Colorectal cancer is the third most common cancer in the world but screening and early detection can save lives By Kumudini Hettiarachchi Some have a “stalk”, others are sans stalks. With or without a stalk that is visible to the naked eye, it is an indication that there is a malignancy, MediScene learns. This is why [...]

The Sundaytimes Sri Lanka

Nip it in the bud


Colorectal cancer is the third most common cancer in the world but screening and early detection can save lives

By Kumudini Hettiarachchi

Some have a “stalk”, others are sans stalks. With or without a stalk that is visible to the naked eye, it is an indication that there is a malignancy, MediScene learns.
This is why it is very important, at the first signs of something having gone wrong to nip it in the bud, says Consultant General Surgeon Dr. Wasantha Wijenayake, for it may be a colorectal cancer.

While colorectal cancer is the third most common cancer in the world, in America it has been found to be the third highest cause of cancer deaths. The life-time risk of developing colorectal cancer is a terrifying 1 in 18.

Colorectal cancer, according to Dr. Wijenayake who has specialised in this field, can occur anywhere from the caecum to the anus. Affecting the epithelium or the lining of this part of the digestive tract, these cancers may be categorised into either colon cancer or rectal cancer. The colon is the longest section of the large bowel and the rectum the last part of the large bowel closest to the anus.

Usually, colorectal cancers start off as polyps. There are three types of polyps – hamartomatous mainly occurring in children, hyperplastic and adenomatous – but the ones which can give rise to cancer are the third type, MediScene learns.

Although 30% of the middle-aged and 50% of the elderly have adenomatous polyps, less than 1% of these polyps will become cancers, reiterates Dr. Wijenayake. The bigger the polyp, the higher its chances of turning cancerous – if it is more than 2.5cm as opposed to 1.5cm, then the risk is five times higher.

Explaining that colon cancers present themselves with stalks (pedunculated) or without stalks (sessile), he says the cancer could spread to other areas through blood or the lymphatics. The spread through blood could take the cancerous tentacles to the liver, lung and finally the bones, while the lymphatics could send them into the lymph nodes in the abdomen and then the chest. Lymphatics are small slim channels like blood vessels which carry tissue fluid or lymph. When the cancer spreads from its original site to other areas, it is dubbed “distant” or “metastatic” disease.

Quoting a study in the World Journal of Gastrointestinal Surgery of which he too was a part, he says that 75% of the large bowel cancers occur in the left colon, beyond the rectum, along the descending colon and the sigmoid colon.

Referring to the tests undertaken for screening for cancer, he names a few such as faecal occult blood test (FOBT), sigmoidoscopy and colonoscopy. Both the sigmoidoscopy and colonoscopy would double up as curative measures. The good news is that in countries such as the United Kingdom, colorectal cancer incidence has been halved (reduced by 50%) through colonoscopies.

“There is a five-year window of opportunity to deal with polyps which can turn into full-blown cancer. A colonoscopy — which gives a view of the large bowel and a part of the small bowel — when a person reaches 50, would help not only to detect adenomatous polyps but also remove them then and there. A year later, three years later and finally five years later, colonoscopies should follow to check for recurrence. Thereafter, a clean bill of health may be issued to the patient,” he says.

Colonoscopy reduces advanced (late-stage) cancer incidence by 70%, says Dr. Wijenayake, adding that surgery is the mainstay of treatment for colorectal cancer, which can be after or followed by chemotherapy, with or without radiation.

Get informed: Symptoms and risk factors

The main symptom of colorectal cancer, MediScene learns is rectal bleeding, with a flexible sigmoidoscopy being the baseline investigation, allowing a clear peek up to the splenic flexure.
The other symptoms include: change of bowel habits lasting over six weeks; loose stools; over three weeks of unintentional and unexplained weight loss; loss of appetite; exertional dyspnoea (becoming short of breath or panting after climbing stairs or walking a little faster than usual); unexplained abdominal pains, which could be for a long time or just a few minutes; feeling a mass or heaviness in the stomach; passing mucous with stools; a sense of incomplete emptying of the rectum even after going to the toilet; frequent passing of stools; spurious (false) diarrhoea which is getting the urge to go to the toilet but only discharging a tiny bit of watery stools with a lot of mucous; and a mass at the anus.
In the advanced disease there is also intestinal obstruction, distended abdomen, crampy abdominal pain, vomiting and not passing faeces or flatus (gas) but absence of constipation.
A drop in the haemoglobin level – 2gm for men and 3gm for women — of those especially over 50 is another indicator.
Risk factors, according to Dr. Wijenayake are:
Age — being older than 50.
Colorectal polyps – small growths on the inner wall of the colon or rectum.
A personal or family history of colorectal cancer – recurrence is higher in a person who has had colorectal cancer, while women who have had ovarian, womb or breast cancer are also at a higher risk. If close relatives have had colorectal cancer, once again the risks are higher.
Genetic changes – hereditary non-polyposis colon cancer (HNPCC) is a common inherited colorectal cancer while familial adenomatous polyposis (FAP) is a rare inherited type.
Ulcerative colitis or Crohn disease
Type 2 diabetes
Certain lifestyle factors such as high animal fat intake; tobacco use, smoking, physical inactivity, obesity and heavy alcohol use.

Cancer: Causes and stages

Tissues are made up of “building blocks” called cells, while organs are made up of tissues, says Dr. Wijenayake giving an insight into the workings within the human body. Usually cells grow and divide, forming new cells but sometimes this systematic happening goes awry, producing new cells even though the body does not need them, while old cells which should die do not do so.

This change in the cells produce tumours which could either be benign or malignant (cancerous), MediScene learns.
In the case of colorectal cancer, the trigger is the cells in an adenomatous polyp which begin to grow erratically and invade the muscle wall around them.
Cancers, according to Dr. Wijenayake, may be “staged” as follows:
Stage 0 when the cancer is found only in the innermost lining of the colon or rectum.
Stage I when the cancer has grown into the inner wall of the colon or rectum. This has the best prognosis, with the five-year survival rate for these patients being 90%.
Stage II when the tumour has extended deeper or through the wall of the colon or rectum. Although it may have spread into tissue close by, it has not got into the lymph nodes.
Stage III when the cancer has spread to the lymph nodes close by but not to other parts of the body.
Stage IV when the cancer has spread to other parts of the body including the liver or the lungs, the survival rate is less than 12%.

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