lung metastasis
Meaning of lung metastasis: Cancer that has traveled to the lung from somewhere else, keeping the identity of the organ it started in.
Definition of lung metastasis
A lung metastasis is a tumor deposit in the lung formed by cancer cells that traveled there from a primary tumor elsewhere in the body. Under the microscope the cells still resemble the tissue they came from, so breast cancer that reaches the lung remains breast cancer and is treated as such. The lung is among the commonest destinations for spread.
Why does the lung collect so many deposits?
Every drop of blood returning from the body passes through the lungs before it goes anywhere else. The vessels there branch down to capillaries narrower than a clump of tumor cells, so travelling cells are filtered out and held. Anything that reaches the bloodstream therefore gets an early opportunity to lodge in the lung. Tumors that spread this way most often include those of the breast, bowel, kidney, testis, bone, and melanoma of the skin.
How is it different from lung cancer?
| Lung metastasis | Primary lung cancer | |
|---|---|---|
| Where it began | Another organ | The lung itself |
| What the cells look like | Like the original organ | Like lung tissue |
| Appearance on a scan | Often several round nodules in both lungs | Usually one mass, often central |
| Treatment follows | The original cancer | Protocols for lung cancer |
How is it found?
Most deposits cause nothing at all early on and turn up on a scan arranged for another reason or as part of follow up. Larger or more numerous ones bring a persistent cough, breathlessness, chest pain, or blood in the sputum. Fluid may gather between the lung and the chest wall. When someone has a known cancer, the appearance and distribution on imaging are often enough, though a needle sample is taken when the picture is unclear or when a second, separate cancer is possible.
What does it mean for treatment?
Spread to the lung usually places a cancer at its most advanced stage, and treatment is aimed at the whole body rather than one spot. There is an important exception. When only a few deposits exist and the original cancer is controlled, removing them surgically or targeting them with focused radiation can achieve long survival, an approach used most in sarcoma, bowel and kidney cancer.
Also known as
Used in a sentence
Follow-up imaging showed several rounded lung metastases consistent with the known primary tumor.
Good to know
A lung metastasis is not lung cancer, and the distinction decides treatment, because the drugs chosen follow the tissue the cancer started in rather than the organ it has reached.
Word origin
Where “lung metastasis” comes from
Metastasis comes from the Greek meta, meaning change, and stasis, a standing, together describing a change of position.