Can dogs know about cancer in people?

Can dogs know about cancer in people? Research has shown that dogs can detect many types of cancer in humans. Like many other diseases, cancer leaves specific traces or odor signatures in the body and body secretions. Cancer cells or healthy cells affected by cancer produce and release these odor signatures. Depending on the type of cancer, dogs are able to detect different smells from human skin, breath, urine, feces, and sweat. Dogs can detect these odor characteristics and by alerting people to the presence of their physical problems. However, not all dog breeds can smell these different odors, and only trained medical detection dogs can do so.