A cancer patient holds the IV tubes during chemotherapy.
Cancer: The facts
01:00 - Source: CNN
CNN  — 

Testing for cancer in blood, urine or even saliva: That approach has been called the “holy grail” for diagnosing the second leading cause of death in the world, and it has been fueling an area of research that continues to raise eyebrows and questions.

Doctors can diagnosis cancers in a number of ways, including taking biopsies of tissue where a suspected tumor might be; imaging tests such as X-rays, ultrasounds or MRIs; and screening tests such as endoscopies or colonoscopies.

Yet some of those approaches can be uncomfortable for patients or may come with hefty medical bills, among other potential downsides.

For the future, many cancer researchers are exploring whether a cancer test could involve only collecting and analyzing a sample of your blood, saliva or urine so that it’s noninvasive, cheaper and more appealing to patients – especially when trying to diagnose cancer early.

These bodily fluids or liquid biopsies “have the potential to help clinicians screen for disease, stratify patients to the best treatment, and monitor treatment response and development of resistance,” the American Association for Cancer Research says.