Signs and Symptoms of a Cancer of Unknown Primary

The signs and symptoms of a cancer of unknown primary (CUP) vary depending on where it has spread. It’s important to note that the symptoms listed below aren’t caused just by CUP. In fact, they are more likely to be caused by something other than cancer. Still, if you have symptoms that suggest that something abnormal may be going on, see a doctor so that the cause can be evaluated and treated, if needed.

Some possible symptoms of CUP include:

Swollen, firm, non-tender lymph nodes

Normal lymph nodes are bean-sized collections of immune system cells located throughout the body. They help fight infections. Cancers often spread to the lymph nodes, which become swollen and firmer. When a person has an enlarged lymph node, they might notice a lump under the skin. Enlarged lymph nodes may be felt on the side of the neck, above the collarbone, under the arms, or in the groin area. Sometimes, a doctor notices them first during a routine checkup.

A feeling of “fullness” or a mass in the abdomen that can be felt

A mass in the abdomen (belly) may be felt as a swelling or firm area. This can be caused by cancer growing in the liver or less often, the spleen.

Sometimes the cancer cells grow on the surface of many organs in the abdomen. This may cause ascites, the buildup of fluid inside the abdomen. The fluid buildup can swell the abdomen. It can sometimes lead to a feeling of fullness or bloating.

Shortness of breath

Cancer that has spread to the lungs can cause shortness of breath. It can also be caused by the build-up of fluid and cancer cells in the space around the lungs (a pleural effusion).

Pain in the chest or abdomen

Pain in the chest or abdomen may be caused by cancer growing around nerves or by tumors pressing against internal organs.

Bone pain

Cancer that has spread to the bones can sometimes cause severe pain. Common areas of pain include the back and the legs and hips. But any bone can be affected. The bones may be weakened by the cancer’s spread and can break from minor injuries or even the normal stress of supporting the body’s weight. This can lead to a sudden severe pain or worsening of pain that was already there.

Skin tumors

Some cancers that start in internal organs can spread through the bloodstream to the skin. Because bumps in the skin are easily seen, skin metastases are sometimes the first sign of spread from a CUP.

Low red blood cell counts (anemia)

Cancer that started in the gastrointestinal system (such as esophagus, stomach, small intestines, or colon) can bleed. Often this occurs slowly, so the blood isn’t visible in the stool. Eventually, this can lead to low red blood cell counts. Having low red blood cell counts is called anemia.

Red blood cell counts can also become low if the cancer spreads to the bone marrow and crowds out the normal blood forming cells.

Weakness, fatigue, poor appetite, and weight loss

These symptoms are often seen with more advanced cancers. They may occur because the cancer has spread to specific organs or systems such as the bone marrow or digestive system. Some cancers also release substances into the bloodstream that can affect metabolism and cause these symptoms.

This is not a complete list of symptoms that might be caused by CUPs. It is important to remember that most of the symptoms above are more likely to be caused by conditions other than cancer. Still, if you have any of these problems, it’s important to see your doctor right away so the cause can be found and treated, if needed.