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Scientists are constantly devising tests in order to detect cancers before the signs and symptoms are seen. These tests are known as screening tests. The objective of a screening test is:

1. Reduce the number of people who will die from the disease (eliminate deaths due to cancer)
2. Reduce the development of cancer

Each cancer has its own different kind of screening tests. Not all screening tests are effective but they do give a general idea. Here are some of the screening tests for common cancers. 

Breast Cancer

• Mammography : It is a type of x ray which is specific to the breast. It can show irregularities and tumors in the breast tissue. It has to be done every year.
• Clinical breast examination : a clinical personnel will examine the breast for changes in the breast shape, size also the skin and the nipple. It has to be done every 3 months.
• Self breast examination : this examination is done by the woman herself to examine any changes in her breast. In case she notices any change, she must see the doctor.It has to be done monthly.
• MRI : Magnetic Resonance Imaging is not used often but only in cases of high risk for breast cancer or for those with dense breasts.

Cervical Cancer

• Human Papillomavirus (HPV) Test : cells are scraped from the woman’s cervix and  tested for strains of HPV. Certain strains have been found to be high risk for cervical cancers. HPV test can be done in combination with a pap test
• Pap Test : This test is also done on the cervix of the woman to identify precancerous lesions or cancerous cells. As mentioned earlier, this test can be combined with the HPV test.

Colorectal Cancers

• Colonoscopy :This procedure involves a long flexible tube which the doctor will insert into the rectum. The doctor can visualize polyps or cancer in the colon. It has to be done every 5 year.
• Sigmoidoscopy : Again the doctor will use a small flexible tube to visualize the lower part of the colon for polyps and cancer cells. It has to be done every year.
• Fecal Occult Blood Test (FOBT) : This test finds blood in stool which is usually a sign of polyps or cancer
• Double Enema Barium Enema : This is an x ray examination of the colon and rectum. The enema will help to outline the colon for the x ray. This test is used for patients who cannot undergo a colonoscopy.
• Stool DNA testing :  This tests for the DNA in stool for cancer. The DNA changes seen in polyps or cancer are detected to see if a colonoscopy is necessary

Head and Neck Cancers

• General Health Screening Examination : The doctor will examine the nose, mouth and throat for abnormalities and check the neck for lumps (swollen lymph nodes)

Lung Cancer

• Low-dose Helical or Spiral Computed Tomography Scan : The CT scan will create a three dimensional image of what is inside the body with an x ray machine. The computer creates a cross sectional image to show abnormalities and tumors.

Prostate Cancer

• Digital Rectal Examination:  The doctor inserted a gloved finger into the rectum to examine the prostate for irregularities.
• Prostate Specific Antigen (PSA) Test: this is a type of blood test which checks for the level of PSA. In case of prostate cancer, PSA levels are usually higher than normal. High levels of PSA is not always conclusive of cancer.

Skin Cancer

• Complete skin examination:  The doctor will do a thorough examination of the skin for any signs of cancer
• Skin Self examination: The person will check themselves thoroughly in a mirror to see for any signs of abnormality.
• Dermoscopy: a handheld device is used to examine areas of the skin which are pigmented or different. Dermoscopy is helpful for early detection of melanoma.

Screening Risks:

Screening tests are most effective in early detection of cancers, usually at a more treatable stage which in turn improves survival. However, screening tests do come a with a percentage of risk.

• Overdiagnosis : some tests could find a slow growing cancer which would potentially not post as a threat to the person during his lifetime. As a result of these tests, the person may receive harmful drugs which will cause stress and pain even when they may not require it at all.
• False positives : some tests can detect a cancer when there isn’t one.
• Increased testing :  Doctors may run additional tests which can be invasive, costly and unnecessary only because of false positives or overdiagnosis.
• False reassurance : Sometimes a test may miss out on detecting a cancer  when the person actually has one. As a result the person may not recieve treatment when they require it.

Authored By : Dr. Shiva Kumar Uppala