The signs and symptoms of many types of cancer can be subtle in nature and difficult to ascertain. Lung cancer is a very common disease in which symptoms can be elusive in nature, so much so that the condition may be difficult to diagnose in the early stages. Lung cancer, like many other forms of cancer, is best diagnosed in the early stages in order for effective treatment. As with other cancers, lung cancer left undiagnosed can quickly spread (or metastasize) to other areas of the body.  
Here are the main lung cancer symptoms that are often overlooked:

1. Back or shoulder pain
Shoulder or lower back pain are often associated with repetitive stress or sport’s injuries. However, both are also common yet surprising signs of lung cancer. Back or shoulder pain develops in lung cancer patients if a Pancoast tumor is present. A Pancoast tumor tends to develop in the upper portion of the lung and causes pain behind the ribs and vertebrae, which explains the feeling of pain in the back or shoulder areas.

2. Puffiness
When a lung cancer tumor grows, often deoxygenated blood transport through the body is stifled. In particular, lung cancer often blocks the superior vena cava, which is the main transport for returning deoxygenated blood to the heart. This blockage will often cause a buildup of excess fluids in areas like the face, neck, and arms. It may also cause chest skin to turn a bluish-red in color.

3. Fat fingertips
Lung cancer tumors, like many cancerous growths, may lead to hormonal imbalances within the body. Another often mystifying symptom of lung cancer is a fattening of the fingertips, which is caused when blood and fluid is forced and stored in the extremities (i.e., fingertips). This may cause a bulbous effect as well as abnormal curving of the finger nails

4. Anemia 
Anemia is often associated with lung cancer as it’s common for patients with this type of cancer to produce less healthy red blood cells as their cancer develops. Lack of red blood cells for oxygen transport will often lead to anemia in patients with symptoms of unexplained fatigue, muscle spasms, heart palpitations, and hypercalcemia, which causes excessive calcium in the blood. 

5. Gynecomastia
Specific to male lung cancer patients, gynecomastia is the development of excess breast tissue. This is often the result of large cell lung cancer tumors causing hormonal imbalances, and swelling in the chest tissues.