Stage 3 colon cancer is when the cancer cells reach the lymph nodes near the tumor. While doctors consider stage 3 a more advanced form of cancer, it can be curable depending on certain factors. Treatment may remove all the cancer cells and put the disease into remission.

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Colon cancer diagnoses fall within stages 0 to 4.

This article explores the symptoms, diagnosis, treatment, and outlook for people with stage 3 colon cancer.

The symptoms of colon cancer could begin at any stage, depending on the size, location, and number of tumors.

During earlier stages, people may experience mild or no symptoms. Routine screening increases the chances of catching colon cancer at an earlier stage.

The symptoms of colon cancer develop as a tumor within the colon narrows the passageway of the intestine. This affects the movement of digested food, waste, fluids, and gas through the colon.

General symptoms of advanced cancer can include:

  • fatigue
  • low energy levels
  • having less appetite

Colon cancer may increase the likelihood of experiencing other symptoms, such as:

  • bowel obstructions
  • constipation
  • diarrhea
  • changes to usual bowel patterns
  • abdominal pain and cramping
  • bright red blood in the stool or dark brownish-black stool
  • rectal bleeding
  • nausea and vomiting
  • bloating or distention
  • unintentional weight loss
  • anemia

People may experience any of the symptoms of colon cancer at any stage. It often depends on the size, location, and number of tumors and how cancer affects the individual.

When doctors suspect colon cancer, they recommend multiple tests and exams. These tests start with a medical history to review any observable signs and symptoms and an assessment of a family history of cancer.

A healthcare professional will then complete a physical exam to assess for tenderness, swelling, typical bowel sounds, and lumps.

Depending on these exams, a doctor may order further testing. Common tests to diagnose colon cancer include:

  • Blood tests: These include complete blood count, liver function tests, and tumor marker blood tests.
  • Stool tests: These include fecal occult blood tests or fecal immunochemical testing to test for blood in the stool.
  • CT scan: This imaging test creates a 3D image of the colon and shows the size of the tumor. It may show abnormalities in the colon, such as a mass or thickening of the colon wall, which could indicate colon cancer.
  • Colonoscopy: This is a camera on the end of a flexible tube that doctors insert into the anus. Doctors will move it up to the colon to view any tumors that are then visible using the device.
  • Biopsy: Doctors will remove a tumor sample to aid in a definitive diagnosis and classify the tumor to determine the best treatment options.

The diagnostic process for the stage of cancer

A pathologist will confirm the diagnosis of colon cancer when they take a biopsy during a colonoscopy. This will show any colon cancer cells under a microscope.

After the diagnosis, a person may undergo surgery to remove their colon and lymph nodes. If the lymph nodes contain colon cancer cells, which a biopsy will determine, they will diagnose a person with stage 3 colon cancer.

If there are no cancer cells in the lymph nodes, doctors will diagnose a person with stage 2 or 1 colon cancer, depending on how deep the colon tumor penetrates the colon wall.

The pathologist will then determine the subcategory of stage 3 colon cancer using the National Cancer Institute’s staging system. The substages of stage 3 depend on the depth of invasion and the number of lymph nodes involved.

Treatment of stage 3 colon cancer largely depends on the size, location, and amount of lymph node involvement.

A team of medical specialists will determine the best treatment options for the individual’s needs, including:

  • oncologists
  • surgical oncologists
  • gastroenterologists
  • a general doctor

According to a 2022 article, the main treatment for stage 3 colon cancer involves surgical resection. This surgery may remove part or all of the colon depending on the tumor size, number, and location. The surgeon removes any adjacent tissue and lymph nodes that may contain cancer cells during surgery.

Researchers recommend that almost all people with stage 3 colon cancer receive chemotherapy treatment after surgery to lower the risk of recurrence or in combination with surgery.

The medical professionals will determine the length of treatment while considering the possible risks of neurotoxicity from chemotherapy. Treatment duration is typically 3–6 months, depending on the method.

According to a 2020 study, some people may benefit from lowering the treatment time to 3 months if they have a high risk for possible toxicities.

The outlook for people with stage 3 colon cancer continues to improve with medical advancements. The number of new cases and mortality continues to decline, likely relating to improved screening and early diagnosis.

However, even with scientific improvements, colon cancer has the second-highest mortality rate of all cancers.

For people with colon cancer, following up with a doctor consistently and completing recommended treatments improves their chances of positive outcomes. Delaying treatment may increase the risks of the disease progressing to a more severe stage.

Below are frequently asked questions regarding stage 3 cancer.

Is stage 3 cancer curable?

Stage 3 cancer can be curable, but it largely depends on the size, location, and number of tumors.

What is the success rate of treatment for stage 3 cancer?

Surgical resection may cure about 50% of people with stage 3 colon cancer, while another 30% benefit from adjuvant treatment, such as chemotherapy. However, 20% still experience disease recurrence despite the adjuvant treatment.

Can stage 3 cancer move to stage 4?

Stage 3 cancer can progress to stage 4 by spreading to other body parts. How quickly the disease progresses depends on the type of cancer, genetics, and other factors.

Stage 3 colon cancer occurs when a primary tumor develops in the colon and impacts nearby lymph tissue. It may cause symptoms such as abdominal pain, blood in stool, changes in bowel habits, fatigue, and weight loss.

The diagnosis requires multiple tests, including CT scans, colonoscopy, and a biopsy.

Treatment usually includes surgery and chemotherapy.

The prognosis for people with stage 3 colon cancer continues to improve with continued advancements in medical treatments.