Metastatic carcinoma

December 4, 2023

Metastatic carcinoma refers to cancer that has spread from its original (primary) site to other parts of the body. The term carcinoma specifically refers to a type of cancer that begins in the epithelial cells, which are the cells that line the organs and tissues of the body. For example, if someone has metastatic carcinoma of the breast, it means that cancer cells from the original breast tumor have spread to other organs or tissues in the body.

Cancer cells can break away from the primary tumor and travel through the bloodstream or lymphatic system to distant organs or tissues, where they can form new tumors. The new tumors are called metastases. Pathologists use the terms lymphovascular invasion and angiolymphatic invasion to describe cancer cells inside of a blood vessel or lymphatic space.

How do pathologists identify the original (primary) tumor?

Identifying the primary tumor in cases of metastatic carcinoma can be challenging, but pathologists use a combination of techniques and tests to determine the origin of the cancer.

Here are some common methods:

  • Histopathology: Pathologists examine the morphology (structure and appearance) of the cancer cells under a microscope. Different types of cancers have distinct cellular features, and these features can provide clues about the origin of the tumor.
  • Immunohistochemistry (IHC): Immunohistochemistry involves using antibodies that react with specific proteins present in different types of cells. By applying these antibodies to the tissue sample, pathologists can identify the presence or absence of certain proteins, helping to narrow down the possible origin of the cancer.
  • Molecular and genetic tests: Advances in molecular and genetic testing allow pathologists to analyze the DNA, RNA, and protein expression patterns in cancer cells. Molecular profiling can provide information about the genetic mutations or alterations that are characteristic of certain types of cancer. These tests include next-generation sequencing (NGS), fluorescence in situ hybridization (FISH), and polymerase chain reaction (PCR).
  • Clinical history and imaging studies: The patient’s clinical history, including symptoms, prior medical conditions, and imaging studies, can provide important context. Imaging studies, such as CT scans, MRIs, and PET scans, can help identify the location and extent of metastases and the original (primary) site of origin.

Despite these methods, determining the primary tumor site may not always be straightforward, especially in cases where metastasis is the first manifestation of cancer. In some instances, the primary tumor remains unidentified, and the cancer is classified as a “cancer of unknown primary” (CUP).

How is metastatic carcinoma treated?

Metastatic carcinoma is considered advanced cancer, and it is generally more challenging to treat than cancer that is localized to its original site. Treatment for metastatic carcinoma often involves a combination of therapies, such as chemotherapy, radiation therapy, targeted therapies, and sometimes surgery, depending on the specific characteristics of the cancer and its location. The goal of treatment is typically to control the spread of the cancer, alleviate symptoms, and improve the patient’s quality of life.

About this article

Doctors wrote this article to assist you in reading and comprehending your pathology report. Feel free to reach out to us with any questions about this article or your pathology report. To get a comprehensive introduction to your pathology report, read this article.

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