of breath. Because the left colon is narrower than the right colon, cancers of the left colon are more apt to cause partial or complete bowel obstruction.

What Are the Causes and Risk Factors for Colon Cancer?

There are a number of factors that put a person at higher risk for colon cancer:

Age: About 90 percent of people diagnosed with colon cancer are older than 50. Only about 10% of colon cancer cases occur in younger people.

A personal history of colorectal cancer or polyps: Naturally it makes sense that if a person has already had colon cancer they would have a risk of colon cancer again in the future. However, people who have had a history of adenomatous polyps also have a higher likelihood of getting colon cancer and will need regular screening.

Inflammatory bowel disease/conditions: Chronic conditions such as ulcerative colitis and Crohn's disease can increase the risk of colon cancer.

Genetics: Inherited syndromes passed through the family can increase the risk of colon cancer. Inherited conditions account for only about 5 percent of all colon cancers.

One such genetic condition is called familial adenomatous polyposis (FAP), which is a rare disorder that causes thousands of polyps to develop in the lining of the colon and rectum. People with untreated FAP have >90% chance of developing colon cancer by age 45.

Hereditary nonpolyposis colorectal cancer (HNPCC), which is also called Lynch syndrome, is more common than FAP. Sufferers of Lynch syndrome also tend to develop colon cancer at an early age. Both FAP and HNPCC can be detected through genetic testing.

Certain HNPCC patients are also at risk of developing uterine cancer, stomach cancer, ovarian cancer, and cancers of the ureters (the tubes that connect the kidneys to the bladder), and the biliary tract (the ducts that drain bile from the liver to the intestines).

MYH polyposis syndrome is another, recently discovered, hereditary colon cancer syndrome. Affected people tend to develop 10-100 polyps starting at around 40 years of age, and are at high risk of developing colon cancer.

According to Medicinenet.com, "Among first-degree relatives of colon cancer patients, the lifetime risk of developing colon cancer is 18% (a threefold increase over the general population in the United States).

Even though family history of colon cancer is an important risk factor, majority (80%) of colon cancers occur sporadically in patients with no family history of colon cancer. Approximately 20% of cancers are associated with a family history of colon cancer. And 5 % of colon cancers are due to hereditary colon cancer syndromes. Hereditary colon cancer syndromes are disorders where affected family members have inherited cancer-causing genetic defects from one or both of the parents."

Family history of colon cancer and colon polyps: If a person has a parent, brother or sister or a child with colon cancer, this too is a risk factor. This may be a hereditary connection or it might be due to mutual exposure to an environmental toxin, diet or lifestyle that leads to the condition.

Diet: Colon cancer and rectal cancer may be associated with a diet low in fiber and high in fat and calories. It is believed that the breakdown products of fat metabolism lead to the formation of cancer-causing chemicals. Some studies have found an increased risk of colon cancer in people who eat diets high in red meat and processed meats. Lack of fruits and vegetables may be part of the picture, since increased consumption of these foods seems to have a protective effect against colon cancer.

Lack of exercise: If a person is inactive, they are more likely to develop colon cancer, possibly by causing waste to stay in the colon longer.

Diabetes: People with diabetes and insulin resistance may have an increased risk of colon cancer. Just one more reason to try to avoid diabetes; it seems to be implicated in so many other diseases.

Obesity: People who are obese have an increased risk of colon cancer and an increased risk of dying of colon cancer when compared with people considered normal weight. Of course, obesity also may be associated with a high fat diet, sedentary lifestyle, and diabetes, so it may all be connected.

Smoking: People who smoke cigarettes may have an increased risk of getting colon cancer - and of dying of it.

Heavy Use of Alcohol: Heavy drinking may increase the risk of colon cancer.

Growth hormone disorder: Acromegaly, an uncommon disorder that causes an excess of growth hormone in the body, may increase the risk of colon polyps and colon cancer. (Sounds to me as if the use of human growth hormone by sports figures might not be a good idea).

Previous radiation therapy for cancer: Radiation therapy directed at the abdomen to treat previous cancers may increase the risk of colon cancer.

How Is It Diagnosed?

There are a number of screening methodologies available to find colon cancer before it is advanced enough to cause symptoms - and at a stage where it is most curable.

Unfortunately, none of them are very appealing to people, which is why many people avoid the whole subject. This is tragic, since when caught early, colon cancer is very curable. In fact, some of the screening methods actually prevent it from developing in the first place by removing polyps before they have a chance to go bad.

The following are the screening techniques currently used to detect colon cancer:

- Fecal occult blood test: This is a fancy way of saying it's a test to detect hidden (occult) blood in the stool. It can be done in the doctor's office, or by using a kit at home. If blood is detected, the doctor would then order more tests to find out the cause. Blood in the stool does not always mean cancer; it can be caused by a polyp that has not yet become cancerous, certain foods or medications (such as aspirin), or hemmorrhoids. A negative test for occult blood is not a guarantee of no cancer, either: Not all cancers bleed, and some only bleed occasionally, so they can be missed. This test, however, is least invasive and more apt to be performed willingly by the patient. A digital rectal exam may also be performed to check for growths or blood in the lower part of the rectum.

- Flexible Sigmoidoscopy: For this test, the lower colon must be cleaned out ahead of time, usually through an enema; the sigmoidoscopy is usually done in the doctor's office, where the doctor examines the last two feet (1/3) of the colon for polyps or other anomalies, using a slender, flexible lighted tube. The colon is inflated with air to enable the doctor to examine the colon. The drawback to this test is that since it only examines part of the colon, polyps or growths farther up will not be detected. I had one of these once after I'd noticed blood in my stool (it turned out to be hemmorrhoids).

- Barium Enema: In this test, barium is inserted into the cleaned colon, with or without air added. Barium is a contrast dye that enables the doctor to see irregularities along the colon walls through X-ray examination. Sometimes a flexible sigmoidoscopy is done as well. The barium enema is not able to identify small cancers and small polyps. A colonoscopy is usually recommended if suspicious lesions are sighted in the barium enema test, since no sampling is possible during this test.

- Colonoscopy: The gold standard of colon cancer screening, the colonoscopy enables the physician to examine the full length of the colon with a flexible lighted tube, similar to the one used in sigmoidoscopy, with a video camera and monitor attached. The colon must be thoroughly cleaned out ahead of time; the patient must consume a laxative solution the night before. The beauty of the colonoscopy is that the doctor is able to remove polyps or other suspicious growths with the colonoscope, and find out whether they are cancerous. As mentioned previously, removal of the polyps can actually prevent cancer since they will no longer have the opportunity to develop into cancer once they are removed. Patients are under sedation during this procedure so there is no discomfort; most people do not remember the experience due to new medications that are used. If nothing suspicious is found during the colonoscopy, patients are advised to have another one in 7-10 years.

I had a colonoscopy at age 47, since both of my parents have had polyps. I didn't feel a thing and felt fine afterwards. I am due for another this year and you can be sure I'm going to get it.

- Virtual Colonoscopy: Although many insurance companies do not yet cover this method, it is becoming more popular since it is not invasive. The patient cleans the colon ahead of time, similar to preparation for the standard colonoscopy, but instead the procedure is a simple computerized tomography (CT) scan. There is no sedation, no recovery needed; and no risk of perforating the colon. However, the colon does need to be filled with air, which is uncomfortable. Virtual colonoscopy is not as good as the real thing in finding very small polyps or flat lesions on the wall of the colon. In addition,if anything is seen on the scan, the patient would still need a standard colonoscopy to follow up, since there is no way to sample anything suspicious that is seen.

All of the invasive methods carry some risk of perforating the colon; however, the benefits of screening far outweigh the risks.

If a person presents to the doctor with actual symptoms, rather than just needing a routine screening, usually a colonoscopy would be ordered so as to enable the physician to take biopsies of anything that is found. When it is less clear that the symptoms are colon-related, MRIs, CT scans or ultrasounds may be ordered first.

If cancer is diagnosed, the next step is staging. The first step may be to have a CT scan of the abdomen and a chest X-ray to make sure nothing has spread yet.

How Is Colon Cancer Treated?

Surgery is the first line of treatment for colon cancer. It is important to remove as much of the cancer as possible, and also to remove lymph nodes in the abdomen to help stage the cancer and prevent it from spreading.

Depending on how much of the colon is affected, the patient may need to have more or less of it removed. In some cases the entire colon has to be removed; in others, just a section - and in some cases, only the cancerous polyp needs to be taken out.

During surgery, the tumor, a small piece of the surrounding healthy colon, and adjacent lymph nodes are removed. The surgeon then reconnects the healthy sections of the bowel. Recent studies have indicated that the more lymph nodes removed at the time of surgery, the better the prognosis.

If the cancer is in the right or left side of the colon but above the rectum, usually a resection of the colon will work. If the rectum or anal sphincter is involved, it may be necessary for the patient to have a colostomy bag; he or she can no longer defecate and stool goes into the bag instead.

According to EMedicineHealth.com, in the case of early cancers, sometimes there is no further treatment, just follow-up:

"Once your cancerous colon has been removed and you receive any other treatment recommended by your cancer care team, you will see your gastroenterologist or cancer specialist (oncologist) regularly for follow-up visits. These visits will allow your team to see if the cancer has spread and to detect newly formed cancers.

These follow-up visits should include, at minimum, the following:

Colonoscopy within 3 months after your surgery.
Colonoscopy 1 year after surgery and every 3 years after that.
Test for occult (hidden) blood in your stool every year, followed by colonoscopy if the test result is positive.

A screening tool—measurement of carcinoembryonic antigen (CEA) level—is available to test for cancer recurrence following cancer surgery.

CEA is a protein normally found in trace amounts in your bloodstream but is present in increased amounts in people with colon cancer. It is referred to as a tumor marker.

Blood CEA levels should be measured before colon cancer surgery and then at intervals of 2-3 months.

Increasing levels of serum CEA may indicate that colon cancer has come back and that you should seek further evaluation.

Once you have had several blood tests with negative results, you probably don't need to continue the tests indefinitely. However, no one is sure how long you should continue to have the tests."

Colon cancer, as mentioned before, is staged based on how much it has spread. If it is not caught early, further treatment is needed.

What Are the Stages of Colon Cancer?

There are a number of ways to stage colon cancer; there is a simple Stage I-IV method, but the more complex way to stage cancer is to divide up the various aspects of it into the tumor itself, the lymph node involvement, and whether or not it has spread (metastasized). From the Oncology Channel (link below), here is the breakout of these details:

"TNM Staging System (Tumor, Node, Metastasis)

Tumor
T1: Tumor invades submucosa.
T2: Tumor invades muscularis propria.
T3: Tumor invades through the muscularis propria into the subserosa, or into the pericolic or perirectal tissues.

(NOTE: these are all fancy words for the various layers of the intestinal wall).

T4: Tumor directly invades other organs or structures, and/or perforates.

Node

N0: No regional lymph node metastasis.
N1: Metastasis in 1 to 3 regional lymph nodes.
N2: Metastasis in 4 or more regional lymph nodes.

Metastasis

M0: No distant metastasis.
M1 Distant metastasis present.

Stage Groupings

Stage I: T1 N0 M0; T2 N0 M0
Cancer has begun to spread, but is still in the inner lining.

Stage II: T3 N0 M0; T4 N0 M0
Cancer has spread to other organs near the colon or rectum. It has not reached lymph nodes.

Stage III: any T, N1-2, M0
Cancer has spread to lymph nodes, but has not been carried to distant parts of the body.

Stage IV: any T, any N, M1
Cancer has been carried through the lymph system to distant parts of the body. This is known as metastasis. The most likely organs to experience metastasis from colorectal cancer are the lungs and liver."

Treatment may include chemotherapy, radiation, or both. According to Oncology Channel, the following regimens are frequently used:

"Chemotherapy is often used as a first-line treatment for metastatic colorectal cancer to destroy cancer cells that have metastasized (spread). It also may be used prior to surgery (called neoadjuvant therapy) to shrink the tumor, may be administered following surgery (called adjuvant therapy), and may be combined with biological therapy (also called immunotherapy) and radiation therapy.

Newer combinations of chemotherapy drugs, such as FOLFOX (5-fluorouracil [5-FU], leucovorin, and oxaliplatin [Eloxatin®]) and FOFIRI (5-fluorouracil [5-FU], leucovorin, and irinotecan [Camptosar®]) may be used to prevent recurrence following surgery or to shrink the tumor prior to surgery.

A combination of chemotherapy drugs (5-fluorouracil [5-FU], leucovorin, and irinotecan [CPT11]), administered intravenously, is standard treatment for metastatic colorectal cancer. Side effects include diarrhea, mouth irritation (mucositis), low white blood cell count (e.g., neutropenia), and hair loss (alopecia).

Colorectal cancer with liver metastasis also may be treated using floxuridine (FUDR®) administered intra-arterially (i.e., through an artery). Side effects include nausea, vomiting, diarrhea, and inflammation of the intestine (enteritis).

In addition to chemotherapy drugs, blocking agents (e.g., cetuximab [Erbitux®]) may also be used to treat metastatic colorectal cancer. These drugs prevent cancer cell receptors from receiving factors (e.g., epidermal growth factor) that cause cell growth, cell division, and additional metastasis. Blocking agents target specific cells so they usually do not cause systemic side effects. Side effects of these drugs include allergic reactions (e.g., difficulty breathing, hives, low blood pressure, rash).

Bevacizumab (Avastin®) may also be used to treat advanced colorectal cancer. This medication prevents new blood vessels, which are necessary for tumor growth, from forming. It does not affect normal tissues that already have an established blood supply. Side effects include blood clots and high blood pressure, which can be controlled with medication.

(NOTE: Avastin is one of a new class of drugs called angiogenesis inhibitors and they have shown to be quite effective against colon cancer.)

Panitumumab (Vectibix™) is the first entirely human monoclonal antibody approved by the Food and Drug Administration (FDA) to treat patients with metastatic colorectal cancer following chemotherapy. This medication is administered intravenously once every 2 weeks.

Immunotherapy

Immunotherapy, or biological therapy, attempts to stimulate the immune system to fight disease and protect the body from side effects of chemotherapy. Immunotherapy agents that may be used to treat colorectal cancer include bacilli Calmette-Guerin (BCG) and levamisole (Ergamisol®).

Immunotherapy may cause flu-like side effects such as the following:

Chills
Diarrhea
Fever
Loss of appetite
Muscle aches and weakness
Nausea and vomiting

Radiation Therapy

Radiation therapy uses high energy x-rays to destroy cancer cells and shrink tumors. External beam radiation (i.e., radiation from a machine outside the body) may be used in addition to surgery to treat colorectal cancer (called adjuvant therapy). It also may be used to relieve symptoms (called palliative treatment) in patients with metastatic colorectal cancer.

Side effects include fatigue, hair loss, reddened skin, and swelling (edema). Medicines and other treatments can reduce the intensity of the side effects. As with other cancer treatments, the incidence of side effects varies with patient health and the exact nature of the treatment.

Follow-up Treatment

Follow-up care is recommended for colorectal cancer patients to ensure that recurrent or metastatic disease is detected as soon as possible. Patients should undergo regular physical examinations, fecal occult blood tests, colonoscopies, CT scans, and chest x-rays.

Prognosis

Prognosis depends on the stage of the disease and the overall health of the patient. Overall, colorectal cancer patients have a 5-year survival rate of about 61%. The 5-year survival rate is about 92% when the disease is treated before it has spread (metastasized); 64% when the cancer has spread to nearby organs or lymph nodes; and 7% when it has spread to other parts of the body (e.g., liver, lungs)."

Depending on the severity of the disease, some patients may want to try to get into clinical trials. If you have been diagnosed with advanced colon cancer and you are located near a major cancer center, it is possible trials are being held of treatments that are not yet generally available to patients that may be more effective than current methods.

Clinical trials can be found on-line in a number of places. Please see below for some links.

http://bethesdatrials.cancer.gov/colorectal/index.aspx
http://www.mdanderson.org/patients_public/clinical_trials/?Referrer=Google&KW=Cancer_Research&gclid=CObv_IKH4ZACFShsGgodSzLZYA
http://www.fightcolorectalcancer.org/patients/clinicaltrials/index.htm
http://www.mskcc.org/mskcc/html/14075.cfm
http://www.ccalliance.org/patient/clinical/clinical.html
http://clinicaltrials.gov/ct/search?term=colon+cancer
http://www.mayoclinic.org/colon-cancer/clintrials.html
http://www.nlm.nih.gov/medlineplus/colorectalcancer.html#cat27

Be sure to check out the trials available before starting any treatment; always get a second opinion on your treatment before committing to something. For one thing, clinical trials don't always accept patients who have already had other treatments first.

Please note, although these trials are usually "double blind" trials (that is, patients and physicians don't know which patients are getting the experimental treatment), those who do not get the new treatment are given the current accepted treatment for the cancer, so no one gets a placebo.

Will You Get It?

You could, especially if you have any of the risk factors above. Colorectal cancer is the fourth most common cancer in the United States and the second leading cause of cancer death. A person at age 50 has about a 5 percent lifetime risk of being diagnosed with colorectal cancer and a 2.5 percent chance of dying from it.

Most people will not get it if they get screened at the recommended times. Unfortunately, people younger than 50 who have no other risk factors can get it too, and they are younger than the recommended age to start screening.

So any time you notice anything unusual about the way your body feels or how you feel overall, be sure to go to the doctor and get checked out.

And if you do find out you have cancer, always go to experts for your treatment. Get more than one opinion. Go to a major cancer center. I may sound like a broken record, but I'd rather be repetitive than not get the message across. Your life may depend upon it.

Sources:
http://www.medicinenet.com/colon_cancer/article.htm: Medicinenet.com
http://www.mayoclinic.com/health/colon-cancer/DS00035: The Mayo Clinic
http://www.cancer.gov/cancertopics/types/colon-and-rectal: Cancer.gov
http://www.emedicinehealth.com/colon_cancer/article_em.htm: EMedicineHealth.com
http://www.oncologychannel.com/coloncancer/staging.shtml: Oncology Channel
http://www.ahrq.gov/clinic/3rduspstf/colorectal/colorr.htm

For more information/treatments:
http://www.mdanderson.org/diseases/Colorectal/?gclid=CPKkh6fp4JACFRuhFQodBTLrXA: M.D. Anderson
http://www.mskcc.org/mskcc/html/5789.cfm: Memorial Sloan Kettering
http://www.nlm.nih.gov/medlineplus/ency/article/000262.htm: National Institutes of Health