As cancer rates rise among young people, experts around the world are launching major research in an attempt to discover what is behind the increase.
But there’s another question about cancer that’s equally puzzling: Why do some cancers keep coming back?
If five years have passed and there are no signs of cancer, patients are generally considered cured, as few see their disease return.
But with some types of breast cancer, up to a quarter of women will be diagnosed with the disease again, sometimes decades later.
Now, medical experts around the world are looking for the reasons.
Dr Francisco Contreras, director and president of Oasis of Hope Hospital in Mexico, told DailyMail.com: ‘The thorn in the side of oncology is the recurrence of cancer after successful treatment.
“This problem varies widely depending on the types of cancer and their stage, the aggressiveness of the disease and the type of therapy administered.”
On average, breast cancer comes back between three and 25 percent of the time. Experts believe that young and obese women are most at risk, as well as those with more aggressive types.
U.S. data suggests that deaths from breast cancer, the most common form of the disease in women, have steadily declined over time thanks to a host of new treatments such as hormone therapies and drugs that help the immune system. to destroy cancer cells..
However, the Breast Cancer Research Foundation estimates that diagnoses in women under 50 have increased two percent annually over the past five years.
Although these advances have proven to be very effective in destroying the disease, they have not prevented it from reappearing many years later.
Dr. Contreras noted that he recently saw a patient whose breast cancer returned 25 years after she was declared cancer-free.
One possible reason, she suggests, for a small number of women, could be the recent move to minimally invasive techniques to treat the disease, such as surgically removing a lump, rather than the entire breast.
While this may improve quality of life, the disease may recur in remaining tissues.
Another reason could have to do with hormones, specifically the female sex hormone estrogen. About 80 percent of breast cancers are ER positive, meaning the cancer cells have receptors that allow estrogen to grow.
It is estimated that in about a quarter of patients with this condition, cancer cells remain and then awaken years, even decades, later.
Additionally, one in five breast cancers is genetically programmed to create higher levels of the HER2 protein, which has been shown to help breast cancer cells grow faster. These breast cancers are known as HER2 positive.
In ER-positive breast cancer, estrogen stimulates the division of breast cells, increasing the risk of cancerous mutations in the tissue’s DNA.
While most patients with this type of disease take hormone-suppressing medications after cancer treatment to offset this risk, some patients stop taking them too soon and they are not always effective.
Most patients with HER2-positive breast cancer do not experience recurrence; The HER2 gene is known to mutate and cause the cancer to come back and spread further.
There are also other types of breast cancer that have long been known to be particularly aggressive.
Triple negative breast cancer (TNBC), for example, is known to grow rapidly; Some research suggests that up to 50 percent of patients experience a recurrence and 37 percent die within five years of surgery.
TNBCs, which account for 10 to 15 percent of all breast cancers, also do not have estrogen or progesterone receptors or higher levels of HER2, meaning there are fewer targeted treatment options.
Meanwhile, inflammatory breast cancer only accounts for one to five percent of breast cancers. Unlike most forms of the disease, it does not cause a lump and tends to occur in women under 40 years of age.
Shannen Doherty (left) was first diagnosed with breast cancer in 2015 and went into remission in 2017. However, her cancer recurred in 2020 and is now in stage four. Olivia Newton-John (right) was first diagnosed with breast cancer in 1992. She died from the disease nearly three decades later, in 2021.
Dr. Anne Peled, a breast cancer surgeon and co-director of Sutter Health Pacific Medical Center in San Francisco, told DailyMail.com: “Certain types of breast cancer, such as HER2-positive and triple-negative breast cancers, have more likely to reappear and are also more likely to reappear.” reappear in the first years after diagnosis.
“While this makes going through the first few years after treatment much more stressful for our patients with these types of breast cancer, we love to celebrate with them once they have passed these cancer-free years, as their risk of returning to get cancer after that. It’s very low.’
However, he noted that while ER-positive and HER2-negative breast cancers are generally less likely to occur, the disease is more likely to return decades later.
Women diagnosed with breast cancer before age 35 are also thought to be at higher risk of recurrence, as they are more likely to have aggressive forms of the disease and be diagnosed at later stages.
Dr Jennifer Son, a breast surgeon at MedStar Georgetown University Hospital in Washington, DC, told DailyMail.com: “The younger a patient is, the greater the risk of recurrence because they have many more years to live.”
It also noted that, on average, obese women are about 18 percent more likely to experience a breast cancer recurrence. This is because fat cells produce estrogen, which helps HER2-positive tumors grow.
It is also thought that in some cases, the treatment shrinks tumors so small that they cannot be detected on follow-up scans, so they may grow back.
Breast cancer recurrence can present unique challenges, experts also warned.
For example, Dr. Son noted that “if patients have a recurrence and have already had a lumpectomy and radiation, they typically cannot have radiation to the same breast again.”
And secondary tumors can recur and be more aggressive, Dr. Contreras said, because they can become resistant to previously used treatments, such as chemotherapy and radiation.
Secondary tumors can also spread to other areas such as lymph nodes, requiring more aggressive protocols.
However, thanks to targeted therapies, many women live for several years, or even decades, with advanced-stage breast cancer.
Recent data from the Fred Hutch Cancer Center shows that 17 percent of women with breast cancer that has spread to other organs have been living with the disease for more than 10 years.