Cancer screening to match resources

SCREENING TESTS can help find cancer at an early stage, before symptoms appear. When abnormal tissue or cancer is found early, it may be easier to treat or cure. By the time symptoms appear, the cancer may have grown and spread and this can make the cancer harder to treat or cure.

It is important to remember that when your doctor suggests a screening test, it does not always mean he or she thinks you have cancer. Screening tests are done when you have no cancer symptoms.

According to Dr Tamu Davidson, director of non-communicable diseases and injuries prevention at the Ministry of Health and Wellness, a screening test is not intended to be diagnostic. “Screening is the presumptive identification of unrecognised diseases or defect by the application of tests, examinations or other procedures which can be applied rapidly. Screening tests sort out apparently well persons who probably have a disease, from those who do not,” she said.

If you get a normal result after a screening test, this means you are at low risk of having the condition you were screened for. This does not mean you will never develop the condition in the future, just that you are low risk at the moment.

If you have a screen positive result, it means you may have the condition that you’ve been tested for. At this point, you will be offered further tests, called diagnostic tests, to confirm if you have the condition. You can then be offered treatment, advice and support.

“A screening programme is not just a single test, but a process and a pathway. It includes diagnosis and treatment. It will only be effective if all parts of the screening pathway are provided correctly,” she said.

“Finding out about a problem early can mean that treatment is more effective. However, screening tests are not perfect and they can lead to difficult decisions about having further tests or treatment,” Dr Davidson said.

The purpose of cancer screening tests is to detect precancer or early-stage cancer in asymptomatic individuals, so that timely diagnosis and early treatment can be offered, where this treatment can lead to better outcomes for some people.

“The World Health Organization (WHO) recommends screening for cervical cancer, breast cancer and colorectal cancer with organised and high-quality programmes that are linked to timely treatment,” Dr Davidson said.

Screening tests usually do not diagnose cancer. If a screening test result is abnormal, more tests may be done to check for cancer. “For example, a screening mammogram may find a lump in the breast. A lump may be cancer or something else. More tests need to be done to find out if the lump is cancer. These are called diagnostic tests. Diagnostic tests may include a biopsy, in which cells or tissues are removed so a pathologist can check them under a microscope for signs of cancer,” Dr Davidson said.

The aim of a cancer screening programme, she said, is to reduce mortality and morbidity in a population, to reduce the incidence of cancer by identifying and treating its precursors, and to target people who are at higher risk of a particular cancer because of a behaviour or genetic predisposition.

Types of screening programmes include organised cancer screening, opportunistic screening and multiple screening tests at the same time, as part of routine and adult health checks.

“The WHO recommends that population-based screening programmes should only be implemented when their effectiveness has been demonstrated, resources are sufficient to cover the target group, facilities exist for confirming diagnosis and ensuring treatment, and the disease’s prevalence justifies screening,” Dr Davidson said.

Colorectal cancer screening programmes require significant resources for testing large number of people and ensuring adequate and timely follow-up of individuals with a positive test, compared to other non-communicable diseases.

“Most screening programmes use stool-based testing on faecal occult blood test (FOBT) or fecal immunochemical test (FIT). Programmes move from the inexpensive, less accurate FOBT to more sensitive and reliable FIT; and a positive test is then followed by a colonoscopy, or flexible sigmoidoscopy. Small number of programmes use colonoscopy, or flexible sigmoidoscopy, as a screening rather than diagnostic tool,” Dr Davidson said.

The overall goal of screening, she said, is to provide optimal care for patients, while considering the unique challenges of cancer screening in resource-limited settings so that persons can make a more informed decision.

“Screening invites people in a target population who do not have symptoms to undergo testing. Early diagnosis is the recognition of symptomatic cancer at an early stage,” Dr Davidson said.

keisha.hill@gleanerjm.comSOURCE: Jamaica Cancer Society, World Health Organization