Colon Cancer

Introduction

Cancer of the colon and rectum (or colorectal cancer) is the third most common form of cancer and is the second leading cause of cancer mortality in the United States.
Advanced colorectal cancer means that the cancer has spread to other parts of the body from where it started in the bowel (colon) or back passage (rectum). Your cancer may be advanced when it is first diagnosed. Or the cancer may come back some time after you were first treated. When cancer comes back after treatment it is called recurrent cancer.

Symptoms and Diagnosis

Screening measures used to detect early cancers or premalignant polyps in asymptomatic persons include digital rectal examination, fecal occult blood testing, endoscopy and radio-graphic imaging, Colon cancer may be asymptomatic. When present symptoms may include anemia, rectal bleeding and change in bowel habits  (painful incomplete fecal evacuation) depending on the location and extent of the tumor. Systemic manifestations such as weight loss and fatigue due to chronic anemia suggest advanced disease. Obstruction, perforation, and acute bleeding may occur as complications of colon cancer.

Physical examination may reveal a palpable abdominal or rectal mass. Abdominal distention suggests high-grade rectal or colonic obstruction, and rarely the presence of malignant ascites.

The entire colon should be examined preoperative by colonoscopy or barium enema if cancer of the colon or rectum is suspected, unless contraindicated by colonic obstruction or other circumstances. With colonoscopy, cancers can be seen and biopsied, and synchronous neoplastic polyps can be removed if not contained within the segment of resected bowel.

Treatment options by stage

Stage 0 colorectal cancer

The usual treatment is a polypectomy (removal of a polyp) during a colonoscopy. There is no additional surgery unless the polyp cannot be fully removed.

Stage I colorectal cancer

Surgical removal of the tumor and lymph nodes is usually the only treatment needed.

Stage II colorectal cancer

Patients should talk with their doctor about whether more treatment is needed after surgery, as some patients receive adjuvant chemotherapy. This is treatment after surgery with chemotherapy aimed at trying to destroy any remaining cancer cells. However, cure rates for surgery alone are quite good, and there are few benefits of additional treatment for people with this stage of colon cancer. Learn more about adjuvant therapy for stage II colorectal cancer. A clinical trial is also an option after surgery.

For patients with rectal cancer, radiation therapy is usually given in combination with chemotherapy, either before or after surgery.

Stage III colorectal cancer

Treatment usually involves surgical removal of the tumor followed by adjuvant chemotherapy. A clinical trial is also an option. For patients with rectal cancer, radiation therapy may be used along with chemotherapy before or after surgery.

Metastatic (stage IV) colorectal cancer

If cancer has spread to another location in the body, it is called metastatic cancer. Colorectal cancer can spread to distant organs, such as the liver, lungs, peritoneum (the tissue lining the abdomen), or a woman's ovaries.

Patients with this diagnosis are encouraged to talk with doctors who are experienced in treating this stage of cancer, because there can be different opinions about the best treatment plan. Learn more about seeking a second opinion before starting treatment, so you are comfortable with the treatment plan chosen. This discussion may include clinical trials.


Risks

Postoperative complications of resection for colorectal cancer generally involve infections related to the bacterial flora of the large bowel. The most common postoperative complication is wound infection (2-4% in elective cases), which is minimized by mechanical and antibiotic bowel preparation and prophylactic intravenous antibiotics. Other risks include bleeding, anastomotic leakage, pelvic abscess, damage to neighboring organs (such as the spleen or ureter), sexual and urinary dysfunction.

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