Symptoms of cancer of unknown primary

• Secondary cancer in the lung - You may have a cough that doesn’t go away, breathlessness or fluid collecting around the lungs (pleural effusion).  
• Secondary cancer in the bone - You may experience a dull, persistent pain in the bone that’s often worse at night. Sometimes if a bone is weakened by cancer it will break (fracture).
• Secondary cancer in the liver - Symptoms include swelling and discomfort in the tummy (abdomen), feeling sick and loss of appetite, yellowing of the skin and eyes (jaundice), and fluid collecting in the abdomen (ascites).
• Secondary cancer in the lymph nodes (glands) - Your lymph nodes may be swollen and feel hard or cause pain if they’re pressing on tissue or nerves nearby. The most common lymph nodes to be affected are the nodes in the neck, armpit, chest or groin. 

General symptoms

You may also have some general symptoms including:

• unexplained weight loss
• loss of appetite
• feeling extremely tired all the time
• looking pale, feeling tired and breathless due to a lack of red blood cells (anaemia).

All the symptoms mentioned here can be caused by conditions other than cancer, but it’s important to see your doctor and get them checked.