Cancer screening & diagnosis at a glance
- Cancer screening consists of tests that detect and confirm the presence of cancer, or conditions that can become cancerous, before symptoms arise.
- The primary benefit of cancer screening is catching cancer early or even before it starts, which generally increases the chance of successful treatment.
- Cancer screenings vary by the type of cancer screened for and may include biopsies, physical exams, imaging and blood tests.
- If cancer screening reveals a positive result, an oncologist will determine the diagnosis, including the stage and location of the cancer.
- Cancer screening poses some risks and considerations, such as the chance of false-positive results, as well unnecessary procedures that may cause physical damage to the body.
Cancer screening & diagnosis programs at cCARE
What is cancer screening & diagnosis?
Cancer screening comprises tests that detect cancer, or conditions that may evolve into cancer, before symptoms appear.
According to the National Cancer Institute, cancer screening reduces the risk of dying of certain cancers and increases the chance of successful treatment in many cancers. Detecting a cancer in the earlier stages often means the cancer has not spread (metastasized) and will be easier to treat than if it had spread.
A cancer diagnosis follows a positive cancer screening. The oncologist’s diagnosis includes staging (the process of determining how advanced the cancer is), where the cancer is located and whether it has begun to spread.
Common types of cancer screening
A number of cancer screening tests are available and vary according to the type of cancer screened for. Screening may include a physical exam, blood tests, biopsies, imaging procedures and genetic testing.
The most common cancer screening tests include the following.
During this physical exam that tests for colorectal cancer, a doctor examines the inner lining of the colon and rectum (large intestine) to check for precancerous and cancerous cells using a colonoscope (a flexible, thin tube).
During a colonoscopy, a doctor collects tissue to biopsy and check for abnormalities or remove irregular growths throughout the inner lining of the large intestine.
An imaging exam that screens for breast cancer, a mammography uses low-dose X-rays to look for cancer cells in the breast tissue.
Low-dose helical computed tomography
This form of CT scan exam screens for lung cancer. A patient lies horizontally while the machine scans the patient’s torso by rotating in a spiral motion around the torso.
Pap and HPV testing
A pap test screens for cervical cancer and an HPV screens for the human papillomavirus, which can lead to cervical cancer. These tests can detect precancerous cells so that preventive procedures can treat the cells before cancer begins to grow.
Pap and HPV screening is performed by taking a sample of uterine cells in an office and sending it to a lab.
The prostate-specific antigen (PSA) is a lab test that indicates the possible presence of prostate cancer from a man’s blood sample. The test is carried out by measuring the level of PSA, which is the protein that malignant and benign prostate cancer produces.
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How is cancer diagnosed?
Cancer is diagnosed by a combination of physical exam, screening methods mentioned above and diagnostic tests. Following a positive result from cancer screening, an oncologist will diagnose the type of cancer. An accurate diagnosis is necessary to determine a proper course of treatment.
A cancer diagnosis varies by the type of cancer, the staging and whether the tumor has moved to other parts of the body (metastasized). General staging includes a scale from 0 to IV. Stage IV means that the cancer has spread to distant organs or body tissues, and stage 0 typically represents precancerous cells.
All cancers will be staged upon initial diagnosis. The stage will affect the initial treatment course. For example, earlier stage cancers can typically be treated solely with surgery to remove the cancerous or precancerous cells, while later stage cancers may require a combination of surgery, radiation chemotherapy or targeted therapies.
Cancer screening risks & considerations
Although cancer screening saves lives every year, there are some limitations and risks to consider. The possibility of both false-positive and false-negative results is a major consideration of cancer screening, as the tests are not flawless.
Patients should consider the following.
- A false-positive test occurs when the test results indicate cancer and the patient receives a cancer diagnosis, when in fact there is no cancer. This causes undue anxiety, unnecessary procedures and further testing that can cause both physical and emotional harm to the patient.
- A false-negative exam, which indicates there is no cancer present when there actually is, can be equally harmful because this causes a delay in treatment (usually until symptoms begin and cancer is more advanced).
- Screening for and confirming a cancer diagnosis may not actually extend a person’s life. It may reduce quality of life, as some treatments cause side effects and never cure the cancer.
- Screening can result in overtreatment of cancer, which involves treating certain cancers that grow slowly or occur later in life and would never end up killing a patient. The treatment side effects may be worse for the patient than the effects of cancer.
- Cancer screening may also cause some physical issues including excessive bleeding and damage to tissue due to biopsies, and heavy bleeding at the site of screening. For example, colonoscopies (the screening test for colorectal cancer) can damage the lining of the colon.