Bowel cancer also known as colorectal cancer, is defined as a condition of the abnormal proliferation of cells in the colon, rectum, or vermiform appendix. Bowl is divided in 2 parts, the first part of the bowel, the small bowl, is involved with the digestion and absorption of food. The 2nd part, the large bowel which consist the the colon and rectum, is involved in absorption of water from the small bowel contents and broken down of certain materials in the feces into substances of which some of them to be re absorbed and reused by the body. Bowel cancer is relatively very common and slowly growing and progress cancer and in predictable way.
Bowel cancer is the third most commonly diagnosed cancer in developed countries, including U>S and Canada.
Types of bowel cancer
Most bowel cancers are adenocarcinomas, originated in epithelium tissues, including the surface layer of skin, glands and their tissues that line the cavities and organs of the body.
2. Squamous cell cancers
Squamous cells are the skin like cells that make up the bowel lining together with the gland cells. Squamous cell cancers are rare with the risk of 25 per 100000.
Other bowel tumours
Carcinoid is an unusual type of slow growth neuroendocrine tumor. It looks benign but might spread to other parts of the body as they grow in hormone producing tissue in the digestive system.
Leiomyosarcomas are the rare and resistant types of bowel cancer and generally not very responsive to chemotherapy or radiation. They are malignant abnormal mass of tissue of smooth muscles of colon, comprising between 5–10% of soft tissue sarcomas.
Bowel lymphomas are rare and more likely to start in the rectum rather in the colon. Many patients with lymphomas are diagnosed in the late stage and already spread to other organs.
Melanomas are rare malignant tumor of cells that produce the dark pigment. This type of bowel cancer usually originates from somewhere else and then spread to the bowel.
1. Changes in bowel habits
2. Narrow stools
5. Irritable bowel syndrome
7. Ulcerative colitis
8. Crohn's disease,
10. Peptic ulcer disease
11. Abdominal pain
12. Unintentional weight loss
13. Loss of appetite
14. Unexplained fatigue
15. Nausea or vomiting
Causes and Risk factors
The disease is more common in people over the age of 50 and increase with age. Regular colonoscopy after age of 50 is valuable to detect the disease in the early stage and decrease the risk of development of bowel cancer.
2. Bowl inflammatory diseases
Prolonged period of inflammatory diseases of the colon, such as Ulcerative Colitis and Crohn’s Disease, can increase your risk of colon cancer due to long term inflammation of the lining of the colon.
3. Family History of Bowel Cancer
If a patient's parents, siblings, children who has had colorectal cancer are more likely to develop bowel cancer.
4. Inherited Syndromes
Genetic syndromes passed through generations can increase the risk of developing colon cancer.
a. Familial adenomatous polyposis (FAP):
Familial adenomatous polyposis is an inherited condition in which numbers of benign polyp form mainly in the lining of the large intestine, but they can become malignant due to the mutations in the APC gene that a patient inherits from the parents.
b. Hereditary non-polyposis colon cancer (HNPCC)
HNPCC is also known as Lynch syndrome. It can increase the risk of developing bowel cancer than the general population due to mutation of genes in repairing DNA damage.
c. Turcot syndrome
Turcot syndrome is also a rare inherited condition in which cells become abnormal and form multiple adenomatous colon polyps anf eventually turn malignant.
d. Peutz-Jeghers syndrome
Peutz-Jeghers syndrome is an autosomal dominant genetic disease with condition of the development of benign hamartomatous polyps in the gastrointestinal tract and hyperpigmented macules on the lips and oral mucosa due to mutations in the gene STK1.
e. MUTYH-associated polyposis
MUTYH is a human gene encoding a DNA glycosylase. Mutations in the gene MUTYH increases the risk of develop colon polyps which eventually become cancerous if the colon is not removed.
5. Race and ethic background
a, African Americans have the highest risk of bowel cancer with unknown reasons (E. Mitchell, et al., 2009)
b. Ashkenazi Jews have a highest risk of development of bowel cancer due to several genes mutation (I. Shapira et al., 2002; DS. Weinberg et al., 2006)
6. Personal history of other cancer
Research shows that the risk of developing bowel cancer is increased for women with history of other cancer such as ovarian, uterine, endometrial or breast cancer.
Diet with high in animal and trans fat and less in fiber, vegetables and fruits is associated with high risk if bowel cancer. Cooking meats at very high temperatures such as frying, broiling or grilling create chemicals that increases the risk of bowel and other cancer.
8. Physical Inactivity
Researchers in Utah and northern California at the Kaiser Permanente Medical Care Program between 1997 and 2002 found that vigorous or moderated physical activity reduced the risk of bowel cancer in both men and women.
Abnormal glucose metabolism increases the risk of bowel cancer. Research from Cancer Research UK and the Medical Research Council studied 9600 participants. at the American Association for Cancer Research's Sixth Annual International Conference on Frontiers in Cancer Prevention Research found that women with diabetes are 1.5 times more likely to develop bowel cancer than women who don't have the metabolic disorder.
The George Institute for International Health in Sydney, Australia report showed that obese individuals (Body Mass Index* (BMI) >30 kg/m2) have a 20% greater risk of developing colorectal cancer compared with those of normal weight (BMI < 25 kg/m2) and people who are obese have an increased risk of bowel cancer and an increased risk of dying of bowel cancer when compared with people considered normal weight.
Long-term cigarette smoking increases a person's risk of developing bowel cancer due to the effect of carcinogens and development of polyps which can become malignant.
A study by Dr. Morten Gronbaek of the National Institute of Public Health in Copenhagen, has found that heavy drinkers (especially non-wine drinkers) significantly increase their risk of contracting rectal cancer.The findings are based on a population study of over 29,000 Danish men and women aged between 23 and 95.
Acromegaly is an endocrine disorder characterized by sustained hypersecretion of growth hormone (GH) with concomitant elevation of insulin-like growth factor (IGF) may increase your risk of colon polyps and bowel cancer.
14. Nigh shift work
Study that exposures to light at night suppresses the production of melatonin, a hormone that has antiproliferative effects on intestinal cancers. The result also suggested that working a rotating night shift at least three nights per month for 15 or more years may increase the risk of bowel cancer in women.
15. Previous Radiation Therapy for Certain Cancers
According to the U.S. Department of Health and Human Services, colon cancer has been caused by doses of about 1,000 millisieverts (mSv).
According to Heinz-Josef Lenz, M.D., professor of medicine at USC's Keck School of Medicine There has been increasing evidence that gender plays a significant role in the development and progression of bowel cancer are higher among men due to protective effect of female hormones.
Diagnosis and tests
Since bowel cancer is considered as one of most slow growth cancer and most of the discoveries are in the late stage and older than 50 years of age, implement bowel cancer screening methods can detect the cancer in its early stage resulting in a 29 percent drop in cancer deaths in 20 years.
1. Digital rectal exam
It is an internal examination of the rectum. The exam taken about a few minutes by first examining the external area (anus and perinium) for any abnormalities such as hemorrhoids, lumps, etc. Then, as the patient strains down, the physician gently puts a lubricated, gloved finger into the rectum through the anus and palpates the insides to check for large lumps for approximately sixty seconds.
2. Fecal occult blood test (FOBT)
It is the test to check for invisible blood in the stool. you are asked to eat red meats for a week to look for globin, DNA, or other blood factors including transferrin with the purpose is to detect subtle blood loss in the gastrointestinal tract.
An endoscope is an instrument used by your doctor to pass through a natural opening of the body or by a small incision. Depending to the circumstance, you doctor may refer either the rectum Sigmoidoscopy or whole colon Colonoscopy.
Sigmoidoscopy is a test to exam the large intestine from the rectum through the last part of the colon by either using a flexible endoscope (flexible sigmoidoscopy) or a rigid device (rigid sigmoidoscopy) to look for benign and malignant polyps, early signs of cancer in the descending colon and rectum, as well as any intestinal bleeding, inflammation, abnormal growths, etc.
Colonoscopy is a whole bowel examination to detect inflamed tissue, ulcers, and abnormal growths, benign and malignant polyps, early signs of cancer.
4. Double contrast barium enema (DCBE)
DCBE is a x-rays of the colon and rectum after injecting a liquid containing barium into the rectum to screen for bowel cancer and abnormalities. If there is any suspicious, your doctor may order a screening test such as a colonoscopy or sigmoidoscopy that we mentioned above.
5. Barium Enema
The exam, most of the time performs in the out patient in hospital and in the doctor office, you will be asked to move into different positions to get different views. Barium enema is the use of barium to highlight your large intestine and delivers air into the colon to expand it for better image as x-ray is taken.
6. CT Colonography scan and/or liver scan
a. CT colonography scan
With the same purpose, CT colonography scan is to screen for polyps or cancers in the large intestine by taking the cross-sectional images of bowel then be examined on a computer monitor, printed or transferred to a CD.
b. Liver scan
Liver scan is the test to gather information about liver and spleen function or used to help confirm that the tumor has spread with injecting a radioactive material called a radioisotope into one of your veins. After the liver has soaked up the material, under the scanner images are displaying on a computer.
7. Caricinoeembroyic antigen (CEA)
Caricinoeembroyic antigen (CEA) is a type of protein molecule found in many different cells of the body. CEA measurement is mainly used as a tumor marker to detect any recurrences after surgical resection, or localize cancer spread though dosage of biological fluids.
Treatments are depended totally in the stage and grade of the cancer of each patient. If the cancer is only limited to the mucosa such as a single layer of epithelial cells, a layer of connective tissue, and a thin muscle layer, than it can be cured in most cases. If the cancer have spread through the muscular layer of the bowel or the lymph note, the curable rate is lower. If the cancer has spread to other organs, the curable rate are even lower. Grade of the cancer is calculated dependently to how aggressive the cancer is.
1. Surgery and colostomy
Types of surgery is depending to the stage, grade and position of the tumor needed to remove, and surgery with complete removal of the cancer offers the best chance to cure the disease.
A colostomy is surgery to prevent the leakage of bowel content by diverting them away from the weaken part of bowel to prevent damage and infection after surgery to allow them to heal properly because of damage of bowel due to tumor removals to provide an alternative channel for feces to leave the body. After the weaken parts of bowel is recovered, further surgery is required to reconnect the bowel and close the colostomy.
Unfortunately, if the tumor is very close to the anus, bowel can not reconnected safely or in the late stage of the cancer, a permanent colostomy is required and small bowel is diverted to the surface.
2.1. Radiotherapy is the medical use of ionizing radiation to treat cancer by destroying the cancer cells but doing as little harm as possible to normal cells, if cancer happens to the place where surgery is impossible. In fact, radiotherapy has a minimum effect in treating bowel cancer.
2.2. Side effects
c. Frequent urinary
d. Sore skin in the treatment area
3.1. Chemotherapy, in bowel cancer used to stop the spreading of the cancer cells and is most helpful treatment for bowel cancer with moderate advance such as bowel cancer has only spread to bowel wall or to the lymph note with combination of some medications, such as 5-fluorouracil, leucovorin, and oxaliplatin (FOLFOX) with bevacizumab or 5-fluorouracil, leucovorin, and irinotecan (FOLFIRI) with bevacizumab, etc.
3.2 Side effects
b. Hair loss
c. Sore mouth
e. Sore eyes
4. Biological therapy
4.1. Biological therapies are new type of treatments in active research by using substances that occur naturally in the body, such as Cetuximab and bevacizumab are used to treat colon or rectal cancer that has spread to other parts of the body.
4.2. Side effects
c. Skin changes
d. A sore mouth, weakness
e. Loss of appetite
f. Low blood counts
g. Swelling of parts of the body due to a build up of fluid