Problems related to bowel habits -- constipation, bleeding due to haemorrhoids or piles to name a few are quite commonly seen with ageing. Most are related to variations in the norm. Yet, it is worthwhile being concerned about recent changes, as some could be a pointer to an underlying disease in the intestines.
This week Dr. Nalitha Wijesundera, Consultant Surgeon at the Teaching Hospital Karapitiya speaks about cancers in the large bowel (colon) and the rectum, known as ‘colorectal cancers’.
Cancers of the large intestine and the rectum are common, and are the third commonest cause of cancer deaths worldwide, and also the third commonest cancer to be diagnosed. There was a belief that the high fibre diet commonly consumed in Asian countries protected against this cancer. However, currently the prevalence in this part of the world is also on the rise. Moreover, it has been found that 70% of all cancer deaths worldwide do occur in the low or middle income countries.
“The problem we see among our population is late presentation; over 90% who present with early disease do well where survival rates are concerned,” says Dr. Wijesundera, stressing that for effective treatment, seeking medical advice early is important. Late presentation would drastically lower the possibility of being cured as well as the duration of survival.
Unfortunately early symptoms of colorectal cancer are vague; early cancer being symptomless. To add to the problem the symptoms are also attributed to the normal ageing process and neglected until the disease is advanced.
Bleeding from the rectum is one of the most important symptoms. Blood stained stools or blood splashing the pan while passing stools is common with haemorrhoids or piles. Piles are much more common than cancers. Yet, recent onset rectal bleeding needs further investigation before attributing it to piles. This is especially important in a person over 40 years with recent onset of bleeding per rectum, because haemorrrhoids can be caused by a lesion higher up in the colon pressing on the blood vessels.
The other symptoms would be recent alteration of bowel habits, i.e. alternative periods of constipation for days followed by diarrhoea or loose stools; feeling of incomplete evacuation of bowels following passage of stools, and also left-sided lower abdominal pain would warrant further investigations. Unexplained anaemia, weight loss or loss of appetite are also not to be neglected, even though none of these symptoms are conclusive of cancer.
Risk factors
Colorectal cancer is rare before the age of 50, unless one has another strong risk factor, such as genetic disorders where one is genetically susceptible to early cancer, due to alteration of genes. Such conditions are hereditary -- non polyposis coli (HNPC) and familial adenomatous poliposis (FAP) among them. If more than one of your immediate family members (parents/ siblings) were affected with the condition, especially at an early age (below 50) it is necessary to seek medical advice about early screening.
People with strong family history of rectal cancer though they do not have the above mentioned diseases, would have an increased risk too. Patients who have had a cancer in the intestine, breast, uterus or the ovary will also have a higher chance of getting a second tumour in the large intestine. Polyps or mucosal growth in the inner skin lining of the gut also would be a risk factor. Although these polyps are not cancerous in the beginning, they can transform into cancers later on.
There is accumulating evidence, though still not confirmed that low fibre, high fat diets and processed meat increases the risk of intestinal cancers.
Investigations
“People with risk factors do need surveillance colonoscopy from an early age depending on the risk they have. Also it is important in investigating patients with symptoms, especially symptoms of recent onset,” stresses Dr. Wijesundera.
Colonoscopy is the gold standard investigation to diagnose colorectal cancer. This procedure involves visualizing the whole of the large bowel up to the terminal part of the small bowel with a tube with a camera, called the ‘colonoscope’. Whenever a suspicious area is identified through the camera in the tube, it is possible to take a small piece of it for biopsy to be examined under the microscope for the presence of cancer cells.
Before colonoscopy it is necessary to prepare the patient’s bowel with laxative so that all fecal matter is emptied, so that it is possible to see all the inner sides of the intestine. While taking laxatives the patient has to take adequate water and other liquids to prevent dehydration from severe diarrhoea.
“Before going for full colonoscopy, a sigmoidoscopy can be done, where a harmless lesion is suspected at the rectum or the distal part of the colon,” explained Dr. Wijesundera. However the principle of both the investigations is the same. But sigmoidoscopy visualizes a limited distance from the anal verge. Sometimes this is adequate to exclude a problem in the lower part of the bowel. But if a cancer is diagnosed with the sigmoidoscope it is mandatory that full colonoscopy is done to exclude a second tumour higher up the colon.
Once a tumour is diagnosed, a CT scan of the abdomen will be used to assess the spread. MRI scanning is also a valuable investigation for rectal cancers. The spread of the cancer in the bowel and to the other organs like the liver helps in determining the treatment methods. Also several blood tests are needed to assess the effects of the cancer and the patient’s fitness for surgery. A blood test named ‘CEA’ or carcinoembryonic antigen is a marker of colorectal cancer, and the levels will be high in the patients with cancer. Moreover CEA levels will help monitor the disease activity once the cancer is surgically removed.
Treatment is primarily surgery to resect the tumour. If well localized even secondary deposits in the liver too can be resected. Surgery involves removing the diseased part of the colon with an adequate margin of tumour free tissue. Radiotherapy and chemotherapy or anti cancer medication is also helpful, sometimes even before the operation to downstage the disease.
When the diseased part of the colon is removed, usually the two cut ends can be sutured together to maintain the continuity of the bowel. However, there can be instances where a stoma is made, to expel the waste products. Stoma is when a part of the bowel is brought out at the abdominal wall and fixed so that it opens to the outside through the abdominal wall.
A colostomy bag covers this opening to collect the fecal matter. Usually colostomies can be reversed after some time. But in very low cancers in the rectum, where the anal sphincter or the fecal controlling valve is affected, it is necessary that the colostomy is in place permanently. This is because when the diseased part of the rectum is removed the mechanism that maintains fecal continence is also disturbed. Hence, in these cases it is best that the expulsion of fecal matter is to a bag that fits the abdominal wall. This bag can be emptied once it is filled.
“True it involves lot of psychological trauma initially but with good support patients do cope well,” explains Dr Wijesundera, saying that colostomy is not something to be afraid of. Once the patient is used to it, it hardly affects his/her daily routine. There are trained colostomy care nurses who would train patients to change their colostomy bags and support them until the patient is independent.
Patients with colorectal cancers need to be followed up for life, as recurrences could occur. This can be done with blood tests like CEA levels, surveillance colonoscopy and ultrasound scan of the abdomen.
Newer techniques in treating colorectal cancer include laparoscopic surgery, where the tumour is removed by a small cut in the abdomen.
Colorectal cancer is not a rare form of cancer, but with early presentation and early treatment patients can lead quite a normal life. |
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