Cancer is an overgrowth of tissue that occurs in any part of the body when cells lose their capacity to control their division. They become immortal and grow very rapidly. In their advance, cancer cells start losing their properties and become very different from healthy cells. One of the properties they lose is adherence to tissues, so they start migrating to other places. That is what happens in cancer metastasis.
Lung cancer divides into small cell and non-small cell lung cancer. Each one has its own properties, and some of them are more likely to end up in metastasis. In this article, we’re going through lung cancer’s metastasis and what to expect about this disease.
Lung Cancer Metastasis
Lung cancer metastasis is a very complex process. As noted above, one of the first changes in cancer cells that lead to metastasis is a reduction of cell adherence. These cells are no longer anchored to their surrounding tissue, so they can easily migrate to other tissues.
Many types of lung cancer are detected only when spread to other organs has already occurred. This will be stage IV lung cancer. A stage III lung cancer is also common at the moment of the diagnosis, and this type has spread to the lymph nodes around the tumor. Either way, a complete evaluation is often necessary to rule out spread to distant sites.
The most common metastasis sites after primary lung cancer are the brain, the adrenal glands, and the bones. Different subtypes of lung cancer can spread to other parts of the body. For example, small-cell lung carcinoma commonly spreads to the liver. Adenocarcinoma of the lungs is likely to spread to the brain, especially if they have a mutation in the epidermal growth factor receptor.
The process of migration to other tissues follows this route:
- Tumor growth and cell migration: As noted above, as the tumor grows, its cells become different from the rest and lose adhesion. Cell migration starts, first locally.
- Vascular and lymphatic invasion: At a given moment, cells without adherence properties reach the lymphatics or blood vessels and start circulating throughout the body.
- Extravasation: In this step, cancer cells in lymphatics and blood vessels go through the epithelial tissue and enter a new organ.
- Metastatic focus: In this new organ, cancer cells need to recruit blood vessels and establish themselves to start growing. When they do, a new metastatic focus is created.
Small cell lung cancer, also known as oat cell cancer, is the most common type of metastatic lung cancer. This type grows very rapidly and without giving out symptoms. It usually does not give enough time to diagnose the disease, and 70% of cases are already spread at the moment of diagnosis.
Lung Cancer Metastasis Signs and Symptoms
The symptoms of lung cancer metastasis are initially the same as primary cancer. They include shortness of breath, cough, hemoptysis, weight loss, and chest pain. But after a distant spread has occurred, new symptoms are included depending on the site of metastasis.
For example:
- In brain metastasis: Neurologic signs and symptoms start showing up, including headaches or blurred vision. Patients may begin feeling weakened and dizzy or start having balance problems. Seizures are also common in distant spread to the brain.
- In liver metastasis: Hepatitis-like symptoms are common in these cases, especially jaundice (a yellowish coloration of the skin). Abdominal pain is found when there are multiple metastasis foci. When the liver function starts to suffer, the organ stops creating essential proteins, and the abdomen begins to swell.
- In bone metastasis: The bone is very susceptible to losing its mineralization, and the effects are similar to those experienced in osteoporosis. Patients are more likely to endure fractures, and bone pain is also common. In some cases, the vertebrae in the spine start to lose their supportive function, leading to spinal cord compression.
- In metastasis to the adrenal glands: These glands synthesize adrenaline, cortisol, and other hormones associated with stress. This increases the patient’s metabolic rate and causes weight loss. Vomiting and nausea are also very common, usually showing up with abdominal pain. Patients often feel very tired and weak.
IF you’re experiencing one of these symptoms, it doesn’t necessarily mean that you have bone cancer and metastasis. Talk to your doctor if you’re worried about your health to get a complete assessment and recommendations adapted to you.
Treatment For Metastatic Lung Cancer
The treatment of lung cancer and metastasis is personalized and different from one patient and the other. When patients are already in stage-4 cancer, achieving a complete cure of the disease is very difficult. Surgery won’t be enough because even if we take out the primary tumor in the lungs, one or many metastases can be found in other parts. There are probably multiple distant metastasis growing, and we can’t see them yet. So, doctors typically use different methods to attack cancer:
- Chemotherapy: It is a standard treatment for metastatic lung cancer. It is a toxic substance that only activates in dividing cells. Since cancer cells have an accelerated dividing rate, they are more likely to be affected. However, chemotherapy can also affect healthy tissue.
- Radiation therapy: They are radiation waves applied directly to the affected area. They have a localized action against cancer and are explicitly directed to the problem area.
- Targeted therapy: This type of therapy is similar to chemotherapy, but it uses certain metabolic properties of cancer to achieve a more targeted effect. You could benefit from this type of treatment depending on the type of cancer and the metabolic properties of cancer cells.
- Immunotherapy: This type of therapy is an immune booster that helps your own immune system to detect and fight cancer more accurately.
Prognosis
In general, metastatic lung cancer has a very poor prognosis. This is very late-stage cancer, and even with the appropriate treatment, the life expectancy can be relatively low. The survival rate of metastatic lung cancer depends on the type of spread.
In distant spread (metastasis to other organs), the 5-year survival rate is 5.8%. If you have a regional spread in the thorax but no distant spread, this number increases to 32%. And if you only have localized spread in the lungs, the 5-year survival rate is 59%.
References:
National Cancer Institute. Cancer stat facts: Lung and bronchus cancer.
Popper, H. H. (2016). Progression and metastasis of lung cancer. Cancer and Metastasis Reviews, 35(1), 75-91.
Riihimäki, M., Hemminki, A., Fallah, M., Thomsen, H., Sundquist, K., Sundquist, J., & Hemminki, K. (2014). Metastatic sites and survival in lung cancer. Lung cancer, 86(1), 78-84.
