Metastasis Totally Explained

Everything about Metastasize totally explained

Metastasis (Greek: displacement, μετά=next + στάσις=placement, plural: metastases), sometimes abbreviated mets, is the spread of a disease from one organ or part to another non-adjacent organ or part. Only malignant tumor cells and infections have the capacity to metastasize. Cancer cells can "break away", "leak", or "spill" from a primary tumor, enter lymphatic and blood vessels, circulate through the bloodstream, and settle down to grow within normal tissues elsewhere in the body. Metastasis is one of three hallmarks of malignancy (contrast benign tumors). Most tumors and other neoplasms can metastasize, although in varying degrees (for example, glioma and basal cell carcinoma rarely metastasize).
   Cancer cells may spread to lymph nodes (regional lymph nodes) near the primary tumor. This is called nodal involvement, positive nodes, or regional disease. Localized spread to regional lymph nodes near the primary tumor isn't normally counted as metastasis, although this is a sign of worse prognosis.
   In addition to the above routes, metastasis may occur by direct seeding, for example, in the peritoneal cavity or pleural cavity.
   Cancer researchers studying the conditions necessary for cancer metastasis have discovered that one of the critical events required is the growth of a new network of blood vessels, called tumor angiogenesis. It has been found that angiogenesis inhibitors would therefore prevent the growth of metastases. Studies have shown that, if simple questioning doesn't reveal the cancer's source (coughing up blood -'probably lung', urinating blood - 'probably bladder'), complex imaging won't either. In some of these cases a primary may appear later.
   The use of immunohistochemistry has permitted pathologists to give an identity to many of these metastases. However, imaging of the indicated area only occasionally reveals a primary. In rare cases (for example, of melanoma), no primary tumor is found, even on autopsy. It is therefore thought that some primary tumors can regress completely, but leave their metastases behind.

Common sites of origin

Lung
Breast
Skin: Melanoma (other skin tumors rarely metastasize)
Colon
Kidney
Prostate
Pancreas

Diagnosis of primary and secondary tumors

The cells in a metastatic tumor resemble those in the primary tumor. Once the cancerous tissue is examined under a microscope to determine the cell type, a doctor can usually tell whether that type of cell is normally found in the part of the body from which the tissue sample was taken.
For instance, breast cancer cells look the same whether they're found in the breast or have spread to another part of the body. So, if a tissue sample taken from a tumor in the lung contains cells that look like breast cells, the doctor determines that the lung tumor is a secondary tumor. Still, the determination of the primary tumor can often be very difficult, and the pathologist may have to use several adjuvant techniques, such as immunohistochemistry, FISH (fluorescent in situ hybridization), and others. Despite the use of techniques, in some cases the primary tumor remains unidentified.
Metastatic cancers may be found at the same time as the primary tumor, or months or years later. When a second tumor is found in a patient that has been treated for cancer in the past, it's more often a metastasis than another primary tumor.

Treatments for metastatic cancer

Whether or not a cancer is local or has spread to other locations affects treatment and survival. If the cancer spreads to other tissues and organs, it may decrease a patient's likelihood of survival. However, there are some cancers (for example, leukemia, brain) that can kill without spreading at all.
When cancer has metastasized, it may be treated with radiosurgery, chemotherapy, radiation therapy, biological therapy, hormone therapy, surgery or a combination of these. The choice of treatment generally depends on the type of primary cancer, the size and location of the metastasis, the patient's age and general health, and the types of treatments used previously. In patients diagnosed with CUP, it's still possible to treat the disease even when the primary tumor can't be located.
The treatment options currently available are rarely able to cure metastatic cancer, though some tumors, such as testicular cancer, are usually still curable.

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