How do I know if colon cancer has spread in my body?

See a doctor. Numerous test including ct scans and pet scans can determine if there is any evidence for metastatic disease. See your oncologist for the best advice.
Difficult to know. You may have pain in the belly or weight loss. Usually we know about cancer spread by looking at the lymph nodes removed with surgery. We also look at ct scans before surgery to examine the liver and the lungs. Ct scans and sometimes a blood test for CEA can help look for spread after surgery for colon cancer.

Related Questions

How can colon cancer affect the body?

Blockage/Bleeding. Depending on their size and location, colon cancers may cause the above problems. The bleeding tends to be very slow, like a dripping faucet, and may not be evident by sight. Obstruction can cause a change in bowel habits (constipation, pencil-thin stools) and/or bloating. Like any cancer, there is the potential to spread to other organs, which may cause fatigue, loss of appetite, wt loss, etc.
Colon Cancer Symptom. The symptoms vary in severity and may start slowly or suddenly. Symptoms include: abdominal pain and cramping that usually disappears after a bowel movement, abdominal sounds, weight loss, diarrhea, blood or pus in the stools, and rectal pain. If you had ulcerative colitis as an antecedent condition, you may experience joint and skin symptoms, fever, and other exa intestinal manifestations.

What does colon cancer do to my body?

Many things. Untreated colon cancer can cause bleeding and anemia, weight loss, diarrhea or constipoation or complete blockage of your bowels, pain, eventually metastatic to liver, lung and bone and ultimately death.
Depends... I like dr. Kaplan's answer but want to add that colon cancer may be silent until it's too late. Screening is very important therefore.

How does colon cancer affect the body?

Depends. Early on there may be no effect. As the disease progresses undiagnosed, you may develop a change in bowels, blood in stool, abdominal pain, weight loss, loss of appetite, lethargy, loss of stamina, bowel obstruction, shortness of breath, anemia, early diagnosis in high risk patients or regular colonoscopies is the best way to avoid all of the above.
Bleeding. In early phase it will cause change in bowel movement, bleeding from the gastrointestinal tract. Later, it may cause obstruction due to stricture. Eventually, the cancer spread and takes on the general well being of the host and kills the patient.
Lots of changes. Colon cancer can lead to pain, abdominal swelling, bloating, bloody stools, spread to other organs and eventually death if left untreated. Fortunately we have many effective therapies for patients with colon cancer.

Is endometriosis that spread to or in the colon considered regular colon cancer?

No. Colon cancer usually starts in the inner part of the colon. Endometriosis implants on the colon, but is not invasive or life threatening.