By EBELE ORAKPO

CANCER, the dreaded six-letter word, is considered one of the most feared disease conditions on earth. Unfortunately, scientists have not been able to pinpoint what exactly causes cancer. They, however, believe that the only solution is early detection/diagnosis.

So a team of  physicians led by Dr. Austin Obichere, consultant colorectal surgeon, and Director, Bowel Cancer Screening Programme at the University College, London Hospital came up with a novel screening tool for colorectal cancer to aid the early detection of colon cancer. In this chat with Vanguard Learning, he speaks on the incidence and methods of detecting colorectal cancer. Excerpts:

Scope of the problem:
“Colorectal cancer is a major health hazard worldwide. It is estimated that at least, three quarters of a million people are diagnosed with colon cancer each year worldwide and that a quarter of a million people will die. Most of the data we  have relate to the western world because they have statistics. I recall when I was a student, we thought colon cancer was not a disease of black people, that it was related to westerners because of their diet lacking fibre and bran whereas African foods are typically rich in fibre and bran.

But I will argue with those who say that colon cancer is rare in Africa because it is not. Emerging data and research show that colon cancer is indeed common in Africa and it appears to be occurring in young Africans, people under the age of 50 years. What is really worrisome is that these cancers are usually very advanced when they present unlike in the western world where the commonest age incidence of colon cancer is found in people in their late 60s and early 70s but in Nigeria, the peak age incidence for colon cancer is about 44 years; a dramatic difference,” said Obichere, founder and MD of Lagos-based Diagnostic & Therapeutic Endoscopy Centre.

Globalisation:
“Is it because the cancer had always been around, we just have not had the facilities, infrastructure and technology to diagnose it or is it because of  globalisation where Africans, particularly Nigerians, are well travelled and now eat western diets that we previously had attributed to one of the causes of colon cancer? Personally, I suspect that the disease has  always been there but now, we have more sophisticated equipment to be able to diagnose it.

Unfortunately we cannot tell you, certainly in Nigeria, the exact incidence because as you know, we have poor record-keeping unlike the western countries that have maintained statistical databases for decades and they are looking at how they can cure cancer. There is a lot of research in the area of coloproctology,  seeking how to reach the holy grail in the management of colon cancer.

Colorectal cancer is a unique cancer in that it has an early form known as polyps which are entirely benign growth in the lining of the bowel that can over time, progress to become cancerous. The next big question is; why do they become cancerous? There are lots of environmental influences we do not fully understand and indeed, there are some people that basically carry that gene, in other words, it runs in families so again, this is all a subject of research.”

Prevention/Cure:
“The only known method worldwide through which you can achieve this is by identifying the disease in the early forms, hence the concept of screening. If you can screen your population and find this early form of potential cancer (polyps), you can actually remove them and prevent the patient from developing colon cancer. Furthermore, if they do already have cancer, it is likely you are going to pick up the early form of the cancerous growth before it spreads beyond the bowel walls.”

Levels:
“There are basic grading systems to assess the severity of the cancer. If it is still within the bowel wall, it is classified as Duke’s A or B; if it has spread to the lymph glands, it’s a C and if it has spread to distant organs such as the liver, lungs, bones, brain etc., then it’s a D.

“So screening has become a very important clinical service in Nigeria and West Africa. In the western world, it is a phenomenon that is taken as a way of life so people within specific ages undergo screening methods to try and identify the early forms of the disease to save lives,” said Obichere.

Screening methods:
“There are different methods of screening but we have not quite identified that absolute holy grail. In other words, what single test, or what single stool or blood test that we can carry out that will say yes, Mr. A or Mr. B has colon cancer that is conclusive. There are current techniques that are good such as Fecal Occult Blood Test (FOBT) where we basically are testing for blood in stool. The presence of blood in your stool does not mean that you have cancer, it means that you probably need further investigations to identify the cause of bleeding.

“There is Barium enema which is quite common in Nigeria. It is still very popular in the third world because it is cheap and simple to administer but many patients find it intolerable so it has largely been abandoned as a form of screening in the western world.”

Modern screening methods:
Colonoscopy – “Direct visualisation of the entire large intestine using fibre-optic flexible telescopes remains the gold standard. You can diagnose disease and also remove early stages of cancer such as polyps and thereby prevent its development. In Nigeria, adults above the age of 40 years should undergo a colonoscopy every five years because it has been shown that the peak age incidence of the disease in adults (men and women) is 44 years. If you are considering a screening colonoscopy, ensure that the doctor performing the procedure is adequately trained and experienced to minimise the risk of complications.

“CT Pneumocolon/CT Colography/ Virtual Colonoscopy:
All these terms are interchangeable. Patients are put through a high resolution CT-scanner, air is introduced through the anus and using special software, a three dimensional reconstruction of the large intestine provides excellent images of the inside of the bowel. Pre-cancerous polyps measuring 5mm or more in diameter are easily identifiable but cannot be removed or destroyed.

The patient would need to have a colonoscopy to remove the polyp or take tissue samples. One serious drawback of Virtual colonoscopy is that the patient is exposed to radiation many times in excess of that received with a simple chest X-ray. This unfortunately may result in the development of some types of cancer later on in life.

Tumour markers in blood, urine or stool: “The holy grail for researchers in the field of colorectal cancer is the identification of a simple test that will diagnose bowel cancer from blood, urine or stool sample. This is the subject of numerous research and clinical trials worldwide. Our study – DNA quantification of exfoliated colonocytes as a novel screening tool for colorectal cancer, was recently published in Eur J Surg Oncol; 2013 Dec: 1423-7, indicating that abnormal cells retrieved from the surface of the rectum are sensitive for colorectal cancers. This new approach holds much promise as a future screening tool for colorectal cancer,” he enthused.

Capsule Colonoscopy: “Similar to capsule endoscopy, a pill is swallowed (a small camera)which transmits pictures of the large intestine to a monitor or TV. Recent attempts by manufacturers to include tiny robots in the pill so that polyps or other lesions in the colon can be removed or biopsied have reached an advanced stage. It is anticipated that this new exciting technology should become widely available in the next five years and could replace colonoscopy as the gold standard,” he stated.