How do doctors test for cancer?

Issue
I was wondering if they can tall if someone has cancer from blood tests.

Best Tip

Yes, some forms of cancer can be detected by blood tests.

Others
Well sometimes they see something abnormal in the blood and then they will do a certain test to see what it is, and then they can do a full body scan to see where it is......so yes.
Detection
Direct or assisted visual observation is the most widely available examination for the detection of cancer. It is useful in identifying suspicious lesions in the skin, retina, lip, mouth, larynx, external genitalia, and cervix.

The second most available detection procedure is palpation to detect lumps, nodules, or tumors in the breast, mouth, salivary glands, thyroid, subcutaneous tissues, anus, rectum, prostate, testes, ovaries, and uterus and enlarged lymph nodes in the neck, axilla, or groin.

Internal cancers require procedures and tests such as endoscopy, x-rays, magnetic resonance imaging, or ultrasound. Laboratory tests, such as the Pap smear or the fecal occult blood test have been employed for detection of specific cancers.

The performance of screening tests is usually measured in terms of sensitivity, specificity, and positive-predictive values (PPV) and negative-predictive values (NPV). Sensitivity is the chance that a person with cancer has a positive test. Specificity is the chance a person without cancer has a negative test. PPV is the chance that a person with a positive test has cancer. NPV is the chance that a person with a negative test does not have cancer. PPV and, to a lesser degree, NPV are affected by the prevalence of disease in the screened population. For a given sensitivity and specificity, the higher the prevalence, the higher the PPV.

http://www.cancer.gov/cancerinfo/pdq/scr...

Peace.
No, not always.
Most cancers are initially recognized either because signs or symptoms appear or through screening. Neither of these lead to a definitive diagnosis, which usually requires the opinion of a pathologist.

Roughly, cancer symptoms can be divided into three groups:

1. Local symptoms: unusual lumps or swelling (tumor), hemorrhage (bleeding), pain and/or ulceration. Compression of surrounding tissues may cause symptoms such as jaundice.
2. Symptoms of metastasis (spreading): enlarged lymph nodes, cough and hemoptysis, hepatomegaly (enlarged liver), bone pain, fracture of affected bones and neurological symptoms. Although advanced cancer may cause pain, it is often not the first symptom.
3. Systemic symptoms: weight loss, poor appetite and cachexia (wasting), excessive sweating (night sweats), anemia and specific paraneoplastic phenomena, i.e. specific conditions that are due to an active cancer, such as thrombosis or hormonal changes.
Every single item in the above list can be caused by a variety of conditions (a list of which is referred to as the differential diagnosis). Cancer may be a common or uncommon cause of each item

Blood test results may give a doubt in case of some cancers but it is not the ultimate test.
To my knowledge blood test can detect certain forme of cancer, leukimia, liver etc.
Otherwise, byopsie of the parts concern can reveal if there is cancer.
Depends on the cancer. My husband had testicular cancer, and it elevates something in your blood(can't remember the name right now). They also did a PET scan. If they know what they're looking for, there's more options.