There's always a possibility that the cancer will return. Doctors call this a recurrence. It can happen months, years, or even decades after the first cancer. It may be in the same breast as before or in a different part of the body, such as the lungs or bones.
Whether your cancer comes back depends on many factors, including the type of breast cancer you have, its stage, and how you respond to treatment.
The idea that your cancer might return can be scary. But your oncologist will follow you closely to ensure you start treatment quickly if it does come back. Also, know that you are not powerless.
"There's so much that patients can do, from lifestyle interventions to looking at exposures around them and making small changes as they're able to," says Alissa Huston, MD, professor of medicine, breast medical oncologist, and co-medical director of the Pluta Integrative Oncology and Wellness Center at the University of Rochester Wilmot Cancer Institute in Rochester, NY.
Here's a closer look at what determines your risk for breast cancer recurrence.
Tumor Characteristics
Everyone's cancer behaves in different ways.
"Breast cancer isn't one disease," says Daniel Hayes, MD, the Stuart B. Padnos Professor of Breast Cancer Research at the University of Michigan Rogel Cancer Center in Ann Arbor, Michigan. Some cancers respond to the hormones estrogen and progesterone. Others make too much of the human epidermal growth factor receptor 2 (HER2) protein. The size, stage, and hormone receptor status of the cancer all affect the likelihood of a recurrence.
Hormone Receptor Status
Certain hormones and proteins help breast cancer cells grow.
Estrogen receptor (ER)-positive and progesterone receptor (PR)-positive breast cancers have proteins called receptors on the surface of their cancer cells. When estrogen or progesterone attaches to these receptors, it helps the cancer cells grow. HER2-positive breast cancers make too much of the human epidermal growth factor receptor 2 protein. They grow faster than other breast cancer types.
Triple-negative breast cancers don't have estrogen or progesterone receptors, and they don't make too much HER2 protein. The risk of recurrence for triple-negative breast cancer is highest because it's a very aggressive and hard-to-treat type. The risk is lowest for cancers that are triple-positive: ER-positive, PR-positive, and HER2-positive.
HER2-positive breast cancer has been a "moving target," Hayes says. It used to recur in up to half of people within 10 years, but that's not the case anymore.
"Because of the [targeted] therapies that have been developed since the 1990s, starting with Herceptin…HER2-positive disease is almost the best kind of breast cancer you can have now."
People with early stage ER-positive or PR-positive breast cancer have a low chance of recurrence in the first five years after treatment. But their risk for a distant (in another part of your body) recurrence lasts for decades. Up to 23% will have a recurrence within five years after their diagnosis, and 38% will have a recurrence within 25 years after their diagnosis.
Cancer Type
Doctors also divide breast cancers into types. Invasive ductal carcinoma is the most common type. Inflammatory breast cancer only makes up 1%-3% of all breast cancers. But it has the highest recurrence rate in the first five years after treatment because it's aggressive and hard to treat. Up to half of inflammatory breast cancers come back.
Stage
In general, the higher the stage of cancer, the more likely it is to return. The risk of stage I breast cancer coming back within 10 years is less than 10%. For stage II, the risk is 10%-20%. And by stage III, recurrence rates are 30%-50%.
But having a later stage cancer doesn't mean your cancer will definitely return. Sometimes, stage I breast cancer comes back and stage III cancer doesn't.
Also important is the TNM stage, which includes other details about the cancer. "The size of the tumor, whether or not you have lymph node involvement, and how many lymph nodes you have," Hayes says.
Bigger cancers and ones with more positive lymph nodes are more likely to return. There's a 6% chance of recurrence within five years if the surgeon doesn't find cancer in your underarm lymph nodes. The risk rises to 25% if cancer is in those lymph nodes.
Age at Diagnosis
Being diagnosed before age 35 increases the risk of a recurrence. In one study, people aged 21-35 with early-stage breast cancer were almost four times as likely to have a distant recurrence 5-10 years after surgery than people aged 41-45. This may have more to do with the tumor than with age. Younger people tend to have more aggressive, fast-growing cancers than older people.
Treatment Response
How you treat breast cancer — and how well your cancer responds to that treatment — can affect your risk for recurrence. Your doctor will check how well the cancer responded by looking at tissue removed during surgery under a microscope. A complete pathologic response means you have no sign of cancer in the removed tissue.
Even with an aggressive type like triple-negative breast cancer, people who have a complete pathologic response after treatments such as surgery, chemotherapy, and immunotherapy are at lower risk for recurrence than those whose cancer doesn't respond as well to treatment.
Hormone Exposure
Could taking hormone replacement therapy (HRT) during menopause lead to a recurrence of hormone-driven breast cancers? Researchers have investigated this, but they found mixed results. Some studies showed an increase in recurrence rates among breast cancer survivors who took HRT. Others didn't find any increase.
The general recommendation is to not prescribe body-wide hormones for people with estrogen- or progesterone-fueled breast cancer.
"Your goal is to reduce and block those hormones, not provide those hormones," Huston says.
But because everyone is different, treatment needs to be personalized based on your breast cancer risks and menopause symptoms.
Lifestyle
Researchers have studied whether lifestyle factors such as diet and exercise lower the chance of the cancer returning. It's been hard to draw conclusions because most studies have been observational. Researchers didn't put participants on a specific diet or exercise plan. They just asked about these lifestyle habits.
There is some evidence that following lifestyle recommendations might be helpful. In one study, people with HR-positive breast cancer who followed recommendations about diet, exercise, and smoking were 37% less likely to have a recurrence than those who didn't. There are other reasons to follow a healthy lifestyle.
"What I've told my own patients is, you should live a healthy lifestyle, not necessarily for breast cancer, but so you don't have a heart attack after you've survived breast cancer," Hayes says.
Diet
What you eat could make a difference in your outlook. In another study, people with high-risk breast cancer who most closely followed dietary recommendations were 41% less likely to have their breast cancer come back than those who made the least improvements to their diet. A low-fat diet high in fruits, vegetables, and whole grains may lower your risk of death after breast cancer.
Exercise
Regular exercise is also important for staying healthy during breast cancer treatment. Research found that people at high risk for recurrence who do 2.5 hours of moderate intensity exercise per week before and after their diagnosis have a 50% lower risk of recurrence. In premenopausal people with hormone receptor-negative breast cancer, physical activity increases the length of time before the cancer comes back or spreads.
Weight
Having a high body mass index (BMI) increases the risk of not only getting breast cancer but also its recurrence. One possible reason is that people with obesity tend to have bigger tumors and more lymph nodes with cancer. Fat tissue also increases the production of estrogen, which helps some breast cancers grow.
Smoking
There are many reasons to quit smoking during cancer treatment. For one thing, it may improve your odds of surviving. Studies are mixed on whether smoking increases the risk of recurrence. But quitting, especially if you're a heavy smoker, benefits your health in general.
How Risks Change Future Care
Finishing your treatment can come as a relief. But knowing that it might return may cause a lot of anxiety. Your treatment team is there to guide you through the next steps, and they'll carefully monitor you for a recurrence.
"It's important for patients to come in for their visits and see their oncologist or their oncology care team, so that the team has a sense of whether there are any new symptoms or anything new going on that needs to be investigated further," Huston says.
You are an essential part of the treatment team. Follow your oncologist's recommendations. Take an aromatase inhibitor, if prescribed, to lower your risk for recurrence. See where you can make healthy changes to your diet or add more exercise to your day.
Let your doctor know if you notice any changes in your breast health.
"If you have a new symptom that for you is unexplained, lasts longer than it should, or just won't go away, go see your doctor," Hayes says.
Finally, know that a recurrence is not destined to happen.
"Just because someone's at higher risk, it doesn't necessarily mean that they will experience a recurrence," Huston says. "Even if cancer does recur, we have so many treatments to help."
