What Is Metastatic Breast Cancer?
When breast cancer spreads, or metastasizes, to other parts of the body, it normally moves to one or more of the following areas:
Only rarely does it spread to the colon.
Slightly more than 12 out of every 100 women will get breast cancer in their lifetime. Of these cases, about 20 to 30 percent will become metastatic. If the cancer metastasizes, treatment becomes focused on preserving your quality of life and slowing the spread of the disease. There isn’t a cure for metastatic breast cancer.
Symptoms of Metastasis to the Colon
Symptoms associated with breast cancer that has spread to the colon include:
- changes in the stool
- abdominal swelling
- a loss of appetite
A review of cases treated at the Mayo Clinic also found that 26 percent of women who had colon metastases experienced blockage of the intestine. It’s worth noting that in the review, colon metastases is broken down to cover eight other sites, including the:
- small bowel
In other words, this percentage is covering more than just women with metastasis in the colon.
What Causes Metastasis?
Breast cancer usually starts in the cells of the lobules, which are glands that produce milk. It can also start in the ducts that carry milk to the nipple. If the cancer stays in these areas, it’s considered noninvasive.
If breast cancer cells break off the original tumor and travel via blood or the lymphatic system to another part of your body, it’s referred to as metastatic breast cancer. When breast cancer cells travel to the lungs or bones and form tumors there, these new tumors are still made of breast cancer cells. These tumors or groups of cells are considered breast cancer metastases and not lung cancer or bone cancer.
Almost all types of cancer have the potential to spread anywhere in the body. Still, most follow certain pathways to specific organs. It’s not fully understood why this happens. Information published by USC Norris Comprehensive Cancer Center says that cancers metastasize to parts of the body where the environment is similar to the organ where they originated.
Breast cancer can spread to the colon, but it’s not likely to do so. It’s even uncommon for it to spread to the digestive tract. When this does happen, cancer is more often found in the peritoneal tissue that lines the abdominal cavity, stomach, or small intestine, instead of the large intestine, which inclludes the colon.
A 26-year study of people who had breast cancer metastases, published in Clinical Breast Cancer, lists the sites breast cancer is most likely to spread to first. This study also lists the top four locations for spreading. Colon metastases are so uncommon that they don’t make the list:
- Breast cancer first spread to the bone 41.1 percent of the time.
- Breast cancer first spread to the lung 22.4 percent of the time.
- Breast cancer first spread to the liver 7.3 percent of the time.
- Breast cancer first spread to the brain 7.3 percent of the time.
When breast cancer spreads to the colon, it usually does so as invasive lobular carcinoma. This is a type of cancer that originates in the milk-producing lobes of the breast.
Diagnosing Metastasis to the Colon
If you’re experiencing any of these symptoms, especially if you’ve previously received a breast cancer diagnosis, you should speak with your doctor. Your doctor may order one or more tests to determine if cancer has spread to your colon.
When examining your colon, your doctor will look for polyps. Polyps are small growths of abnormal tissue that can form in the colon. Although most of them are harmless, polyps can become cancerous.
When you have a colonoscopy or sigmoidoscopy, your doctor will snip off any polyps that are found. These polyps will be tested for cancer. If cancer is found, this testing will show whether the cancer is breast cancer that has spread to the colon or if it’s a new cancer that originated in the colon.
A colonoscopy is a test that allows your doctor to look at the inner lining of your large intestine, which includes the rectum and colon. They use a thin, flexible tube with a tiny camera on the end called a colonoscope. This tube is inserted into your anus and up through your colon. A colonoscopy helps your doctor find:
- colon polyps
- areas that are bleeding
The camera then sends images to a video screen, which will enable your doctor to make a diagnosis. Normally, you’ll be given medication to help you sleep through the exam.
A flexible sigmoidoscopy is similar to a colonoscopy, but the tube for a sigmoidoscopy is shorter than a colonoscope and only the rectum and the lower part of the colon are examined. Medication usually isn’t needed for this examination.
Sometimes called a virtual colonoscopy, a CT colonoscopy uses sophisticated X-ray technology to take two-dimensional images of your colon. This is a painless, noninvasive procedure.
Treating Metastatic Breast Cancer
If you’re diagnosed with breast cancer that has spread to your colon, your doctor will likely order additional tests to see if the cancer has spread to other parts of your body. Once you know exactly what you’re up against, you and your doctor can discuss the best options for treatment. This may include one or more of the following therapies.
Chemotherapy drugs kill cells, especially cancer cells that are dividing and reproducing quickly. Common side effects of chemotherapy include:
- hair loss
- sores in the mouth
- an increased risk of infection
Every woman responds differently to chemotherapy. For many, the side effects of chemotherapy can be very manageable.
Most breast cancers that have spread to the colon are estrogen receptor-positive. This means that the growth of breast cancer cells is triggered at least in part by the hormone estrogen. Hormone therapy either reduces the amount of estrogen in the body or prevents estrogen from binding to the breast cancer cells and promoting their growth.
Hormone therapy is more often used to reduce further spread of the cancer cells after initial treatment with chemotherapy, surgery, or radiation. The more severe side effects that people may have with chemotherapy rarely occur with hormone therapy. The side effects of hormone therapy may include:
- hot flashes
- vaginal dryness
- mood changes
- blood clots
- bone thinning in women who haven’t reached menopause
- an increased risk of uterine cancer for women who are postmenopausal
Targeted therapy, often called molecular therapy, uses drugs that block the growth of cancer cells. Targeting the protein molecules responsible for cell growth does this. It normally has fewer side effects than chemotherapy, but the side effects may include:
- rashes and other skin problems
- high blood pressure
Some drugs used in targeted therapy can damage the heart, interfere with the body’s immune system, or cause serious damage to parts of the body.
Surgery may be performed to remove bowel obstructions or portions of the colon that are cancerous.
If you have bleeding from the bowel, it may be treated with radiation therapy. Radiation therapy uses X-rays, gamma rays, or charged particles to shrink tumors and kill cancer cells. Side effects may include:
- skin changes at the site of the radiation
- increased urination
What Is the Outlook for People with Metastatic Breast Cancer?
Although cancer that has metastasized can’t be cured, advancements in medicine are helping people with metastatic breast cancer lead longer lives. These advances are also improving the quality of life for people living with the disease.
According to the American Cancer Society, people with metastatic breast cancer have a 22 percent chance of living at least five years after their diagnosis. It’s important to remember that this is a general figure and doesn’t account for your individual circumstances. Your doctor can provide you with the most accurate outlook based on your individual diagnosis, medical history, and treatment plan.