Individuals with cancer may not have any signs or symptoms, especially in early stage. Diagnosing cancer early can lead to early treatment, with much better prognosis and survival. Screening tests are available in some cancer and particularly useful for individuals who are at higher risk due to various reasons (such as age; their exposure to cancer causing agents or genetic susceptibility). Screening should be a part of the regular medical care.
Talk to your doctor to learn more about your risk of cancer and what screening tests you should have. Be sure to mention any family history of cancer.
What makes a good screening test
No screening test is 100% accurate, but a good screening test is one that results in a decrease in death rates in people with cancer.
Researchers also look for other benefits of screening including improved quality of life or less harmful treatments as a result of finding the cancer early.
The World Health Organization (WHO) suggests reviewing several factors before introducing a test as a screening tool for the general population. These include:
• Sensitivity – How effectively the test identifies people who actually have cancer.
• Specificity – How often a test give negative (normal) results for people who do not have cancer.
• Acceptability – Will the population who will benefit the most from the test (the target population) agree to be tested by this method.
Other consideration of a good screening test includes the overall cost and benefit of screening. A good screening test should be cost effective in detecting the disease and benefit a large population at risk.
Early Diagnosis of Cancer
The best results for treatment arise when cancer is found early. The reason is because there is less opportunity for the disease to spread and metastasize to other parts of the body. Direct observation is often used for visible cancers, but even by this time the tumor volume is millions of cells in size. Ideally, cancers should be identified by early stage biomarkers in the blood or tissue sample. In this way, a marker would indicate that a particular cancer is present; for example, specific metabolic or protein by-products, or in the case of a viral infection, fragments of the viral genome would be evident.