Specific metastasis pathways
As already mentioned, for certain primary tumors there are typical sites for developing metastases depending on the outflow of lymph and bloodstream. The surface characteristics of the cancer cells also determine the metastasis site, e.g. lung cancer or colon cancer cells occasionally metastasize into the adrenal gland, since they find similar tissue conditions there. In breast cancer patients, the first metastases are found in the regional lymph nodes of the armpits, and as the disease progresses, scattering can also be observed in the bones, liver, lungs, brain and skin.
Prostate carcinoma typically spreads to bones, lungs, liver and the meninges. In colorectal cancer, metastasis begins in the liver, lung and peritoneum and then progresses to the bones and possibly the ovaries. In lung cancer, metastases develop first in the brain and then in bones, liver and adrenal glands.
Therapy
The therapy of metastases is similar to that of the primary tumor, and always aims to remove or destroy the tumor. Depending on the location, size and differentiation of the metastasis, this is done by surgical removal of the affected tissue, chemotherapy or radiotherapy. If only neighboring lymph nodes are affected, a targeted removal of these and/or radiation can lead to a successful therapy.
Bone metastases are specifically attacked by radiation, and can also be prevented from growing by drugs that slow down bone growth. If metastases are known to occur in various organs or body compartments of a patient, treatment is carried out with a so-called systemic therapy, i.e. a more extensive therapy. In most cases, a so-called cytostatic drug is used for this purpose, i.e. a chemotherapy that can be adapted to specific tumor cells. In the case of cancers that grow in a hormone-dependent manner, such as breast and testicular tumors, additional suppression of the respective hormone can bring therapeutic success.
Prognosis
The prognosis for cancer patients who have already metastasized is not easy to make. It depends on the type and location of the primary tumor as well as the size, number and location of the metastases. A complete healing process can only be observed as long as the metastases and the primary tumor can be surgically removed without residue or destroyed by chemo- and/or radiotherapy.
Unfortunately, however, this is not possible in many cases because so-called micrometastases (incipient metastases of the smallest spatial extent) cannot be detected diagnostically and thus cannot be treated specifically. In these cases, the aim is to slow down the progression of the disease and reduce the symptoms, a so-called palliative therapy.
