By Emily Joshu, health reporter for Dailymail.Com
10:33 p.m. June 18, 2024, updated 10:35 p.m. June 18, 2024
As cancer rates soar among young people, experts around the world are launching major investigations to try to discover what is behind the increase.
But there’s another equally puzzling question about cancer: why do certain types of cancer 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 certain types of breast cancer, up to a quarter of women will be diagnosed with the disease again, sometimes decades later. Today, medical experts around the world are looking for the reasons for this phenomenon.
Dr. Francisco Contreras, director and president of Oasis of Hope Hospital in Mexico, told DailyMail.com: “The thorn in the side of oncology is cancer recurrence after successful treatment. »
“This problem varies greatly depending on the types of cancer and their stage, the aggressiveness of the malignancy, and the type of treatment given.”
Breast cancer, the most common form of the disease among women, affects more than 300,000 Americans each year and kills more than 42,000.
Mortality rates have steadily declined over time, from about 48 deaths per 100,000 women to 27 per 100,000 over the past 40 years, thanks to a host of new treatments like hormone therapies and medications that help the immune system to kill cancer cells.
However, the Breast Cancer Research Foundation estimates that diagnoses in women under 50 have increased by 2% per year over the past five years.
Although these advances proved very effective in destroying the disease, they did not prevent its reappearance several years later.
Dr. Contreras said he recently saw a patient whose breast cancer had returned 25 years after she had been declared cancer-free.
One possible reason, he suggests, for a small number of women, could be the recent move toward less invasive techniques for treating the condition, such as surgically removing a lump rather than the entire breast.
Although this can improve quality of life, the disease can return in the remaining tissues.
Another reason could be related to hormones, namely 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 disease, cancer cells persist and then reappear years or even decades later.
Additionally, one in five breast cancers are genetically programmed to create higher levels of the HER2 protein, which helps breast cancer cells grow faster. These breast cancers are called HER2 positive.
In ER-positive breast cancer, estrogen stimulates breast cell division, which increases the risk of cancerous mutations in the tissue’s DNA.
While most patients with this type of disease take hormone suppressing drugs after cancer treatment to account for 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 a recurrence, the HER2 gene is known to mutate and cause the cancer to come back and spread.
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 be growing rapidly, with some research suggesting 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 treatment options. targeted treatment.
Inflammatory breast cancer, on the other hand, represents only one to five percent of breast cancers. Unlike most forms of the disease, it does not cause a lump and usually occurs in women under the age of 40.
Dr Anne Peled, a breast cancer surgeon and co-director of Sutter Health Pacific Medical Center in San Francisco, told DailyMail.com: “Some types of breast cancer like HER2 positive and triple negative breast cancers are more likely to relapse and are also more likely to recur. recur in the first years following diagnosis.
“While this makes 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 get through these cancer-free years because their risk of getting it again cancer later. is very weak.
However, she noted that while ER-positive and HER2-negative breast cancers are less likely to occur overall, the disease is more likely to return decades later.
Women diagnosed with breast cancer before the age of 35 are also thought to be at increased risk of recurrence, as they are more likely to have aggressive forms of the disease and be diagnosed at later stages.
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Dr Jennifer Son, a breast surgeon at MedStar Georgetown University Hospital in Washington DC, told DailyMail.com: “The younger a patient is, the higher the risk of recurrence, as she still has many years to live. »
She also noted that on average, obese women have about 18 percent greater risk of breast cancer recurrence. Indeed, fat cells produce estrogen, which promotes the growth of HER2-positive tumors.
It is also thought that in some cases the treatment shrinks the tumors to such an extent that they cannot be detected in follow-up scans, so they can 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 therapy, they generally cannot receive further radiation therapy in the same breast.”
And secondary tumors can come back more aggressively, Dr. Contreras said, because they can become resistant to previously used treatments like chemotherapy and radiation.
Secondary tumors can also spread to other areas like the lymph nodes, requiring more aggressive protocols.
However, thanks to targeted therapies, many women live several years, even decades, with advanced 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 lived with the disease for more than 10 years.