Early Detection of Cancer

Early Detection of Cancer

The early detection of cancer is the best treatment strategy. It is far preferable to find a cancer and remove it at an early stage rather than later after it has had a chance to grow and spread elsewhere in the body. Almost all cancers are potentially curable if found early enough. The basis for cancer screening is to check for the most common cancers at an age when they are likely to begin to form. Not all cancers have a screening test to check for them. Public health policies have been made to combine cost efficiency and test accuracy while targeting the commonest cancers. This strategy saves lives and saves the cost of treating higher stage cancers which often only provides a modest benefit to life-years saved, sometimes even by just a few months. It is difficult to think of cancer treatment in this way, but when dealing with a finite amount of resources it becomes necessary.

The screening of cancer is focused on the most common cancers. The most common cancers among adults in the United States are:

These are the commonest cancers overall but the list of most common causes of death from cancer is a bit different:

  • Lung cancer (by far the number one cancer killer)
  • Breast Cancer
  • Prostate Cancer
  • Pancreatic Cancer
  • Ovarian Cancer

For some cancers, such as ovarian cancer notably, there is not a readily available and accurate screening test for cancer. This type of cancer is a “silent killer” because it can grow undetected with few symptoms and may not come to the attention of the person until it is far spread making treatment difficult and cure very unlikely. Another example of this would be pancreatic cancer. Most cancers of the pancreas have spread outside of the pancreas to neighboring lymph nodes or even beyond at the time of diagnosis. This is why the prognosis of pancreatic cancer has not changed much in over thirty years.

For some cancers, screening must be targeted to high risk populations. An example of this is screening for lung cancer. Lung cancer is the number one cancer killer and it makes sense to direct efforts to reduce this. A CT scan of the chest is quite accurate in detecting lung cancer but is associated with some risks and drawbacks. A CT scan gives a person a very high dose of radiation that in itself raises the risk of future cancers and also often involves IV dye that can cause serious allergy or even severe kidney damage. A CT scan of the chest is also quite costly. This type of screening test would not be very efficient for the entire adult population, but someone at high risk such as a very heavy smoker for many years may be a good candidate.

Most screening tests target the entire population and try to reduce the morbidity associated with the most common cancers overall; breast cancer, colon cancer and prostate cancer.

Breast Cancer: The current screening guidelines recommend beginning annual mammograms at the age of 40. There are circumstances where screening might begin earlier than this such as if a woman has a sister or mother that was diagnosed with breast cancer at the age of 38 or 39. Mammograms are not as reliable in younger woman because the breast density of young women is higher making interpretation of mammography more difficult. The only drawback of more aggressive screening is that there is a tendency to detect findings that are not cancer but simulate it. This would be referred to as a false positive.

Screening has led to an increased rate of diagnosis of pre-invasive cancer. The overall conclusion from studies on mammography says that it does decrease mortality when done between the ages of 40-70 in women. The test is relatively inexpensive and fairly accurate. There is some discomfort that women frequently complain of with it however.

Colon Cancer: Screening for colon cancer should begin at the age of 50 years. There are a number of options for colon cancer screening. As with breast cancer, there are several situations where screening should begin earlier in a more aggressive fashion. If there is a strong history of colon cancer, early onset cancer, or known polyposis syndrome these people should have screening before the age of 50 sometimes as early as 20.

The most common schedule for colon cancer screening is a colonoscopy every ten years and either fecal occult blood test annually or/and sigmoidoscopy every 3-5 years in between. None of these tests are 100% accurate (as no test is) but they do a reasonable job at screening for cancer. Checking for blood in stool is based upon the likelihood that most cancers of the intestine cause a bit of bleeding. Up to 30% of colon cancers may not cause blood in the stool and there is a chance that a cancer might not be bleeding when the test was performed. Similarly, colonoscopy may miss about 10-30% of small polyps and around 5-10% of polyps that contain cancer. Despite these limitations, these tests to save lives and do a good job at detecting early cancers when they are quite treatable.

Cervical cancer screening should begin soon after a woman becomes sexually active and generally by the age of 20. The Pap smear test is also a very accurate test for detecting cervical cancer or more commonly pre-cancer type lesions. Screening for infection with HPV (human papilloma virus) is also important, since almost all cervical cancer is thought to be caused by HPV infection.

Prostate cancer screening generally begins around the age of 50 and combines both digital rectal examinations with blood measurement of a PSA level. At the current time, there is a lot of research and debate about the usefulness of PSA screening.

A discussion with your doctor about your personal risk factors and family history of cancer will help you to make informed decisions about cancer screening and guide any possible modifications to the standard screening guidelines.


  1. www.cancer.gov/cancertopics/screening
  2. apps.nccd.cdc.gov/uscs/toptencancers.aspx#All
  3. Carey WD. (2010) Cleveland Clinic: Current Clinical Medicine, 2nd ed. Section 14. Cleveland, OH: Saunders
  4. www.cancer.org/Cancer/CancerBasics/cancer-prevalence
  5. This article was originally published on September 3, 2012 and last revision and update was 9/4/2015.