DEAR MAYO CLINIC: After my brother was diagnosed with colorectal cancer, I read that it's often treated with surgery first. Can you tell me more about the surgery?

ANSWER: When someone is diagnosed with colorectal cancer — which includes both colon and rectal cancers— many people immediately think "surgery." And it’s true that surgery plays a central role in treatment for most patients. But whether it comes first, and what it entails, depends on several factors, especially where the cancer is located, how far it has grown into surrounding tissues, and whether it has spread.

For colon cancer, surgery is typically the first and main step when the disease hasn't spread to distant organs. The goal is to remove the cancerous part of the colon along with nearby lymph nodes, which are the first places cancer spreads. After surgery, the removed tissue is examined under a microscope to confirm the stage of the disease and decide whether additional treatment, such as chemotherapy, is needed.

In early-stage colon cancer (stages 1and 2), surgery alone may be curative. Many patients won't need further treatment beyond regular follow-ups. In stage 3 disease, chemotherapy after surgery is usually recommended to help reduce the risk of the cancer returning.

Surgery also may be used in more advanced cases, including relieving symptoms like bleeding or bowel obstruction, or removing tumors in other organs, which might help control the disease.

Rectal cancer, found in the last several inches of the large intestine, is often treated differently from colon cancer. Because the rectum is deep in the pelvis next to other organs and structures, such as nerves that control bowel and bladder function, doctors often use a multidisciplinary approach.

For many rectal cancers, especially those that are locally advanced or close to critical structures, treatment typically begins with chemotherapy and radiation before surgery. The aim is to shrink the tumor so it can be removed more completely and safely and reduce the risk that it will come back.

This sequence, called neoadjuvant therapy, is less common in colon cancer but standard in many cases of rectal cancer, which have a higher risk of local recurrence. It often improves outcomes and, in some carefully selected patients, may even allow preservation of more typical bowel function.

Rectal cancer care can involve a team of specialists, including colorectal surgeons, medical oncologists and radiation oncologists, who discuss each case together to tailor the best plan for each patient.

Goal of surgery

Whether it's for colon or rectal cancer, the basic aim of surgery is the same: to remove the tumor completely, along with a margin of healthy tissue around it and nearby lymph nodes. The surgeon then reconnects the remaining bowel so it can continue normal function.

Many colorectal operations are performed using minimally invasive techniques such as laparoscopy or robotic-assisted surgery. These methods use small incisions and advanced instruments that allow surgeons to work precisely, leading to fewer complications, less pain and a faster recovery than with traditional open surgery.

For colon cancer, minimally invasive colectomies are common and, in many patients, can be done through several very small incisions. Recovery may be quicker, with patients beginning to eat soon after surgery and returning home in a few days.

For rectal cancer, minimally invasive techniques also are used, but the surgery can be more complex because of the tighter space in the pelvis and the need to preserve nerves. Robotic surgery in particular offers 3D visualization and refined control that can be especially helpful.

Surgery for rectal cancer can sometimes affect bowel function. In some patients, a temporary or permanent stoma, an opening on the abdomen for waste to pass, may be necessary depending on the tumor's location and extent.

Even with technically successful surgery, some patients experience changes in bowel habits or control (a condition sometimes called low anterior resection syndrome), urinary difficulties or sexual dysfunction. These are important aspects to discuss with your care team.

Approaches to treating colorectal cancer

Not every colorectal cancer case is the same. The approach is individualized based on:

Stage of the cancer: how deep it has penetrated and whether it has spread.

Location of the tumor: rectal cancer often needs a different sequence of therapy than colon cancer.

Overall health and preferences: patient goals, other medical conditions and recovery expectations all matter.

Experience matters when it comes to optimizing outcomes in patients with colorectal cancer. That's why it's important to seek care from expert centers that treat a high volume of patients with colorectal cancer each year, use multidisciplinary teams to review each case, and recommend a therapeutic sequence that balances cure and quality of life.

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Eric Dozois, M.D., Colon and Rectal Surgery, Mayo Clinic, Rochester, Minnesota

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