What Is Stage 3 Colon Cancer?

Symptoms, Diagnosis, Treatment, and Prognosis

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Stage 3 colon cancer is when a mass of cells called a tumor spreads (metastasizes) beyond the lining of the colon to nearby lymph nodes—small structures that are part of the immune system. Although the lymph nodes will contain cancer cells, the disease will not yet have spread to distant organs in the body, such as the liver or lungs.

This article reviews the possible symptoms of stage 3 colon cancer and how doctors go about classifying, diagnosing, and treating it. You'll also learn about the expected outcome if you or a loved one are diagnosed with it.

Symptoms of Stage 3 Colon Cancer

While people with stage 1 and stage 2 colon cancer will often have no signs of the disease, those with stage 3 are more likely to develop noticeable symptoms.

This is not always the case, though, and depends largely on the size and location of the tumor.


A tumor within the colon can cause a stricture, which is narrowing of the intestinal passage. Eventually, as the tumor continues to grow, the interior space within the colon may become partially or completely blocked (bowel obstruction).

This narrowing or obstruction of the colon from the tumor can slow or prevent the normal movement of waste, fluids, and gas. As a result, symptoms like abdominal cramping or a change in bowel habits—constipation or diarrhea—may occur.

Bleeding is another potential symptom. You may notice bright red blood in your stool or stool that looks dark brown or black.

Alternatively, your stool may look perfectly normal.

Slow bleeding from the tumor may cause a low red blood cell count (iron deficiency anemia). Anemia can make you feel unusually weak or tired and can be diagnosed with a simple blood test.

Other possible symptoms of stage 3 colon cancer include:

  • Nausea or vomiting
  • Loss of appetite
  • Bloating
  • Unintended weight loss


There are different types of colon cancer. The majority of them are adenocarcinomas, cancers that start in cells that secrete fluids like digestive juices.

The less common types of colon cancer can sometimes manifest with distinct symptoms. Among them:

  • Mucinous adenocarcinoma: A less-common form of adenocarcinoma affecting mucus-producing cells, it is characterized by the abundant secretion of mucus, which will be visible on stools.
  • Gastrointestinal stromal tumors (GIST): These affect cells in the wall of the colon and can sometimes form a hardened mass in the abdomen that can be felt during an exam.
  • Leiomyosarcoma: These affect the smooth muscles of the colon and are more likely to cause tenesmus, the feeling that you need to defecate even when the bowel is empty.

Other rare forms of colon cancer, like signet ring carcinoma and primary melanoma, are more aggressive and can rapidly progress from stage 3 to stage 4 if not detected early.


Symptoms of colon cancer generally result from the tumor growing and blocking the normal flow of stool and gas through the intestines. These symptoms may include abdominal cramping, constipation, or diarrhea. Blood in your stool or unusual tiredness from anemia may also occur.

Colon Cancer Doctor Discussion Guide

Get our printable guide for your next healthcare provider's appointment to help you ask the right questions.

Doctor Discussion Guide Woman


If colon cancer is suspected, your healthcare provider will perform a battery of evaluations and tests, starting with a physical examination and medical history.

The findings of the physical exam are often non-specific but may reveal the following:

  • Abdominal tenderness or swelling
  • Unusually loud or absent bowel sounds
  • A mass that can be felt by pressing on the abdomen
  • Fecal impaction (hard stool that is stuck in the rectum)
  • Significant weight loss
  • Evidence of bleeding from a rectal exam

In addition to the physical exam and asking you about your symptoms, your healthcare provider will ask about your family history of cancer, whether you have been diagnosed with inflammatory bowel disease (IBD), and if you have any other risk factors for colon cancer. Based on these initial findings, other tests may be ordered.

Lab Tests

If you are experiencing possible symptoms of colon cancer, like a change in bowel habits, your doctor may recommend a screening stool test.

However, screening stool tests are not used if you are experiencing suspicious, more specific symptoms like visible blood in your stool or evidence of bleeding on a rectal exam.

Screening tests come with the possibility of a false-negative result, meaning you have colon cancer but the test says you don't. That's why a diagnostic colonoscopy (see below) recommended in these cases instead.

Screening stool tests include:

  • Fecal occult blood test (FOBT), which can check for evidence of blood in a stool sample (restriction of certain foods is necessary ahead of time)
  • Fecal immunochemical testing (FIT), a test similar to the FOBT that does not require a restricted diet
  • Stool DNA test (Cologuard), an at-home test for adults 45 and older that combines the FIT with a test that checks for DNA changes in the stool; you mail your sample to a lab for analysis

Besides stool tests, various blood tests may be ordered during your work-up for possible colon cancer:

  • Complete blood count (CBC) can help detect iron-deficiency anemia caused by bleeding in the colon.
  • Liver function tests (LFTs) can help see whether colon cancer, if present, has metastasized to the liver. However, it is possible for these tests to be normal despite the cancer having spread to this organ.
  • Tumor marker blood tests, like the carcinoembryonic antigen (CEA) test, are used to detect proteins and other substances that are produced in excess when there is cancer. Since it's also possible for these tests to be normal in patients with cancer, they cannot be used alone for screening or diagnosis.

Interestingly, a newer blood-based test called the CellMax liquid biopsy is under active investigation for detecting signs of colon cancer in blood samples. This test has not yet been approved by the U.S. Food and Drug Administration (FDA), so it's not yet commercially available.

Imaging Studies

Imaging scans may be performed to examine areas in the body suspicious for cancer and to see if a cancer, if present, has spread and how far.

Among them:


The most direct method of diagnosis is colonoscopy, an outpatient procedure in which a flexible scope with a special, lighted camera is used to see inside the colon.

Colonoscopy is relatively non-invasive and typically performed under monitored anesthesia. The scope, called a colonoscope, is not only able to navigate the intestinal passageway but can also take photos and obtain tissue samples for examination in the lab.

Most diagnostic colonoscopies can be performed within 30 to 60 minutes, not including preparation and anesthesia recovery time.


A biopsy, or tissue sample, is considered the gold standard for confirming colon cancer, as it's the only way to definitively diagnose the disease.

A biopsy is usually performed during a colonoscopy. In some cases, surgery may be required to perform a biopsy.

To obtain a biopsy during a colonoscopy, special instruments are fed through the tube of the colonoscope to pinch, cut, or electrically remove pieces of tissue. Once obtained, the sample is sent to a doctor called a pathologist.

The pathologist examines the tissue under a microscope to determine whether cancer cells are present. If so, they will begin the process of classifying the cancer—for example, by testing the cancer cells for specific gene changes.


While laboratory or imaging studies may aid in the diagnostic process, a biopsy—obtained through a colonoscopy or surgery—is how doctors confirm the diagnosis of colon cancer.

Staging and Grading

Staging and grading are processes by which the extent and severity of the cancer are determined. These factors help guide the patient's treatment plan and also help predict a patient's prognosis, or likely outcome.

Cancer Staging

The exact stage of the colon cancer characterizes the extent of its progression. The stage is confirmed when the tumor is surgically removed.

A system called the TNM Classification of Malignant Tumors is used to classify the cancer based on three factors (represented by letters) and the extent of each one (represented by numbers).

  • T describes the depth of invasion of the primary (original) tumor.
  • N describes the number of regional (nearby) lymph nodes with cancer.
  • M stands for metastasis and describes whether the cancer has spread to distant organs or not.

Numbers from 0 to as high as 5 are attached to each letter to describe the degree of involvement.

With stage 3 colon cancer, there will be a positive finding of a primary tumor and regionally affected lymph nodes, but no signs of metastasis.

The stage is further broken down into three substages—stage 3A, 3B, and 3C—with each advancing letter representing a progression of the disease.

Stage TNM Stage Description
3A T1-2 N1 M0 Tumor cells in 1 to 3 regional lymph nodes with cancer in either the mucosal or underlying muscle layer
  T1 N2a M0 Tumor cells in 4 to 6 regional lymph nodes with cancer in the mucosal layer
3B T3-4a N1 M0 Tumor cells in 1 to 3 regional lymph nodes with cancer extending just beyond the confines of the colon or in the surrounding peritoneum (abdominal cavity)
  T2-3 N2a M0 Tumor cells in 4 to 6 regional lymph nodes with cancer either in with the muscle layer or extending just beyond the confines of the colon in adjacent tissues
  T1-2 N2b M0 Tumor cells in 7 or more regional lymph nodes with cancer in either the mucosal or underlying muscle layer
3C T4a N2a M0 Tumor cells in 4 to 6 regional lymph nodes with cancer in the peritoneum
  T3-4a N2b M0 Tumor cells in 7 or more regional lymph nodes with cancer extending just beyond the confines of the colon or in the peritoneum
  T4b N1-2 M0 Tumor cells in at least 1 regional lymph node with direct invasion of the tumor into adjacent organs

Tumor Grade

In addition to staging, the tumor will be graded by the pathologist. The grade predicts the likely behavior of a tumor based on how abnormal the cells look.

The grading will involve the use of stains and other techniques to see how different the cancer cells look from normal cells, which is called cell differentiation. These features can usually tell the pathologist how fast or slow the cancer is growing and whether the cancer is more or less likely to spread.

The cancer grades range from G1 to G4, with lower values representing a slower growing tumor that is less likely to spread and higher numbers representing a more aggressive tumor that is more likely to spread.

Grade Classification Cell Differentiation
G1 Low-grade Well-differentiated
G2 Intermediate-grade Moderately-differentiated
G3 High-grade Poorly-differentiated
G4 High-grade Undifferentiated


Stage 3 colon cancer is typically treated with surgery, chemotherapy, and, in some cases, radiation therapy. The treatment plan will often require several medical specialists, including a gastroenterologist, surgical oncologist, medical oncologist, radiation oncologist, and your general physician.

Typically, your medical oncologist oversees and helps coordinate all facets of your cancer care. Your general physician confers with the specialists to manage your overall health. All are essential to your long-term health and well-being.

With treatment, many stage 3 colon cancers can be placed into remission, meaning that the signs and symptoms of cancer will have disappeared—in some cases forever. Even if partial remission is achieved, treatment can slow the progression of the cancer.

With improved therapies and treatment protocols, people with stage 3 colon cancer are living longer than ever.


Stage 3 colon cancer is typically treated with surgical resection, in which a surgeon removes the affected part of the colon. This is called a partial colectomy or subtotal colectomy.

The colectomy may be performed laparoscopically (with tiny "keyhole" incisions and specialized narrow equipment) or with traditional open surgery (when a large incision is made). The cut ends of the intestines are then surgically attached with staples or sutures.

The procedure may be accompanied by a lymphadenectomy, or lymph node dissection, in which nearby lymph nodes are also removed.

The number of lymph nodes removed is based on a number of factors, including how much of the tumor was removed, the location and grade of the tumor, and the age of the patient. Generally speaking, a lymph node dissection is considered adequate when at least 12 lymph nodes are taken out.


Chemotherapy is typically used in adjuvant therapy, meaning that is delivered after surgery to clear any remaining cancer cells.

There are several forms of combination chemotherapy used in people with stage 3 colon cancer:

  • FOLFOX: A combination of 5-FU (fluorouracil), leucovorin, and oxaliplatin delivered by intravenous infusion
  • FLOX: A combination of leucovorin and oxaliplatin delivered by intravenous infusion accompanied by an injection of 5-FU delivered all at once a single (bolus) dose
  • CAPOX: A combination of Xeloda (capecitabine) and oxaliplatin

For advanced stage 3 tumors that cannot be removed completely with surgery, a course of chemotherapy along with radiation may be prescribed before surgery. This type of treatment, referred to as neoadjuvant therapy, can help shrink the tumor so that it is easier to resect.

For people with good performance status, meaning they are able to carry out daily tasks without assistance, the standard course of chemotherapy for stage 3 colon cancer is seven or eight cycles given over six months.

Radiation Therapy

Radiation may sometimes be used as neoadjuvant therapy, typically in tandem with chemotherapy (referred to as chemoradiation therapy).

At other times, radiation may be used as adjuvant therapy, particularly with stage 3C tumors that have attached to a nearby organ or have positive margins (tissues left behind after surgery that have cancer cells).

For people who are not fit for surgery or whose tumors are inoperable, radiation therapy and/or chemotherapy may be used to shrink and control the tumor. In cases like this, a form of radiation called stereotactic body radiotherapy (SBRT) can deliver precise beams of radiation to ensure greater tumor control.


The treatment of stage 3 colon cancer usually involves surgical removal of the affected part of the colon and chemotherapy. In some cases, radiation therapy is used.


The prognosis of stage 3 colon cancer has improved enormously in the past few decades. With improved screening methods and the introduction of newer therapies, the number of deaths (mortality rate) is now nearly half of what it was in the 1990s.

Even with improved prognosis, colorectal cancer is the fourth most common cancer in the United States, accounting for nearly 150,000 new diagnoses each year and over 50,000 deaths.

The prognosis of stage 3 colon cancer is reflected by survival rates. These are typically measured in five-year intervals and described by the percentage of people who live for at least five years following the initial diagnosis compared with people in the general population.

The survival rate is divided into three stages. The stages are based on epidemiological data collected by the National Cancer Institute and are defined as follows:

  • Localized: A tumor confined to the primary site
  • Regional: A tumor that has spread to regional lymph nodes
  • Distant: A tumor that has metastasized

By definition, stage 3 colon cancer is considered regional.

Relative 5-Year Survival Rates for Colorectal Cancer
Stage Percentage (%) of Cases Relative 5-Year Survival
Localized 37% 90.6%
Regional 36% 72.2%
Distant 22% 14.7%
Unknown 5% 39%

Survival rates are based solely on the extent of the disease. Data doesn't account for other factors that can positively or negatively influence survival times, such as age, sex, cancer type, and general health cancer.

As such, the above-listed survival rates only provide a general sense of expectations.


It's important to remember that even if colon cancer is advanced, it's still highly treatable. To better cope with the challenges of treatment and recovery, there are several things you can do:

  • Educate yourself. Knowing what to expect not only helps reduce stress but allows you to participate fully in your treatment decisions. Do not hesitate to ask questions or express fears or concerns so that you can get the clarification you need. The more that you know and understand, the better and more informed your choices will be.
  • Eat appropriately. Colon cancer and cancer treatment can affect your appetite and lead to malnutrition. Start early by working with a nutritionist to formulate a dietary strategy, including how to find nourishment if you are nauseous, have lost your appetite, or are unable to tolerate solid foods.
  • Keep active. While it is important to get plenty of rest, an appropriate amount of daily exercise can help you feel less tired and increase your ability to cope. Don't overdo it, but rather confer with your oncologist about the level and kinds of activity you can reasonably pursue, including walking, swimming, or gardening.
  • Manage stress. Rest and exercise can certainly help, but you can also engage in mind-body therapies like yoga, meditation, and progressive muscle relaxation (PMR) to better center yourself on a daily basis. If you feel severely anxious or depressed, do not hesitate to ask your healthcare provider for a referral to a psychologist or psychiatrist for help.
  • Seek support. Start by building a support network of family and friends who can help you emotionally and functionally (with transport, childcare, chores, etc.) By educating loved ones about your disease and treatment, they will be better able to understand what you need. Support groups can also be invaluable and are commonly offered by cancer treatment centers.


Stage 3 colon cancer means that a primary tumor within the colon has spread to nearby lymph nodes. Since stage 3 colon cancer is more extensive than stage 1 or 2 colon cancer, symptoms like a change in bowel habits, bleeding, or unusual tiredness from anemia tend to be more common.

The diagnosis of stage 3 colon cancer requires a biopsy, often performed during a colonoscopy. Treatment, which typically involves surgery and chemotherapy, depends on the stage (progression) and grade (severity) of the tumor, among other factors.

Even though the prognosis of stage 3 colon cancer is encouraging, with a five-year relative survival rate of 72%, being diagnosed with it can be a lot to digest. Seeking out support from others and staying active are often helpful coping strategies.

A Word From Verywell

Stage 3 colon cancer is not the same disease it was 20 years ago, and the outcomes are almost certain to improve as newer targeted therapies and immunotherapies increase survival times and the quality of life even in those with advanced metastatic disease.

Even if complete remission is not achieved, do not give up hope. Every case of colon cancer is different, with some people responding to certain therapies better than others. In addition to approved therapies, there are numerous clinical trials to explore, offering a possible bridge to future treatments.

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