It’s time to prevent Colon Cancer through screening | Daily News

It’s time to prevent Colon Cancer through screening

Community physicians present evidence:

No matter your age, one of the most important things you can do to stay healthy is to know and to be knowledgeable and alert to symptoms that might be early warning danger signs. Most people are aware of danger signs and symptoms of more high profile cancers, and even though colon cancer is not something much talked about, it should receive the same attention as others as it is the third most common cancer in the United States and the fourth and the sixth leading cancer among men and women in Sri Lanka respectively according to a study published in a peer reviewed journal 2018.

This study has generated evidence towards the need for a routine population level national screening programme for colorectal cancer which is not established in Sri Lanka as yet.

In the absence of a screening programme, Sri Lanka uses flexible sigmoidoscopy or colonoscopy for diagnosing colorectal cancer in patients with symptoms in an ad-hoc manner.

Clear evidence on its high burden and better survival associated with early detection signifies that Sri Lanka will benefit from introduction of a cost effective and affordable screening programme for colorectal cancer. However, being a low- and middle-income country, our country cannot afford to provide colorectal cancer screening services using colonoscopy or flexible sigmoidoscopy as it is done in most western countries.

As an alternative, evidence suggests that it would be efficient to follow a two-step process where population groups at risk, identified from risk stratification directed for further screening. The importance of this cancer was highlighted by choosing it as the subject for the A. V. K V. De Silva oration of the College of Community Physicians, and the orator was Dr. Yasara Samarakoon.

During her oration, Dr. Samarakoon explained the goals of a colorectal cancer screening programme. One is to identify and remove precancerous polyps, and thereby reducing the incidence and also to detect any cancerous growth at an early stage when curative therapy is most likely possible and thereby reducing the mortality.

Early detection and treatment

She went on to explain how the effectiveness of screening is affected by a multitude of factors including lack of accessibility, limitations of test performance and suboptimal screening compliance which has resulted in a marked variation in colorectal cancer incidence and mortality globally. These controversial aspects have created the dilemma of adopting a screening programme for colorectal cancer.

The argument of the effectiveness of colorectal cancer screening is based on the survival rates. Survival rates of colorectal cancer are based on the stage of the disease at the time of diagnosis. An early stage colorectal cancer which has not extended beyond the bowel wall is associated with a five-year survival of more than 90% of the patients. However, the five-year survival decreases up to 70% for patients with tumours with lymph node involvement and to less than 15%, if metastases are present. This shows that colorectal cancer shows good improvement of survival with early detection and treatment.

Dr. Samarakoon explained that current colorectal cancer screening methods are divided into two types, invasive and non-invasive tests. Non-invasive tests include stool based, radiologic tests and blood-based tests. Radiological tests include Double contrast barium enema, Capsule endoscopy and Computed tomographic colonography. Invasive tests include Flexible sigmoidoscopy and Colonoscopy. Flexible sigmoidoscopy screens for adenomas using a flexible endoscope inserted into the distal colon, examining the rectum and sigmoid and, if possible, as far as the splenic flexure. Colonoscopy could detect and resect neoplasia and precancerous lesions across the entire large bowel and is the definitive examination when other screening tests are positive.

Despite the wide range of screening options, colorectal cancer screening is still underused by populations. Screening rates remain around 60% since 2010. Despite having many modalities, along with the fact that screening has noticeably been shown to reduce the risk of colorectal cancer associated mortality, its effectiveness is jeopardized by a multitude of factors. Barriers to screening include elevated cost, lack of proper education regarding colorectal cancer, under appreciation of the benefit of screening, a sense of fatalism, or simply fear of the screening test. Evidence from developed countries suggests that it is more efficient to offer colorectal cancer screening using colonoscopy or flexible sigmoidoscopy to high-risk population groups rather than to all as a routine screening test.

This has prompted many countries to explore the use of high-risk screening for colorectal cancer with appropriate risk stratification of individuals. Of the tools to assess the individualized cancer risk, risk prediction models which are simple and can be applied in a community setting by a trained person are considered as useful. Risk prediction modelling is a mechanism which estimates the probability of an individual having a certain condition based on presence of multiple risk factors. The country has developed and validated a country specific risk prediction model for Sri Lanka and application of the model as a cost-effective method to identify the high-risk group for screening.

A study conducted on the “Prevalence of the population ‘at risk’ of developing colorectal cancer in Sri Lanka” by Dr. Samarakoon and others was done mainly to advocate for a screening programme for colorectal cancer in the country. It conducted in the light of evidence of increasing colorectal cancer burden in Sri Lanka in the near future.

Dr. Samarakoon explained that a comprehensive Scoping review that examined all the available risk models and scores for colorectal cancer as the first step identified 58 risk prediction models that were mainly developed from case control or cohort studies. The study found out that 12 out of every 100 people as being at risk of developing colorectal cancer. While it indicated the need for advocating a screening test for colorectal cancer in Sri Lanka within the existing health system, it further highlighted the logistical difficulties in offering follow-up diagnostic tests to all those who were screened-positive.

Sri Lanka offers free healthcare services and has initiated healthy lifestyle centres at the lowest level of primary care institutions since 2011 to offer adults a structured non-communicable disease screening service. More than 800 such centres are distributed throughout the country at present.

The main service objective of healthy lifestyle centres is to reduce the risk of non-communicable diseases of 40-65-year-old adults by early detection of risk factors and the disease improving the access for specialized care for those found to be at high-risk and could be extended to colorectal cancer screening as well.

Dietary guidelines

Addressing dietary risk factors for colorectal cancers, it is advised to avoid long-term frequent consumption of deep-fried food and frequent consumption of red meat as a primary preventive measure. Noting that these foods are discouraged in the existing national dietary guidelines and school canteen policy, the evidence recommends strengthening their implementation.

With the availability of a risk prediction model for early detection of colorectal cancer, the scope of healthy lifestyle centres can be extended to cancer screening. Such an initiation should be accompanied by informing the general public on the burden of colorectal cancer in the country and the importance of getting the risk estimated and if required undergoing further tests to diagnose the condition early, enabling successful treatment. In view of a substantial proportion of adults being at risk for developing cancer, it is recommended that those at ‘high risk’ be directed for diagnostic colonoscopy examination and further management while the moderate risk be advised on directed for simple screening tests such as fecal occult blood tests or modifying the modifiable risk factors and identification of early symptoms and signs of colorectal cancer.

The authors of the study further advocates introducing a screening programme in Sri Lanka is to establish a referral system and services for those found to be ‘at risk’ to undergo colonoscopy or flexible sigmoidoscopy in a hospital setting. This information should form the basis to look at a policy decision to evaluate the potential for a screening programme for colorectal cancer among the high-risk population in Sri Lanka. The relatively high ‘at risk’ prevalence denotes the burden of colorectal cancer on the health system in future. It is likely that the quality of life and survival of colorectal cancer will be improved by early detection, if the risk prediction model is successful at Healthy Lifestyle centres at primary care level.

Both men and women are equally at risk and it is most common among people aged 50 and older but can occur in patients as young as teenagers. Over 75 percent of colon and rectal cancers happen to people with no known risk factors, which is why regular screening is so important. A personal or family history of colon cancer or colon polyps can increase the risk of developing colon cancer.

People with a parent, sibling, or child with colorectal cancer are two or three times more likely to develop the disease compared to those with no family history. When the relative was diagnosed at a young age or if there is more than one affected relative, the risk increases to three to six times that of the general population. About 20% of all colorectal cancer patients have a close relative who was diagnosed with the disease. Other main risk factors include, physical inactivity, being overweight or obese, high consumption of red and/or processed meat, tobacco smoking and people with very low fruit and vegetable intake. Studies have further shown that consumption of milk and calcium probably decreases the risk of developing colorectal cancer.

 


 

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