When lung cancer spreads to the bones, cancer cells from the original lung tumor establish new tumors within the skeletal system. This condition, known as bone metastasis, is common in advanced lung cancer. While this spread changes the approach to care, various strategies exist to manage symptoms and improve daily life.
How Lung Cancer Spreads to Bones
Cancer cells from a lung tumor can detach and travel through the body. These cells primarily use the bloodstream or the lymphatic system, a network of vessels that carry fluid and immune cells. Once in these circulatory systems, they can reach distant sites, including the bones.
Bones are a frequent destination for these cancer cells due to their rich blood supply. When these cells settle in bone tissue, they interact with the bone’s natural cells: osteoblasts (which build new bone) and osteoclasts (which break down old bone). This interaction often disrupts the normal balance of bone remodeling, leading to excessive bone breakdown or, less commonly, excessive bone formation.
Recognizing the Signs
Lung cancer that has spread to the bones often presents with several symptoms. The most common is bone pain, which can be a dull ache that intensifies. This pain may worsen at night or with movement and often occurs in areas like the spine, ribs, pelvis, or long bones of the arms and legs.
Bones weakened by cancer are more susceptible to fractures, known as pathological fractures. These breaks can occur with minimal trauma or spontaneously, causing sudden, sharp pain. If cancer affects the spine, it can compress the spinal cord or nerves, leading to weakness, numbness, or tingling in the limbs, and issues with bowel or bladder control. Additionally, bone destruction can release high levels of calcium into the bloodstream, a condition called hypercalcemia. Symptoms of hypercalcemia include fatigue, nausea, constipation, increased thirst, and confusion.
Diagnosing Bone Metastases
Identifying bone metastases involves a combination of imaging techniques and laboratory tests. Imaging is crucial for visualizing bone changes. Standard X-rays can show areas of bone destruction, appearing as dark spots, though they may not detect metastases in early stages.
Bone scans, which involve injecting a small amount of radioactive tracer, can detect bone changes earlier than X-rays and provide an overview of the entire skeleton. More detailed images come from CT scans, which provide cross-sectional views, and MRI scans, useful for evaluating soft tissues like bone marrow and detecting spinal cord compression. PET scans, often combined with CT (PET-CT), use a radioactive sugar that cancer cells absorb, helping identify metastatic sites throughout the body. Blood tests can offer clues, with elevated levels of calcium or an enzyme called alkaline phosphatase sometimes indicating bone involvement, although these markers alone are not definitive for diagnosis.
Managing Bone Metastases
Managing lung cancer that has spread to the bones focuses on alleviating symptoms, preventing complications, and supporting well-being. Pain control is a main goal, often achieved through various pain medications, from over-the-counter to prescription drugs. Radiation therapy is often used to target specific areas of bone pain, shrinking tumors and providing significant relief, sometimes in a single session.
Bone-modifying agents, such as bisphosphonates and denosumab, strengthen bones and reduce the risk of fractures and high calcium levels. These agents work by slowing down the bone breakdown process. Sometimes, surgical interventions may be considered. These procedures can stabilize bones at risk of fracture, repair existing fractures, or relieve pressure on the spinal cord caused by tumors. Management is tailored to each individual, considering the spread, symptoms, and overall health, aiming to improve comfort and quality of life.