Colorectal Cancer Stages and Treatment Effectiveness
Medically reviewed by Jay N. Yepuri, MDMedically reviewed by Jay N. Yepuri, MDColorectal cancer (CRC) is a term for cancers that begin in the colon or rectum. Determining the stage of colorectal cancer is important because it helps determine treatment options and, ultimately, the prognosis of the disease.This article will review the stages of colorectal cancer, how each stage is determined, and how this information can relate to survival outcomes.
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Colorectal Cancer (of Large Intestine) StagesColorectal cancer is classified into five stages, from stage 0 to stage 4. Stages are determined based on how far the cancer has spread from its original location. Factors that determine the stage include the size of the tumor, whether it has spread into any lymph nodes, and metastases (growth in distant areas).These stages help oncologists (cancer specialists) determine the prognosis and best treatment options, which can include a combination of surgery, chemotherapy, targeted therapy, or radiation. Cancers discovered at an earlier stage have a better survival rate.Stage 0 (Carcinoma in situ)Stage 0 is the earliest stage of CRC, in which abnormal cancer cells are limited to only the inner lining of the colon or rectum. These cells haven’t grown into deeper layers or spread beyond the colon or rectum.Stage 1In stage 1 CRC, cancer has grown into the deeper layers of the colon or rectum wall but hasn’t grown beyond it. Cancer has not reached the lymph nodes or distant organs.Stage 2Stage 2 CRC is divided into three substages, 2A, 2B, and 2C:In stage 2A, the cancer has spread to the wall of the colon or rectum but hasn’t gotten to nearby organs or lymph nodes.Stage 2B is more advanced, in which the tumor has grown through the wall to the outer layers or tissues nearby but has not spread to the lymph nodes or other organs.Stage 2C, the most advanced within stage 2, indicates that the cancer has spread to a nearby organ or structure but has not gotten into the lymph nodes.Stage 3Stage 3 colorectal cancer is more advanced than stage 2. It also has three substages: 3A, 3B, and 3C. In this stage, cancer has spread past the inner layers of the colon or rectum and into nearby lymph nodes. The size of the tumor can vary, but it is typically a larger tumor and it has grown deeper into lymph nodes and nearby tissue, such as fat.Stage 4Stage 4 is the most advanced stage of CRC and also has three subgroups:In stage 4A, the cancer has spread beyond the colon or rectum to a distant organ or distant lymph nodes but not into the lining of the abdomen, which is called the peritoneum.Stage 4B means that the cancer has grown even further and has spread to more than one distant organ or set of lymph nodes.Stage 4C is the most advanced stage and means that cancer has spread to multiple distant sites and the peritoneum.Colorectal Cancer Staging and Prognosis After the stage of colorectal cancer has been determined, decisions about treatment options can be made, and with that, an opinion on prognosis. However, getting to that point takes multiple steps, from diagnosis to staging. In addition to the stage, the exact type of cancer cells present is also a factor in treatment and prognosis. DiagnosisDiagnosing colorectal cancer begins with a healthcare provider's physical examination and review of medical and family history to assess for any concerning signs or symptoms.Even if any signs or symptoms aren’t present, screening for CRC is recommended for people aged 45 and older. Screening tests can include:Fecal immunochemical test (FIT)Guaiac-based fecal occult blood test (gFOBT)Stool DNA testColonoscopyComputed tomography (CT) virtual colonoscopySigmoidoscopyThe appropriate screening test can be determined in conversation with your healthcare team. However, if any of the screening tests indicate the possibility of cancer cells, you will need a colonoscopy.During a colonoscopy, a colonoscope (a long, flexible tube with a camera) examines the inside of the colon and rectum. If any concerning areas are seen, a biopsy of these cells can be collected and tested for the presence of cancer.Biopsy and PathologyAfter a biopsy is taken, it is evaluated in a lab for the presence of cancer cells and to determine their type and other characteristics. The most common type of CRC is adenocarcinoma, which is found in over 90% of CRC. Other types of CRC include:Signet ring cell adenocarcinomaMedullary carcinomaAdenosquamous carcinomaPathology testing includes molecular testing. Evaluating the presence or absence of certain molecular subtypes can help the oncology team make treatment decisions. Molecular mutations they may look for can include:Microsatellite instabilityKRASNRASBRAFMLH1P53In addition to testing the cancer cells, blood work will likely be done to evaluate liver and kidney function, blood cell counts, and a carcinoembryonic antigen (CEA) test. A CEA can serve as a tumor marker. In many cases of CRC, the CEA is elevated at diagnosis and should decrease with treatment.StagingThe staging process takes place after the diagnosis of CRC. During this process, further imaging studies may determine the extent to which the cancer has or hasn’t spread in the body. Imaging studies that may be ordered can include:CT scanMagnetic resonance imaging (MRI)Positron emission tomography (PET) scanThe specifics of each stage of CRC are reviewed above. Does Treatment Cure Colorectal Cancer?Stage 1 colorectal cancer is considered to be curable because the cancer is located in the walls of the colon or rectum but hasn’t spread anywhere else. Treatment for stage 1 CRC usually involves surgery to remove the tumor as well as some of the healthy tissue around it. Often, no additional treatment is required.About one-third of newly diagnosed CRC cases are found in the early stage. The five-year relative survival rate for stage 1 CRC is 91.1%. This means that 91.1% of people with stage 1 CRC will survive their cancer for at least five years.Stage 2 CRC can be cured as well. The main treatment for Stage 2 CRC is surgery to remove the tumor. In some cases, especially those that are high-risk, chemotherapy might be recommended. The majority of people with stage 2 CRC will survive their cancer as well.Stage 3 CRC, though more advanced than earlier stages, is curable. Treatment is usually surgical removal of the tumor and lymph nodes followed by a few months of chemotherapy. Radiation may also help. About 36% of new CRC cases are found in this stage, and the five-year relative survival rate is 73.7%.Stage 4 colorectal cancer, in which the cancer has spread to distant organs such as the liver or lungs, is usually not considered curable. Treatment is focused on shrinking what cancer is present and trying to keep it from growing as long as possible. Treatment for stage 4 CRC can include:SurgeryRadiationChemotherapyTargeted medicationsImmunotherapyAbout a quarter of those newly diagnosed with CRC are diagnosed with stage 4 disease. The five-year relative survival rate for stage 4 CRC is 15.7%. Survival Rate Is Not Your PrognosisYour healthcare team can explain your individual prognosis, which is based on many factors unique to you. Overall survival rates do not apply to individuals. They also do not take into account newer treatments developed within the past five years.
Stage of Recurrent Colorectal Cancer When treatment for CRC is complete, a surveillance plan will be determined. During surveillance, regular follow-ups, blood tests, and imaging studies will evaluate for the recurrence of CRC. The schedule of such tests will be determined by the type of CRC and its stage.Recurrence of CRC may not exhibit any symptoms, though some may be present. Symptoms may include:Abdominal painChanges in bowel movementsUnintentional weight lossFatigueBack painShortness of breathIf CRC has been found again, additional testing will likely be done to determine the extent of the disease. A new biopsy may need to be taken as well. The original stage that was diagnosed won’t change, but the recurrent cancer will be restaged and designated with an “r” for recurrence.Summary Colorectal cancer grows in the colon or rectum and is assigned in five stages, from stage 0 to stage 4. Staging helps determine the treatment needed as well as the prognosis. When CRC is detected at its earliest stages, it has a 91.1% five-year relative survival rate, which decreases to 15.7% when diagnosed at stage 4. Following treatment, surveillance strategies look for recurrent disease, which can be asymptomatic or present with symptoms like abdominal pain and weight loss. If recurrent CRC is found, it is restaged to help determine treatment plans. Read the original article on Verywell Health.
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