When It Spreads: Breast Cancer Metastasis
"Has it spread?" Women with breast cancer wait in fear for the answer to this question when they are first diagnosed and for years afterwards. Fortunately, these days with better education and early detection techniques, most women are diagnosed before the cancer has spread.
The medical word for cancer that has spread to a distant organ is metastatis. When a breast cancer cell leaves the breast and goes to another part of the body such as the bones, lungs, liver, or central nervous system, the disease is called metastatic breast cancer. This is also known as stage IV (or stage 4) breast cancer.
Still breast cancer
After treatment, cancer can recur in one of three ways. In a local recurrence, the cancer comes back in the breast or near the scar if the woman had a mastectomy. In a regional recurrence, the cancer shows up in the lymph nodes or tissue near the breast.
With metastatic disease, the cancer has set up housekeeping in an organ far from its original home in the breast; however, it is still breast cancer. The pathologist can tell because metastasized breast cancer cells still look like breast cancer cells under the microscope, not like brain cancer or lung cancer cells. It is not uncommon for friends and family (or even the patient) to get confused and say, "Her breast cancer has spread, and now she has brain cancer." However, it is important to distinguish between brain cancer and breast cancer that has metastasized to the brain because the treatments and prognosis can be very different.
Factors affecting metastasis
Because metastasis can be a tongue twister, you may hear doctors or nurses abbreviate the term to brain mets or lung mets. In fact, because I have to stop and sound it out every time I type metastasis, I'm going to use mets too.
How likely is it that you will develop mets after your treatment? That depends on so many factors that there is no easy answer. Generally speaking, your cancer is less likely to spread if it was caught while still small, if it is estrogen-receptor positive, and slow growing. Factors that make it more likely that cancer will spread include being diagnosed before age 35, having a Her2/neu positive tumor, and having cancer in the lymph nodes. Women with inflammatory breast cancer are also likely to develop metastatic breast cancer.
Musa Meyer, an expert in metastatic breast cancer, cites the following statistics for recurrence in a paper for the California Breast Cancer Research Program. "More than half of cancers diagnosed at Stage I and II do not recur, but this of course depends upon histology of the tumor as well as the adjuvant treatments selected. A recent text on breast cancer estimates the relapse rate for patients diagnosed with Stage I breast cancer to be 20-30 percent, for Stage II 40-60 percent, and for Stage III, greater than 90 percent. About 75 percent of recurrences will occur within five years of diagnosis; however, more recent figures indicate that widespread adjuvant therapy has pushed back the time of relapse for those who do recur. With adjuvant tamoxifen, 82 percent of 60-year-old women with estrogen-receptor positive, node negative, grade 2 invasive ductal carcinoma of a centimeter or less will be disease-free at 10 years."
These numbers include local and regional recurrences, not just metastatic cancer. Note that statistics can not predict what will happen to an individual. One of my friends was told that she had a one percent chance of recurrence, but 10 years later, the breast cancer returned as a tumor near her aorta. I had a very high chance of metastasis, but 12 years later, I'm still doing fine.
Because researchers use the five-year survival rate to measure the success of treatments, many people think that if the cancer hasn't come back in five years they are cured. However, doctors at the University of Michigan label this idea a myth: "Breast cancer can recur at any time, although it is more likely to happen within the first five to 10 years: 75 percent of women who will get a recurrence see it within six years, and 25 percent recur in the 10 years after that. New hormonal therapies, including tamoxifen and aromatase inhibitors, may be delaying recurrence, so that the cancer is more likely to return after the woman stops taking those drugs."
My own oncologist says that the longest he has seen a patient go without a recurrence is 21 years.
Sometimes patients will describe themselves as "cancer free" when they finish treatment. Their doctors probably wouldn't use that term. The problem with breast cancer is that no one knows if you are cancer free. Microscopic cells could be growing undetected; they could even be dormant for a time until something triggers them back to aggressive growth. Most of the time, doctors will use the term "No evidence of disease (NED)" meaning they can not find any cancer right now. Of course, they hope the patient is indeed cancer free, but without a way to prove it, NED is a more accurate term.
Reducing the risk of recurrence
Because the factors that influence recurrence rate are so complicated, it is important for each breast cancer patient to discuss her own situation with her doctor. Many women are eligible for hormonal treatments and targeted therapies that reduce recurrence risk. Although more research is needed, it appears that diet and exercise can also play a role in decreasing recurrence. PJ Hamel has written a list of ten ways to reduce the chances of your cancer coming back. It's easy to get bogged down in worrying about cancer spreading, but it's better to let that anxiety move you to a healthier life style.
Editor's note: As of 2017, Phyllis is still doing fine.
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