Colon cancer is a disease in which malignant cells form in the tissues of the colon (the longest part of the large intestine). Most colon cancers are adenocarcinomas, or cancers that begin in cells that make and release mucus and other fluids.
Rectal cancer forms in the tissues of the rectum (the last several inches of the large intenstine closest to the anus).
Together, the diseases are called colorectal cancers. Experts believe that the majority of colorectal cancers develop in polyps known as adenomas. Some of these polyps can become tumors.
Our patients with colorectal cancer are treated at our Gastrointestinal Cancer Unit. See the Gastrointestinal Cancer Unit for more information.
You can also review the tabs at the top of this page for information on colorectal cancer symptoms and risks, diagnosis, and treatment.
Video: A Patient's Story
Kay Mueller was 50 when a routine colonoscopy revealed Stage 3 rectal cancer. Follow Kay through treatment at UC San Diego during this video.
Video: Colorectal Cancer Screening and Colonoscopy
Tom Savides, MD, talks with David Granet, MD on UCSD-TV about screening for colorectal cancer, when to start screening, the various tests available and what to expect.
Symptoms of colorectal cancer include:
- Bleeding from the rectum or blood in the stool or toilet after a bowel movement
- Diarrhea, constipation, or feeling the bowel does not empty completely
- Stools that are narrower than usual
- Cramping pain, bloating, fullness or gas
- Fatigue or other non-specific conditions such as weakness, vomiting or shortness of breath
- Age (over 50)
- Family history of colorectal cancer
- Personal history of cancer of the colon, rectum, ovary, endometrium or breast
- Personal history of colon polyps
- Personal history of ulcerative colitis
- Certain hereditary conditions
Diets high in fat may predispose people to colorectal cancer, while diets high in vegetables and high-fiber foods could reduce the incidence of cancer.
An individual’s genetic background is also an important factor in colon cancer risk. Genetic counseling and testing is offered at the Moores UCSD Cancer Center for appropriate candidates by specially trained counselors.
A screening colonoscopy is a procedure to look inside the rectum and colon for polyps, abnormal areas, or cancer. A thin, lighted tube is inserted through the rectum into the colon while the patient is sedated. If polyps are found, samples may be taken for biopsy.
Physicians recommend that individuals with no family history have a colonoscopy at age 50, with no repeat procedure needed for another 10 years if the test is normal. If there are polyps or other abnormalities, the screening should be repeated in three to five years. Patients with a previous diagnosis of colorectal cancer should have a colonoscopy one year after their first episode. If normal, they may be able to wait another three to five years before another colonoscopy.
A digital rectal exam should be done at the same time. These tests offer the best opportunity to detect colorectal cancer at an early stage when successful treatemnt is likely.
Begin colorectal cancer screening earlier and/or more often if you have a personal history of colorectal cancer or adenomatous polyps, a strong family history of colorectal cancer of polyps, a persoanl history of chronic inflammatory bowel disease, or family history of hereditary colorectal cancer syndromes.
UC San Diego Health takes an aggressive approach to benign polyps before they can become malignant. Rather than waiting until a polyp becomes so large that a bowel resection (removal of a portion of bowel) is needed, surgeons remove smaller, benign polyps through a laparoscope inside the colonoscope. Called a lap-assisted endoscopic polypectomy, the procedure by the gastroenterologist and surgeon alleviates risk of bowel damage.
The most effective method of colorectal diagnosis is with a colonoscopy, which involves inserting a thin, lighted tube called a colonoscope into the rectum to visualize the rectum and colon for polyps or masses. If polyps are found, samples may be taken for biopsy, diagnosis and determination of treatment.
An endoscopic ultrasound is used to stage rectal cancers, so your doctor can determine how deep into the rectal wall the tumor invades and if there are any malignant appearing lymph nodes. This is important in guiding the type of therapy, such as whether it can be removed with surgery alone or if chemotherapy and radiation are needed before surgical removal.
Your doctor may also obtain blood tests during the initial diagnosis, and X-rays or CT scans, to determine if the cancer has spread beyond the colon or rectum.
Staging is a process that determines how widespread your cancer may be. Your treatment and outlook largely depends on the stage of your cancer at diagnosis. Because many patients don’t understand where they fall in staging categories, we’ll explain your specific circumstances and what it means in terms of your treatment and outcome.
According to the National Cancer Institute, the stages of colorectal cancer are:
- Stage 0: The cancer is found only in the innermost lining of the colon or rectum. Carcinoma in situ is another name for Stage 0 colorectal cancer.
- Stage I: The tumor has grown into the inner wall of the colon or rectum. The tumor has not grown through the wall.
- Stage II: The tumor extends more deeply into or through the wall of the colon or rectum. It may have invaded nearby tissue, but cancer cells have not spread to the lymph nodes.
- Stage III: The cancer has spread to nearby lymph nodes, but not to other parts of the body.
- Stage IV: The cancer has spread to other parts of the body, such as the liver or lungs.
Recurrence: This is cancer that has been treated and returned after a period of time when the cancer could not be detected. The disease may return in the colon or rectum, or in another part of the body.
Colon cancer treatments
At UCSD, we employ a comprehensive approach to the treatment of colon cancer with integrated use of surgery, radiation when applicable and chemotherapy. This comprehensive approach, along with the most advanced treatment options, provides the patient with the best chance to fight this disease.
See also Colorectal Cancer Unique Treatment Options.
Surgery: This is the most common treatment for colon cancer. Sometimes all the patient needs is a polypectomy – the removal of a polyp – or a local excision, where a small amount of tissue is taken from the colon. If the tumor has invaded the bowel wall or surrounding tissues, a resection, or removal of the cancer and portion of the bowel, may be required. In most cases, the surgeon is often able to reconnect the remaining portions of the colon. In rare cases, the patient will need a temporary colostomy, which is an opening in the abdominal wall to allow passage of stool.
Even if your cancer has spread beyond the colon or rectum, UCSD’s surgical oncologists may still be able to provide a cure. Cancers that have entered the liver, lung and abdominal cavity may sometimes be removed or ablated (burned using radiofrequency energy). Liver surgery can even be performed using laparoscopy, a surgical technique that allows for smaller incisions and quicker recovery. Tumors in the abdominal cavity may also be treated using heated intraperitoneal chemotherapy, a highly effective procedure used only at UCSD and a handful of top cancer centers in the U.S.
Radiation (radiotherapy using photons or electrons): This treatment is not used very often, unless the cancer is recurrent and causing a problem in the pelvis. On the other hand, chemotherapy is required when the colon cancer has spread into the lymph nodes or elsewhere in the body. The most common place for colon cancer to spread is the liver.
Chemotherapeutics: UCSD has been at the forefront in developing new, advanced chemotherapeutics to directly kill tumor cells, choke off the blood supply to the tumors and awake the immune response to combat this cancer. We have a variety of clinical trials for patients with newly diagnosed colon cancer and for patients who have failed other treatments.
Rectal cancer treatments
A Patient's Story
Kay Mueller was 50 years old when a colonoscopy revealed Stage 3 rectal cancer. Watch a video of her story, and see how UC San Diego treated her cancer.
Depending upon the stage of rectal cancer, patients may be given chemotherapy and radiation either before or after surgery. In some cases, the tumor is located so low down in the rectum that surgeons can remove it through the anus without having to perform a major abdominal procedure. When surgery is needed, UCSD utilizes a minimally invasive procedure with the da Vinci robot, which provides less trauma to the body and a faster patient recovery time.
For both colon and rectal cancer, the use of chemotherapy after surgery can increase the survival rate for patients with some stages of colorectal cancer. This is called adjuvant (additional) therapy with drugs.
A treatment called heated intraperitoneal chemotherapy, or HIPEC, is available only at a few medical centers, including here at UC San Diego. (Learn more about HIPEC.) Regional chemotherapy involves injection of drugs directly into an artery leading to the part of the body with the tumor. Among the most commonly used drugs for colon cancer is Fluorouracil (5-FU), which may be given with Leucovorin. Additional chemotherapy drug are Capecitabine (Xeloda), Irinotecan (Camptosar) and Oxaliplatin (Eloxatin). Ask your doctor which therapy is best for your specific cancer.