Breast cancer begins when cells in the breast grow abnormally and form a tumor. This growth can start in the milk ducts or milk-producing lobules. As these abnormal cells multiply, they can gain the ability to move beyond their original location. When breast cancer cells spread from the breast to other parts of the body, this process is known as metastasis.
Understanding Metastasis
Metastasis describes the process by which cancer cells detach from the primary tumor and travel to distant sites in the body. These cells can enter the body’s transportation systems, primarily the bloodstream or the lymphatic system.
The lymphatic system is a network of vessels and nodes that carry fluid and immune cells. Cancer cells can enter lymphatic vessels and travel to nearby lymph nodes, which act as filters. Similarly, cancer cells can invade blood vessels and be carried by the blood to various organs. While many traveling cancer cells may not survive, some can settle in a new location and form new tumors.
Common Initial Locations of Spread
The first place breast cancer commonly spreads is to nearby regional lymph nodes, such as those in the armpit (axillary lymph nodes) or around the collarbone. This spread to lymph nodes is often the earliest sign of cancer moving beyond its original site.
Beyond the regional lymph nodes, breast cancer most frequently spreads to distant sites like the bones, lungs, liver, and brain. Bones are a common distant site, affecting approximately 70% of individuals with metastatic breast cancer. The lungs and liver are also frequent targets. The brain is another potential site.
These organs are common targets because of their rich blood supply, which makes it easier for circulating cancer cells to settle there. For instance, blood passes through the lungs, making them a common destination for cancer cells. Similarly, the liver filters blood, providing an environment where cancer cells might establish new growths.
Symptoms of Distant Spread
When breast cancer spreads to distant organs, it can cause a range of symptoms depending on the affected area. If cancer reaches the bones, common symptoms include pain, particularly in the spine, ribs, pelvis, or long bones. This bone involvement can also lead to weakened bones that are more prone to fractures.
Spread to the lungs can manifest as a persistent cough, shortness of breath, or chest pain. Some individuals might also experience wheezing or recurring chest infections. In some cases, fluid can build up around the lungs, causing breathlessness.
Liver metastasis may cause symptoms such as pain on the right side of the abdomen, nausea, loss of appetite, or an overall feeling of being unwell. Yellowing of the skin and eyes, known as jaundice, can also occur. Sometimes, there may be no noticeable symptoms in the liver until the disease is advanced.
When breast cancer spreads to the brain, symptoms can include headaches that are persistent or worsening, changes in vision, seizures, or nausea and vomiting. Individuals might also experience changes in balance or coordination, numbness or weakness on one side of the body, or alterations in personality and memory.
Importance of Early Detection
Detecting breast cancer early is important for preventing or limiting metastasis. When breast cancer is found in its initial stages, treatment options are generally more effective. This early detection can improve survival rates.
Regular screenings play a crucial role in early detection, often identifying cancer before any symptoms appear. Common screening methods include mammograms, which use X-rays to create images of breast tissue. Clinical breast exams by a healthcare provider and breast self-awareness are important. Ongoing monitoring for individuals diagnosed with breast cancer helps to identify any potential spread promptly.