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What is Metastasized Cancer? Print E-mail
What is Metastasized Cancer?

Metastasis occurs when a cancer spreads from its original location to a non-adjacent organ or body part

If your doctor has informed you that your cancer has metastasized, you probably have many questions and concerns about your diagnosis, what treatments you are likely to receive, your prognosis, and what happens when treatment is completed.

Metastasis occurs when a cancer spreads from its original location to a non-adjacent organ or body part. When this happens, the cancer is still considered the same type of cancer as where it originated.

For example, if breast cancer spreads to the lung, the cancer in the lung is still considered breast cancer and is called metastatic breast cancer to the lung. The cancer cells in the lung will behave like the cells in the original breast cancer.

Cancer cells most often spread by traveling from the site of origin via the bloodstream or the lymphatic system or through both routes.

Symptoms of metastatic cancer depend upon the affected location and the size of the metastasis. Although pain in that area is possible, it is not necessarily the first symptom. Some patients don't have any symptoms, and their metastasis is found through tests done for other reasons.

Primary vs. Metastasized Cancer

If you have just been diagnosed with cancer, you may wonder how your doctor knows whether the tumor is the primary cancer (the site of the cancer’s origin) or a metastasized cancer. When your doctor initially biopsied the area in question, a pathologist reviewed the cells to determine whether the sample was benign or malignant. At the same time, the pathologist can most often tell where the cancer originated from certain characteristics of the cells. For instance, cells from breast cancer appear different from those from lung cancer. If your biopsy was from a concerning nodule in your lung, the pathologist will be able to see whether the cells are lung cancer cells or if they perhaps originated from another site, such as the kidney.

If you have been treated for cancer in the past, a tumor found at another site in your body is most likely a metastasis of your original cancer rather than a new primary tumor.

Common Sites of Metastatis

Certain locations are affected more than others because of how close they are located to the original cancer or the accessibility of the bloodstream or lymph channels. Cancer cells can separate from the primary site, and can then enter the bloodstream or lymph system and travel throughout the body. "Then the cancer may spread farther to other distant places," reports Tawee Tanvetyanon, MD, assistant member, Moffitt Cancer Center in Tampa, Florida. "Usually the farther it spreads, the harder the cancer is to treat."

Regarding the spread to distant locations, it is unclear why some cancers tend to spread to particular areas or organs. The most common distant places of metastasis for specific types of cancer are:

  • For breast cancer: bone, lung, liver, and brain
  • For colon cancer: liver, potentially lungs
  • For colorectal cancer: liver, lung, and brain
  • For kidney cancer: liver, bone, brain, lungs
  • For lung cancer: adrenal gland, liver, bone, brain
  • For melanoma (skin cancer): lung and brain
  • For prostate cancer: bone and lymph nodes
  • For stomach cancer: liver, ovaries (in women) 

Incidence rates vary according to the type of primary cancer.

Diagnosis and Treatment

Metastasized tumors are always associated with a primary cancer. A primary site is usually determined by having a pathologist evaluate a biopsy under a microscope and examining radiology data obtained from CT or CAT scans. Metastatic cancers might be found at the same time as the primary tumor, or months to years later.

When the origin cannot be determined, which is quite rare, it is referred to as cancer of unknown primary origin (CUP).

Metastases to a distant organ signifies a stage IV cancer (the last stage), which is when cancer has the greatest ability to spread. Generally speaking, metastasized cancers may be more aggressive, and the treatment approach differs markedly from that for localized tumors.

The type of treatment generally depends upon the type of primary cancer, the size and location of the metastasis, the patient's age and health, and the types of treatments used previously.

Treatments may include chemotherapy, targeted agents, radiation therapy, biological therapy, hormone therapy, surgery, or a combination of these. Targeted agents work specifically against mechanisms that drive cancer cells to grow and divide and are used as long as they are proven to be effective.


Treatment and survival rates are determined by whether or not a cancer is local or has spread to other locations. If the cancer spreads to other tissues and organs, it may decrease a patient's likelihood of survival.

"Metastatic disease carries a much more limited prognosis than localized disease in most cases," says Sumanta Kumar Pal, MD, assistant professor of Genitourinary Malignancies in the Department of Medical Oncology and Experimental Therapeutics at the City of Hope Comprehensive Cancer Center in Duarte, California. 

"In certain cancer types such as kidney cancer, prior to using targeted agents, survival was relatively limited to using either chemotherapy or agents that modulate the immune system," Dr. Pal continues. "With targeted agents, the prognosis has improved to a significant extent."

"A good number of people with metastatic cancers live pain-free for many years,” says Dr. Tanvetyanon. “This can result from diligent follow-ups and effective therapies. It is also true that some people with distant metastatic cancers have been cured of cancer."

Although most metastatic cancers are incurable, treatments are available to manage the disease, prolong survival, and improve your quality of life. However, frequent checkups are necessary after treatment to monitor for metastasis recurrence.