Code 7: Distant

  • Tumor cells have broken away from the primary tumor, traveled to other part of the body, and started to grow at the new location
  • Also referred to as remote, diffuse, disseminated, metastatic, or secondary disease
  • No continuous trail of tumors cells between primary site and distant site (discontinuous)
  • Common sites of distant metastases are liver, lung, brain, and bones
    • These organs receive rich blood flow from all parts of the body and thus are a target for distant metastases

Types of distant routes of metastasis

  • Hematogenous spread (via the blood)
  • Lymphatic spread (via lymphatic system, including to distant lymph nodes)
  • Implantation via fluids in bodily cavities
  • Extension from the primary organ beyond adjacent tissue into the next organ

Illustration showing distant metastases where tumor cells have broken away from the primary tumor and travelled through the pleura into nerves to other parts of the body.

Illustration showing hematogenous or blood-borne metastases where invasion of blood vessels within the primary organ allows escape of tumor cells or tumor emboli which are transported through blood vessels to another part of the body (second site) where it lodges in a capillary or arteriole.

Source: Images adapted from illustrations by Brian Shellito of Scientific American, as printed in Cancer in Michigan, The Detroit News, Nov. 1-2, 1998.

  • Hematogenous or blood-borne metastases

Invasion of blood vessels within the primary tumor allows escape of tumor cells or tumor emboli which are transported through the blood stream to another part of the body where it lodges in a capillary or arteriole. At that point the tumor penetrates the vessel wall and grows into the

Illustration showing distant lymph node involvement where invasion of blood vessels within the primary organ travel in lymph channels beyond the first (regional) drainage area to lymph nodes identified as being remote (distant) from the primary site.

Source: Adapted from an illustration by Brian Shellito of Scientific American, as printed in Cancer in Michigan, The Detroit News, Nov. 1-2, 1998.

  • Lymph channels beyond the first (regional) drainage area to lymph nodes are identified as being remote (distant) from the primary site.
  • Tumor cells can be filtered, trapped and begin to grow in any lymph nodes in the body.

Travel in lymph channels beyond the first (regional) drainage area. Tumor cells can be filtered, trapped and begin to grow in any lymph nodes in the body.

Source: Young JL Jr, Roffers SD, Ries LAG, Fritz AG, Hurlbut AA (eds). SEER Summary Staging Manual - 2000: Codes and Coding Instructions, National Cancer Institute, NIH Pub. No. 01-4969, Bethesda, MD, 2001.

Illustration showing implantation metastases where malignant cells rupture the surface of the primary organ and are released into the thoracic or peritoneal cavity. They float in fluids in the body cavity and begin to grow on any tissue in other parts of the body reached by the fluid.

Source: Adapted from an illustration by Brian Shellito of Scientific American, as printed in Cancer in Michigan, The Detroit News, Nov. 1-2, 1998.

  • Spread through fluids in a body cavity
    • Example: malignant cells rupture the surface of the primary tumor and are released into the thoracic or peritoneal cavity. They float in the fluid and begin to grow on any tissue reached by the fluid.
  • Implantation or seeding metastases
    • Some tumors form large quantities of fluid called ascites that can be removed, but the fluid rapidly re-accumulates. However, the presence of fluid or ascites does not automatically indicate dissemination. There must be cytologic evidence of malignant cells.

Left Image: Spread through fluids in a body cavity. Example: malignant cells rupture the surface of the primary tumor and are released into the thoracic or peritoneal cavity. They float in the fluid and can land on and begin to grow on any tissue reached by the fluid. This type of spread is also called implantation or seeding metastases. Some tumors form large quantities of fluid called ascites that can be removed, but the fluid rapidly re-accumulates. However, the presence of fluid or ascites does not automatically indicate dissemination. There must be cytologic evidence of malignant cells. Right Image: Hematogenous or blood-borne metastases. Invasion of blood vessels within the primary tumor (veins are more susceptible to invasion than thicker-walled arteries) allows escape of tumor cells or tumor emboli which are transported through the blood stream to another part of the body where it lodges in a capillary or arteriole. At that point the tumor penetrates the vessel wall and grows back into the surrounding tissue.

Source: Young JL Jr, Roffers SD, Ries LAG, Fritz AG, Hurlbut AA (eds). SEER Summary Staging Manual - 2000: Codes and Coding Instructions, National Cancer Institute, NIH Pub. No. 01-4969, Bethesda, MD, 2001.

Updated: November 5, 2024