By Eduardo Gonzales, MD
Are there tests that can detect whether you have cancer or not? Can you write about these tests? —firstname.lastname@example.org
Tests that check your body for cancer before you get symptoms are called cancer screening test, and there is a wide array of it. It include physical examination; laboratory tests that utilize blood, urine, or other tissues as samples; imaging procedures such as x-ray exams, MRI, and CT scans; and genetic tests that look for certain gene mutations that are linked to some types of cancer.
Pros and cons of cancer screening tests
Screening tests are potentially very helpful because, as a rule, when cancer is detected early, it is easier to treat and, in certain instances, even cure; while if abnormal changes that invariably result in cancer are found, cancer can be prevented.
Not all forms of cancer, however, have screening tests. Furthermore, many screening tests are not routinely recommended for a variety of reasons. For one, most are not innocuous. Many carry significant risks, for example, colonoscopy to screen for colon cancer can perforate the colon. Also, screening tests can give false positive results—they say there is cancer when there is none. Conversely, false negative results also occur (tests yield normal results when in fact there is cancer).
Likewise, for some cancers, finding and treating the disease early does not improve the chances of a cure or life expectancy. This is true for cancers of the ovary, prostate, and skin. Often, in these forms of cancer, treatment only unnecessarily exposes patients to the side effects of surgery, radiotherapy, chemotherapy, and other treatment modalities, which can be extremely uncomfortable and even debilitating.
Cancer screening tests that are worth taking
Of the numerous cancer screening tests available, the only ones the American Cancer Society (ACS) recommends to be performed routinely are those that are for breast, colorectal, cervical, and endometrial cancers. In addition, lung cancer screening is recommended for some people who are at high risk.
Screening for breast cancer
The salient features of the ACS guidelines for breast cancer screening are as follows: Women ages 40 to 44 should have the choice to start annual breast cancer screening with mammograms (x-rays of the breast) if they wish to do so, while women age 45 to 54 should get mammograms every year. Women 55 and older, on the other hand, should switch to mammograms every two years, or can continue yearly screening.
Screening for colorectal cancer and polyps
For colorectal cancer and polyps, ACS says all people starting at age 50 should undergo one (only one) of the following screening procedures: flexible sigmoidoscopy every five years, or colonoscopy every 10 years, or double-contrast barium enema every five years, or CT colonography (virtual colonoscopy) every five years, or yearly guaiac-based fecal occult blood test (gFOBT), or yearly fecal immunochemical test (FIT), or stool DNA test (sDNA) every three years.
Screening for cervical cancer
For cervical cancer, the ACS recommends testing for women starting at age 21. The screening procedures and their frequency vary per age group and can consist of Pap test and, in some instances, an HPV test.
All women who have been vaccinated against HPV should still follow the screening recommendations for their age groups.
Endometrial (uterine)cancer screening
The essence of the ACS recommendation on endometrial cancer screening is that menopausal women should report any unexpected vaginal bleeding or spotting to their doctors while some women—because of their history—may need to consider having a yearly endometrial biopsy.
Lung cancer screening
The ACS recommends an annual low-dose CT scan (LDCT) of the chest for people 55 to 70 years of age who are in good health but at high risk of lung cancer due to cigarette smoking. People who are at high risk are those who have at least a 30 pack-year smoking history and are either still smoking or have quit within the last 15 years (a pack-year is the number of cigarette packs smoked each day multiplied by the number of years a person has smoked).