If you have
cancer, you may be unaware of the role that iron deficiency anemia frequently
plays in the disease. This type of anemia occurs when the body is unable to
produce enough hemoglobin, a substance found in red blood cells that transports
oxygen, due to a lack of iron. According to a study published in the journal
PLOS ONE in March 2015, people with iron deficiency anemia have a significantly
higher overall cancer risk than those who do not, and the risk of pancreatic,
kidney, liver, and bladder cancers is significantly increased even up to five
years after the iron deficiency is diagnosed.
On the other
hand, all cancer types are associated with an increased risk of developing iron-deficiency anemia, though the risk is higher in certain cancer types. And the
consequences of iron deficiency anemia can be especially severe in cancer
patients, potentially interfering with treatment and lowering survival chances.
Here's what
you need to know about detecting and treating iron deficiency anemia when you
have cancer, as well as how the two conditions are linked.
Causes of Iron Deficiency
According to
the American Cancer Society, the main causes of anemia in cancer patients are cancer itself, blood loss, nutritional deficiencies, major organ problems,
and sickle cell disease or thalassemia (inherited disorders in which the body
destroys too many red blood cells).
According to
Lanie K. Francis, MD, a hematologist and medical oncologist at UPMC Hillman
Cancer Center in Pittsburgh, the most common cause of iron deficiency anemia in
adults is blood loss — in either the GI tract or the genitourinary system.
People with cancers in "those regions that present with bleeding,"
she says, "are most at risk of iron deficiency anemia."
Causes of Iron Deficiency
According to
the American Cancer Society, the main causes of anemia in cancer patients are cancer itself, blood loss, nutritional deficiencies, major organ problems,
and sickle cell disease or thalassemia (inherited disorders in which the body
destroys too many red blood cells).
According to
Lanie K. Francis, MD, a hematologist and medical oncologist at UPMC Hillman
Cancer Center in Pittsburgh, the most common cause of iron deficiency anemia in
adults is blood loss — in either the GI tract or the genitourinary system.
People with cancers in "those regions that present with bleeding,"
she says, "are most at risk of iron deficiency anemia."
Iron Deficiency and Chemotherapy
Chemotherapy
is another factor that contributes to iron deficiency in cancer patients.
According to a 2015 study published in the journal Blood, 75 percent of people
undergoing chemotherapy for various cancer types were iron deficient, with 60
percent showing signs of absolute iron deficiency (see below). Chemotherapy can
cause iron deficiency due to decreased appetite and poor nutrition,
gastrointestinal mucosal damage that results in blood loss, or the release of
chemicals known as cytokines, according to the researchers.
Furthermore,
chemotherapy can result in pancytopenia, a condition in which many blood
components, including red cells, white cells, and platelets, are depleted.
Types of Iron Deficiency in Cancer
There are
two types of iron deficiency in cancer patients: absolute and functional.
The body
does not have an adequate supply of iron when suffering from absolute iron
deficiency. According to a study published in the Central European Journal of
Medicine in December 2015, absolute iron deficiency is usually caused by blood
loss, poor iron absorption, or both. As a result, colorectal cancer has an
especially high risk of absolute iron deficiency, but other cancers have risks
as well.
In
functional iron deficiency, the body has adequate iron stores — mostly in the
blood, liver, spleen, and bone marrow — but it can't use this iron properly for
a variety of biochemical reasons. Inflammation, which can be caused by cancer,
infection, chronic kidney disease, or other chronic diseases, as well as
certain drugs or nutritional deficiencies, such as a copper deficiency, are
common causes of functional iron deficiency.
What Do Anemia and Cancer Mean?
According to Francis, iron deficiency anemia "may be the red flag that leads a health care provider to search for cancer," because it is typically caused by blood loss, which occurs frequently in colon cancer and uterine cancer but less frequently in bladder cancer.
Iron
deficiency anemia, regardless of the cause, can make cancer treatment more
difficult. "If a patient has long-standing iron deficiency anemia prior to
the cancer diagnosis," Francis says, "it can weaken or decondition
them, making chemotherapy or other treatment difficult to tolerate."
According to
a study published in the Central European Journal of Medicine, anemia of any
cause is linked to decreased physical fitness and reported quality of life in
cancer patients. Anemia is also linked to a higher mortality rate in cancer
patients, though the article notes that it's unclear whether treating anemia improves
survival, implying that it could sometimes be a symptom rather than a cause of
deterioration.
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Having Yourself Tested and Treated
If you have
cancer, it is especially important to see your doctor and get tested for anemia
if you have symptoms such as fatigue, a fast heartbeat, shortness of breath or
difficulty breathing during physical activity, dizziness, chest pain, swelling
in your hands, or feet, or paleness of your skin, nail beds, mouth, or gums.
If a blood
test confirms that you have iron-deficiency anemia, your doctor may pursue one
of two potential (and complementary) courses of action: determining the source
of your deficiency and treating it directly.
To begin,
your doctor will most likely order additional tests to determine the cause of
your anemia. These tests may include determining your transferrin saturation
(TSAT), which indicates a functional iron deficiency, as well as your ferritin
level, which indicates absolute iron deficiency. According to Francis, the
"gold standard" test for confirming absolute iron deficiency is a
bone marrow biopsy — but this is rarely required.
If you're
losing blood due to cancer or another known cause, your healthcare team will
most likely already be attempting to stop any active bleeding, according to
Francis. However, if there is no known source of blood loss, your doctor will
most likely ask about any symptoms that may indicate blood loss and may test
your stool for blood using a fecal occult blood test (FOBT) or consider
ordering a colonoscopy.
Your doctor
may prescribe either oral iron supplements or intravenous (IV) iron to treat
your iron deficiency directly. If your anemia is particularly severe or sudden,
you may be given a red blood cell transfusion. Because a transfusion quickly
increases your hemoglobin level, it can be an important way to ensure that
enough oxygen reaches your vital organs.
In the long
run, it's also important to eat iron-rich foods like meat and fish, dark green
leafy vegetables, dried fruits, beans and other legumes, and enriched bread,
cereal, and pasta. When it comes to iron bioavailability and maximum iron
absorption from the diet, meat sources of iron tend to be the best choice.
"Treatment
of iron deficiency in cancer patients is the same as it is in the noncancer
population," Francis says. However, because the stakes are so much higher
when you have cancer, if you suspect you have iron-deficiency anemia, don't
wait to see your doctor for testing and treatment.
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