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Data from breast cancer survivors
showed that the cancer’s subtype and age at diagnosis affect the
risk for developing a new type of cancer.
The Challenge
Invasive breast cancer is the most commonly diagnosed cancer among
women in the United States. In 2019, there were more than 3.9
million survivors of breast cancer in the US. With improvements in
the treatment for breast cancer and the increase in the US aging
population, the number of breast cancer survivors is expected to
increase. Plus, most of those survivors live for many years after
their diagnosis. So, it’s more important than ever to take steps to
keep improving quality of life after diagnosis and treatment of
breast cancer.
One issue affecting breast cancer survivors is the risk of
developing a new type of cancer (called a subsequent primary cancer
or second cancer). Compared to the general population, breast cancer
survivors have a 17% higher risk of developing a new cancer.
However, this increased risk is not the same for all breast cancer
survivors. Studies have shown that the level of risk for developing
a new type of cancer depends on the:
Age at diagnosis of the first breast cancer
Treatments received: radiotherapy, chemotherapy, and/or hormonal
therapy
Lifestyle factors, such as using tobacco and having obesity
Genetic susceptibility
Subtype of breast cancer that was diagnosed
How these factors interact and contribute to risk of developing a
specific type of subsequent primary cancer is not well understood
and needs more study.
The Research
A group of researchers from the American Cancer Society (ACS),
Dana-Farber Cancer Institute, Mayo Clinic, and Institute for Health
& Equity at the Medical College of Wisconsin, recently published
their findings after studying the risk of 26 subsequent primary
cancers among female breast cancer survivors based on their age when
first diagnosed and the cancer’s hormone receptor status.
“Most women live decades after being diagnosed with breast cancer,
but some women may develop a new primary cancer years after
successful treatment. Currently, there’s limited knowledge about the
factors associated with a higher or lower risk for new primary
cancers specific to breast cancer survivors, and there’s no
established tool that predicts an individual’s risk of developing a
new cancer. In this study, we found that the risk of developing a
new primary cancer varies by the subtype of breast cancer a woman
has as well as the age she was when she was first diagnosed with
breast cancer. This result both highlights the need for tailored
recommendations for preventing and screening for new primary cancers
in breast cancer survivors based on their specific, personal risks
and provides information to help establish such guidelines.”
Hyuna Sung, PhD
American Cancer Society
Surveillance & Health Equity Science
Their study, led by ACS researcher Hyuna Sung, PhD, looked at data
for women who were first diagnosed with invasive breast cancer
between 1992 and 2015 and who survived for a year or longer. This
included 431,222 women ages 20 to 84 years.
To evaluate women’s risks, they compared the risk of developing
subsequent primary cancers among survivors versus the risk expected
in the general population of the same age and race.
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Most common subsequent cancers. Sung
and her colleagues found that regardless of a woman’s breast cancer
hormone receptor status, survivors were more likely than the general
population to be diagnosed with 7 types of cancers:
Acute nonlymphocytic leukemia (ANLL)
Breast cancer (This is a second breast cancer—different from the
first cancer coming back.)
Colon cancer
Endometrial Cancer
Lung cancer
Oral cavity/pharynx cancer
Sarcoma
How hormone status and age affect
risk. The researchers found that compared to the general public,
breast cancer survivors had a greater risk of developing a
subsequent primary cancer when their breast cancer had been:
HR-negative (44% higher risk) than those with an HR-positive cancer
(20% higher risk). Those with HR-negative cancers were more likely
to develop ANLL and cancers of the peritoneum, breast, ovary, and
lung.
Diagnosed when they were between 20
and 49 years of age (70% higher risk for HR-positive and 124% higher
risk for HR-negative) than for those diagnosed between the ages of
50 to 84 (11% higher risk for HR-positive and 22% higher risk for
HR-negative)
Subsequent primary breast cancers. 1 in 20 survivors developed a new
primary breast cancer, with 70% occurring in the other breast (contralateral).
Cancer types linked with specific risks:
Only women with a history of an HR-positive breast cancer had higher
risks for cancers of the thyroid, small intestine, pancreas, and
bladder and melanoma. Risks varied based on the woman’s age at
diagnosis.
Only women with a history of an HR-negative breast cancer had higher
risks for cancers in the esophagus, ovary, and peritoneum. Risks
varied based on the woman’s age at diagnosis. For instance, women
with HR-negative breast cancer also had a higher risk for ovarian
cancer when their cancer was diagnosed before age 40.
Why It Matters
These findings suggest that the risk of breast cancer survivors
developing a subsequent primary cancer differs greatly based on the
initial HR subtype and a woman’s age at diagnosis. That knowledge
can be used to develop survivorship care plans with more targeted
approaches for cancer prevention and early detection, which can help
ease the burden of new cancers among breast cancer survivors.
Taken from the American Cancer society website
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