Dr. Lee was born in Shanghai, China, and received his college and medical training in the United States. He is fluent in English and three Chinese dialects. He graduated with chemistry departmental honors from Harvey Mudd College. He was appointed president of AOA society at UCLA School of Medicine. He underwent internal medicine residency and gastroenterology fellowship training at Cedars Sinai Medical Center.
Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.
The colon, also
known as the large intestine or large bowel, constitutes the last part of the digestive tract. The colon is a long, muscular tube that receives undigested food from the small intestine. It removes water from the undigested food, stores it and then finally eliminates it from the body through bowel movements.
The rectum is the last part of the colon adjacent to the
Cancer of the colon and rectum (colorectal cancer)
malignant tumor arising from the inner wall of the large intestine. These malignant tumors invade nearby tissue and spread to other parts of the
body. Benign tumors
of the colon are called polyps. Benign polyps do not invade
tissue or spread to other parts of the body like malignant tumors do. Benign polyps can
easily during colonoscopy and are not life threatening.
benign polyps are not removed from the large intestine, they
malignant (cancerous) over time. In fact, most of the cancers
of the large
intestine are believed to have evolved from benign
polyps that are pre-cancerous, that is, they are benign at first but later become cancerous.
Cancer of the colon and rectum invades and damages adjacent tissues
organs. Cancer cells also can break away and spread to other
parts of the
body (such as the liver and lung) where new tumors grow. The sprocess
cancer preads to distant organs is called metastasis, and the new tumors are called metastases.
Once metastasis has occurred in colorectal cancer, a complete
cure of the
cancer is unlikely.
Colorectal cancer is both preventable and curable. Colorectal
prevented by removing precancerous colon polyps
. It is cured if it is found early
and is surgically
removed before it spreads to other parts of the
body. The National
Polyp Study showed in its surveillance program that individuals who
their polyps removed experienced a 90% reduction in the incidence of
The few patients in the study who did develop colorectal cancer had their
cancer discovered at
early, surgically or endoscopically curable stages. Since most colon polyps
early cancers are silent (produce no symptoms), it is important to do screening and surveillance for colon cancer
without symptoms or signs of the polyps or cancers. Recommendations
cost-effective public screening and surveillance have been
endorsed by numerous societies including the American Cancer
National Cancer Institute, American College of
Medical Association, American College of Physicians, etc.
Symptoms of colorectal cancer are numerous and nonspecific. They include fatigue, weakness, shortness of breath, change in bowel habits, narrow stools, diarrhea or constipation, red or dark blood in stool, weight loss, abdominal pain, cramps, or bloating. Other conditions such as irritable bowel syndrome (spastic colon), ulcerative colitis, Crohn's disease, diverticulosis, and peptic ulcer disease can have symptoms that mimic colorectal cancer.
Doctors often cannot explain why one person develops cancer and another
does not. But research shows that certain risk factors increase the chance
that a person will develop cancer. These are the most common risk f"...