Metastases to Rectum

When cancer spreads to the rectum from another part of the body, or when rectal cancer spreads to distant organs, it creates unique challenges that require specialized care and treatment approaches.

Table of contents

• What Are Metastases to the Rectum
• Types of Metastatic Rectal Disease
• Common Sites Where Rectal Cancer Spreads
• When Metastasis Occurs in Rectal Cancer
• Symptoms of Metastatic Rectal Disease
• How Metastases Are Diagnosed
• Treatment Options
• Coping with Metastatic Rectal Disease

What Are Metastases to the Rectum

Metastases to the rectum can occur in two distinct ways. The first involves cancer that starts in the rectum itself and then spreads to other parts of the body. This is called metastatic rectal cancer, also known as stage 4 or advanced rectal cancer^[3]. The second, much rarer situation involves cancer that begins somewhere else in the body and spreads to the rectum. These are called secondary metastatic lesions to the rectum^[2].

The rectum is the last several inches of the large intestine, extending from the end of the colon to the anus^[6]. When cancer cells develop the ability to break away from their original location and travel through the bloodstream or lymphatic system to distant sites in the body, this process is called metastasis^[5].

Secondary metastatic lesions to the colon and rectum are rare. However, doctors are becoming more aware of them during follow-up investigations of patients with other primary cancers. The incidence of these metastases appears to be increasing as physicians become more vigilant in looking for them^[2].

Types of Metastatic Rectal Disease

Understanding the difference between primary metastatic rectal cancer and secondary metastases is important. If cancer starts in the rectum and spreads to the liver or lungs, it is still considered rectal cancer, not liver or lung cancer. The cancer cells retain the characteristics of rectal cancer cells even when they are found in other organs^[11].

When rectal cancer has spread to a limited number of sites in the body—typically five or fewer tumors—doctors may use the term oligometastatic disease. This specific situation may offer different treatment possibilities compared to cancer that has spread more widely^[11].

Common Sites Where Rectal Cancer Spreads

When rectal cancer spreads beyond the rectum, it most commonly travels to specific organs and body areas. The liver is the most frequent destination, followed by the lungs. Other common sites include the lining of the abdominal cavity (called the peritoneum) and lymph nodes^[3][11].

Up to half of all people diagnosed with colon or rectal cancer will eventually develop cancer in other parts of the body^[3]. When both rectal cancer and liver metastases are present at the same time, this creates particularly complex treatment decisions. About 20 to 25 percent of patients present with liver metastases at the time of their initial rectal cancer diagnosis^[8].

When Metastasis Occurs in Rectal Cancer

Research has revealed surprising findings about when rectal and colon cancers begin to spread. Contrary to what many doctors previously believed, metastasis may occur very early in the disease process—potentially years before the original cancer is diagnosed through screening tests^[5].

Studies examining the genetic makeup of both primary rectal tumors and their metastases found that in about 80 percent of patients, the cancer cells that formed distant tumors broke away from the original tumor very early in its development. The genetic mutations that gave these cells the ability to spread were already present throughout different regions of the primary tumor^[5].

This finding suggests that a single cell, or a small group of genetically similar cells, breaks off from the original tumor early and establishes metastases elsewhere in the body. This has important implications for understanding why some patients develop metastatic disease despite treatment of their primary tumor^[5].

Symptoms of Metastatic Rectal Disease

Metastatic rectal cancer may not always cause symptoms, even when it has spread to other organs^[3]. When symptoms do occur, they can be similar to those of rectal cancer that hasn’t spread, or they may reflect the involvement of other organs.

General symptoms may include:

• Changes in bowel habits, such as increased diarrhea, constipation, or changes in the shape of stools
• Rectal bleeding or blood in the stool
• A feeling that the bowel doesn’t empty completely
• Ongoing discomfort in the belly area, including cramps, gas, bloating, or pain
• Feeling full soon after eating
• Unexplained weight loss
• Tiredness and weakness
• Iron deficiency anemia
• A lump in the belly button area

These symptoms are drawn from information about stage 4 colon cancer, which behaves similarly to metastatic rectal cancer^[3][6].

When rectal cancer spreads to the liver, specific symptoms may develop, including pain in the upper right part of the abdomen, yellow skin and eyes (a condition called jaundice), and unusual tiredness^[11]. If cancer spreads to the lungs, patients may experience shortness of breath, frequent respiratory infections, coughing, or chest pain^[11].

How Metastases Are Diagnosed

Diagnosing metastatic rectal disease involves a combination of different tests. Doctors use imaging tests, laboratory tests, genetic testing, and tissue samples to understand the extent and characteristics of the cancer^[9].

Imaging tests create pictures of the inside of the body to look for areas of cancer. CT scans and MRI scans are the main imaging tests used to detect rectal cancer and assess how far it has spread. A PET scan may also be helpful in deciding if surgery is an option for cancer that has spread outside the rectum^[9].

A biopsy involves removing a sample of tissue for testing in a laboratory. For rectal cancer, this sample is often collected during a colonoscopy, though sometimes surgery is needed to obtain the tissue. Laboratory tests can determine whether the cells are cancerous, what type of cancer it is, and identify genetic changes in the cancer cells that might guide treatment decisions^[9].

Molecular and genetic testing examines the cancer cells for specific gene changes that affect how the cancer grows and responds to treatment. Some medicines only work for cancers with certain genetic features, so these tests help doctors choose the most effective treatment^[9].

A blood test called carcinoembryonic antigen (CEA) testing measures a protein made by some colorectal cancer cells. High levels of CEA can indicate the presence or progression of cancer, especially in advanced disease^[9].

Treatment Options

Treatment for metastatic rectal cancer aims to keep the disease under control, relieve symptoms, and maintain quality of life. In some cases, treatment can control the cancer for a long time. For a small number of people whose cancer has spread to just one other body part that can be completely removed surgically along with the rectal cancer, a cure might even be possible^[12].

Stage 4 rectal cancer typically requires complex treatment strategies. Available treatments may include chemotherapy, surgery, targeted therapy, immunotherapy, or radiation^[3]. The specific combination depends on where the cancer has spread, the patient’s overall health, and the genetic characteristics of the cancer.

For patients with both rectal cancer and liver metastases, treatment decisions become particularly complex. Doctors must decide the order of treatments—whether to address the rectal cancer first, the liver metastases first, or both simultaneously^[8].

When metastatic rectal cancer causes specific symptoms like bowel obstruction or bleeding, additional procedures may help. These can include placement of stents (tubes that keep the bowel open), laser ablation (using heat to destroy tissue), or surgical procedures to remove or bypass the blockage^[18].

Some specialized centers offer advanced treatments not available everywhere. These may include hepatic artery infusion, which delivers chemotherapy directly to liver tumors, or procedures like ablation to destroy tumors using heat or cold^[11].

Coping with Metastatic Rectal Disease

Learning that cancer has spread or cannot be cured is distressing and often comes as a shock. It’s normal to feel uncertain, anxious, and unable to think about anything else. Many people find it difficult to process this news initially^[12].

Understanding your diagnosis and what to expect can make it easier to cope. Important topics to discuss with your doctor or specialist nurse include what your diagnosis means, what is likely to happen, what treatments are available, how treatment can help, and what side effects might occur^[12][13].

Having a good relationship with your healthcare team is important, especially since you’ll be seeing them frequently if treatment is involved. Make sure you feel comfortable with your care providers and that they understand your concerns and preferences^[13].

Talking about your situation with family and friends can provide support, though this can be challenging. Some people find it helpful to speak with someone outside their immediate circle, such as a counselor. Support groups connecting you with others facing similar challenges can also be valuable^[12][13].

Planning what you want to do and thinking about your priorities can help you feel more in control. While some future plans may no longer be realistic, you might accomplish things you always wanted to do but hadn’t made time for. Your specialist nurse can help you arrange treatment around your plans when possible^[12].

Remember that your cancer diagnosis isn’t the end—it’s the beginning of a fight. Even with a serious diagnosis, there’s still life between treatments. Making time for activities you love and connecting with family members remains important^[13].

Physical changes may occur as a result of the cancer or its treatment. Community cancer nurses or symptom control nurses can provide support at home. If you’ve had surgery resulting in an ostomy (an opening from the bowel to the outside of the body), you’ll receive support to learn how to manage it^[12].

Ultimately, treatment decisions are yours to make. Spend time thinking about how you want to live with cancer. Fighting as hard as possible isn’t for everyone, and that’s acceptable. Don’t let others pressure you into treatments you don’t want^[13].