There are a number of recommended screening tests for cancer.
Mammography has been shown quite effective in reducing deaths from breast cancer, it is recommended for women ages 40 to 74.
HPV and PAP tests are recommended for cervical cancer screening in women. Testing should begin at age 21 and end at age 65.
Colonoscopy is recommended for colorectal cancer screening for both men and women ages 45 through 75.
HCT, a type of CT, is recommended for heavy smokers at ages 15 to 80.
Where the risks are high, there are other tests not generally recommended for everybody. Tests are available for liver cancer, prostate cancer, skin cancer, and ovarian cancer where are the risk is high. In women with BRCA1 And BRCA2 mutations, breast MRIs are recommended.
Personally, I get a yearly PSA test, mainly because a good friend, a physician, died within 3 years of prostate cancer when he stopped taking the test.
I also get a skin examination by a dermatologist every six months, because I have a very fair skin, probably caused by the freckle variant of the MC1R gene.
There are a number of symptoms and signs that suggest cancer, particularly when they don’t go away, such as fatigue, weight loss or gain for no apparent reason; trouble swallowing, nausea, or abdominal pain; swelling or lumps anywhere in the body; cough or hoarseness; unusual bleeding; change in bowel habits; fevers or night sweats; bleeding areas in the mouth. Protracted headaches or vision problems can be worrisome.
In short, any distressing or unusual symptom that doesn’t improve on its own should be watched very carefully, and reported to your doctor; but it is far better to pick them up early with a test or a doctors routine examination than to wait for symptoms to develop.