Types and Importance of Cancer Screening

February 11,2021
30 Min Read

Cancer screening implies checking for cancer in asymptomatic people. Screening can help find several types of cancers early, before they manifest clinically. Early detection is important because it allows early treatment and offers greater chances of recovery and even cure. By the time symptoms appear, the cancer may have begun to metastasize and be harder to treat.

But it is important to keep in mind that, screening tests have both pros and cons:

- Overdiagnosis: The screening test correctly shows that a person has cancer, but it might not clearly indicate that the cancer is slow-growing and would not have harmed that person in his or her lifetime, leading to unnecessary treatment.

- False-positives: The test indicates that cancer may be present even though it is not. False-positive test results can cause anxiety and are usually followed by additional tests and procedures that also have potential side-effects.

- False-negatives: The test fails to detect the presence of cancer. False-negative test results may lead to a false sense of security, leading to delays in diagnosis and possibly causing an individual to put off seeking medical care even if symptoms develop.

TYPES OF CANCER SCREENING TESTS:

Not all cancers currently have screening tests, but those that do have specific tests.

Breast Cancer:

- Mammography

- Clinical breast examination

- Breast self-examination

WHO Recommends -

Age group	Screening
<40 years	Not recommended
40 - 49 years	Only as part of organized population-based screening programs
50 - 69 years	Mammogram: Every 2 years
70 - 75 years	Only as part of organized population-based screening programs

The U.S. Preventive Services Task Force (USPSTF) recommends that women ages 50 to 74 have mammography every 2 years. They recommend that mammography be considered in women ages 40 to 49 after evaluating the risk and benefits of this test with a doctor.

Cervical Cancer:

- Pap smear examination - Conventional or the recommended Liquid Based Cytology (LBC) testing

- Human papillomavirus (HPV) testing

Visual inspection with acetic acid (VIA) is a screening test that can be done with few tools and the naked eye. This screening test is very useful in places where access to medical care is limited.

The ACS/ASCCP Cervical Cancer Screening Recommendations 2020 -

Age/Condition	Screening
<25 years	No screening
25 - 65 years	Starting at age 25, primary HPV test ALONE every 5 years (PREFERRED), or co-testing every 5 years, or Cytology alone every 3 years
>65 years	Discontinue if adequate negative prior screening. Individual >65 years without adequate negative history should continue screening till conditions of cessation are met.
After hysterectomy	Individuals without a cervix and without a history of CIN2 or a more severe diagnosis in the past 25 years or cervical cancer ever should not be screened
HPV vaccinated	Follow age - specific screening recommendations (same as unvaccinated individuals)

*Adequate negative prior screening (condition of cessation) is currently defined as 2 consecutive, negative primary HPV tests, or 2 negative co-tests, or 3 negative cytology tests within the past 10 years, with the most recent test occurring within the past 3 - 5 years.

Colorectal cancer:

Five types of tests are used to screen for colorectal cancer (CRC):

- Faecal occult blood test (guaiac faecal occult blood / faecal immunochemical test)

- Sigmoidoscopy

- Colonoscopy

- Virtual colonoscopy (CT colonography)

- Stool DNA test

Studies have shown that screening for colorectal cancer using digital rectal exam does not decrease the number of deaths from the disease.

American Cancer Society recommendations for Colorectal Cancer Screening -

Average Risk	Age/Condition	Screening
They DO NOT have: A personal history of colorectal cancer or certain types of polyps A family history of colorectal cancer A personal history of inflammatory bowel disease (ulcerative colitis or Crohn’s disease) A confirmed or suspected hereditary colorectal cancer syndrome, such as familial cancer syndrome, such as familial adenomatous polyposis (FAP) or Lynch syndrome (hereditary non-polyposis colon cancer or HNPCC) A personal history of getting radiation to the abdomen (belly) ir pelvic area to treat a prior cancer	<45 years	No screening
	45 - 75 years	Screen with: Occult blood test every years, or Stool DNA test every 3 years, or Colonoscopy every 10 years, or CT colonography every 5 years, or Sigmoidoscopy every 5 years
	76 - 85 years	Decision to be screened should be based on a person’s preference, life expectancy, overall health, and prior screening history.
	>85 years	No screening

The American Cancer Society does not provide recommendations for high-risk individuals. But the same has been offered by the US Multi-Society Task-Force for Colorectal Cancer-

Personal or family history	Recommendations
Persons with 1 first-degree relative with CRC or a documented advanced adenoma diagnosed at age <60 years or with 2 first-degree relatives with CRC and/or documented advanced adenomas	Colonoscopy every 5 years beginning 10 years younger than the age at which the youngest first-degree relative was diagnosed or age 40, whichever is earlier.
Persons with 1 first-degree relative diagnosed with CRC or a documented advanced adenoma at age >60 years	Begin screening at age 40. Same screening intervals as average risk people.
Persons with 1 or more first-degree relatives with a documented advanced serrated lesion (SSP or traditional serrated adenoma >10 min in size or an SSP with cytologic dysplasia)	Colonoscopy every 5 years beginning 10 years younger than the age at which the youngest first-degree relative was diagnosed or age 40, whichever is earlier.

Prostate Cancer:

Digital rectal examination (DRE)
Prostate-specific antigen (PSA) test

A prostate cancer gene 3 (PCA3) RNA test may be used for certain patients. The PCA 3 gene assay was approved by the U.S. Food and Drug Administration in early 2021, with the intended use to aid in the decision for repeat biopsy in men with a previously negative biopsy for an elevated PSA and for whom a repeat biopsy is being considered for a persistently elevated PSA. This test is performed on a urine sample collected after an attentive digital rectal examination(DRE) - several strokes applied firmly to the prostate to the right and left prostatic lobes. Using a threshold value of 60, this test enhances the detection of prostate cancer while reducing the number of biopsies in men who are expected to ultimately have a negative biopsy.

According to the USPSTF, for men aged 55 to 69 years, the decision to undergo periodic prostate-specific antigen (PSA) - based screening for prostate cancer should be an individual one. It also recommends against PSA-based screening for prostate cancer in men 70 years and older.

The Memorial Sloan Kettering prostate cancer screening guidelines state that men aged 45-70 should have their PSA levels checked. Testing for men between 71-75 years of age should be based on past PSA levels and the health of the man. These guidelines do not recommend testing for men ages 76 or older.

Lung Cancer:

Low-dose computed tomography (LDCT)

The USPSTF recommends annual screening for lung cancer with low-dose computed tomography (LDCT) in adults aged 55 to 80 years who have a 30 pack-year smoking history and currently smoke or have quit within the past 15 years. Screening should be discontinued once a person has not smoked for 15 years or develops a health problem that substantially limits life expectancy or the ability or willingness to have curative lung surgery.

In 2021, the American College of Chest Physicians, the American Society of Clinical Oncology, and the American Thoracic Society recommended screening for lung cancer with LDCT, for persons aged 55 to 74 years who have a ≥30 pack-year smoking history and currently smoke or have quit in the past 15 years.

The American Association for Thoracic Surgery recommends annual screening with LDCT in current and former smokers aged 55 to 79 years who have a 30 pack-year smoking history. It also recommends annual screening starting at age 50- to 70 years in patients who have a 20 pack-year smoking history and additional comorbid conditions that produce a cumulative risk for cancer of at least 5% over the next 5 years. Furthermore, it recommends annual screening in long-term cancer survivors aged 55 to 79 years.

In 2013, the American Cancer Society also began recommending screening for lung cancer with LDCT in high-risk patients who are in relatively good health and meet the following criteria - persons aged 66 to 74 years who have a ≥30 pack-year smoking history and currently smoke or have quit in the past 15 years.

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References:

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3. World Health Organization (WHO). WHO position paper on Mammography Screening [Internet]. 2014 [cited 2021 Feb 2].Available from: https://www.who.int/cancer/publications/mammography_screening/en/

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https://www.cancer.net/cancer-types/cervical-cancer/screening-and-prevention

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risk: 2020 guideline update from the American Cancer Society. CA Cancer J Clin. 2020 Sep;70(5):321-46.

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https://www.cancer.gov/types/colorectal/patient/colorectal-screening-pdq

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10. Prostate Cancer Screening (PDQ@®)}Health Professional Version [Internet]. National Cancer Institute. 2019 [cited 2020 Feb 2].

Available from: https://www.cancer.gov/types/prostate/hp/prostate-screening-pdq

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12. Prostate Cancer Screening Guidelines | Memorial Sloan Kettering Cancer Center [Internet]. [cited 2020 Feb 2]. Available from:

https://www.mskcc.org/cancer-care/types/prostate/screening/screening-guidelines-prostate

13. Final Recommendation Statement: Lung Cancer: Screening - US Preventive Services Task Force [Internet]. [cited 2020 Feb 2].

Available from: https://www.uspreventiveservicestaskforce.org/Page/Document/RecommendationStatementFinal/lung-cancer-screening

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