Is a Persistent Low-Grade Fever a Symptom of Cancer?

A fever is a common symptom related to many conditions, most of which are benign. An increase in body temperature is most often a biological response to a viral or bacterial infection (like the flu or strep throat). Occasionally, something other than infection can cause your fever.

A person is generally considered to have a fever when they have a temperature of 100.4°F or greater. Most experts define a low-grade fever as a temperature that falls between 99.5°F and 100.3°F. A high-grade fever is a body temperature greater than 103°F. Hyperpyrexia is a fever higher than 106.7°F.

With infection, your body raises its temperature to help destroy the invading germs. But what if you are not fighting off a cold? In rare cases, a persistent and otherwise unexplained fever ​can be a symptom of cancer. ​​Cancer is estimated to cause approximately 18% of fevers of unknown origins (FUO).

This article explains fevers related to cancer, the associated symptoms, and some other conditions that may cause low-grade fevers.

Cancers That Cause Fevers

Sometimes cancer can cause fever when there is not an active infection in the body. These are often called "tumor fevers." They can also be called neoplastic fevers. Certain types of cancer are more commonly known to cause fevers.

Leukemia

Leukemia is a cancer of the tissues that create blood cells. Unexplained fevers can be one of the symptoms of leukemia.

Some leukemias lower your white blood cell count. With fewer white blood cells, your immune system is weakened. This may make infections and fevers more common.

In some cases, cancer cells can release signals to the body to raise your body temperature and cause fevers. Cancer fevers do not always follow the same pattern from person to person. The frequency of cancer fevers has not been well studied in leukemia.

However, fevers are usually not an isolated symptom of leukemia. Other possible symptoms include fatigue, enlarged lymph nodes, unexplained bruising, body pains, and weight loss.

Lymphoma

Lymphoma is a cancer of the lymphatic system (which is part of the immune system). One type is called Hodgkin lymphoma, and the other types are called non-Hodgkin lymphomas.

Hodgkin lymphoma can present with fevers in about 25% of people. Fevers, night sweats, and weight loss are grouped and called "B symptoms" in people with this cancer.

Some other symptoms of lymphoma include swollen lymph nodes, loss of appetite, fatigue, and shortness of breath.

Kidney Cancer

Kidney cancer sometimes called renal cell carcinoma (RCC), is cancer that forms in the very small tubes of the kidneys where the blood is filtered and waste products are removed.

About 20% of people with kidney cancer have fevers related to their cancer.

Some additional symptoms of kidney cancer include blood in the urine (hematuria), low back pain, fatigue, low red blood cell levels (anemia), and unintentional weight loss.

Liver Cancer

Liver cancer sometimes, called hepatocellular carcinoma (HCC), is cancer that forms in the cells of the liver.

Liver cancer is very rare, and fevers as an early symptom are even rarer. A 2016 study found that over 10 years, only 63 out of 363 people had fevers as the first symptom of liver cancer.

Some possible symptoms of liver cancer include unintentional weight loss, nausea, vomiting, feeling very full after eating, itching, or yellowing of the skin or eyes. Abdominal pain, swelling, and extra fluid can also be symptoms of this disease.

Ovarian Cancer

Ovarian cancer is cancer that typically begins in the ovaries (part of the female reproductive system).

Data is not widely available on the frequency of fever for people with ovarian cancer.

Some symptoms of ovarian cancer include abdominal bloating, pain, fullness, or upset stomach. Fatigue, constipation, and back pain can also be symptoms of ovarian cancer in some women.

Signs and Symptoms

The key sign of a cancer-related fever is that it is persistent—meaning it lasts longer than three days. It can be either a low- or high-grade fever. Other symptoms can accompany a fever, or it can occur without other symptoms.

Keep an eye on your temperature regularly by using a thermometer. Even if over-the-counter (OTC) fever reducers like acetaminophen or ibuprofen relieve your fever, it is still critical to see your healthcare provider if the fever lasts for more than three days.

Other Causes of Fevers

Fever as a sign of cancer is rare. Many things unrelated to cancer can lead to fevers. The most common cause of fever is an infection. Viruses, bacteria, parasites, and other pathogens commonly result in fevers as the body works to fight the infection. There are also some non-infectious causes of fevers. Over 200 non-infectious causes of fevers have been identified.

Some potential causes of fevers include:

• Respiratory infections such as colds, flu-like illnesses, bronchitis, pneumonia, or tuberculosis (TB)
• Urinary tract infections (UTIs)
• Gastrointestinal infections, including gastroenteritis (“stomach flu”)
• Autoimmune or inflammatory disorders such as arthritis, lupus, and multiple sclerosis (MS)
• Medicines such as antibiotics, antihistamines, seizure medicines, and vaccines
  

At Your Appointment

Since many conditions can cause unexplained fevers, your healthcare provider will likely ask many questions to help make an accurate diagnosis. Be prepared to answer the following:

• How long have you had a fever?
• How often do you have a fever?
• Do you notice your fevers more at night?
• Do you have any other symptoms?
• What medications are you taking?
• Do you have any diseases or health conditions?
  
• Do you have a dental abscess or other dental problems that may indicate an infection?
• Have you traveled to any other countries within the last few months?

Your healthcare provider may decide to do a few routine tests to help pinpoint the source of your fever. These might include:

• Complete blood count (CBC), a blood test that measures your blood cells
• Comprehensive metabolic panel, a blood test that looks at seven different substances in the blood, including blood urea nitrogen (BUN), carbon dioxide, creatinine, glucose, serum chloride, serum potassium, and serum sodium, as well as liver function tests.
• Urinalysis to rule out a urinary tract infection

Summary

Rarely, unexplained fevers may be a symptom of cancer. For example, leukemia and lymphoma are two types of cancer that can present with fevers. Most commonly, though, fevers indicate an infection.

A Word From Verywell

Keep in mind that a fever is a very general, vague symptom. It is not a red flag, but it does indicate something is going on in your body.

If you have had a fever for more than a few days, it is a good idea to see your healthcare provider. They will run specific medical tests that can help pinpoint the source of the fever.