ABC Medical Center > Diseases > Carcinoma of Unknown Primary

What is carcinoma of unknown primary?

23 January 2026

This is a medical term established when it is not possible to determine the initial location of the cancer—that is, the place where it started. It is also called occult primary cancer because only the cancerous cellular material that has spread to various body areas can be identified, but the primary tumor cannot be found due to various causes, such as:

  • The original tumor was so small that it was impossible to detect in imaging studies.
  • The immune system eliminated the original tumor.
  • Accidental removal of the tumor in a surgical procedure performed for another condition.

As in any type of cancer, carcinoma of unknown primary manifests due to a genetic mutation in the cells, which become abnormal and begin to multiply uncontrollably, accumulating and forming tumors susceptible to metastasizing and spreading to other body areas.

Furthermore, various potential risks for developing carcinoma of unknown primary have been identified, including:

  • Being over 60 years old.
  • Family members who have had cancer of the:
    • Lung.
    • Kidney.
    • Colon.

Signs and symptoms Carcinoma of Unknown Primary

The symptoms depend on the damaged body area, but generally include:

  • A palpable lump beneath the skin.
  • Painful episodes.
  • Changes in bowel habits:
    • Diarrhea.
    • Constipation.
  • Frequent urination.
  • Bouts of coughing.
  • High temperature (fever).
  • Night sweats.
  • Weight loss.

Diagnosis and treatment Carcinoma of Unknown Primary

The doctor will analyze your symptoms and clinical history, then perform a physical examination and request various studies such as:

  • Blood analysis.
  • X-rays.
  • Computed Tomography (CT) scan.
  • Magnetic Resonance Imaging (MRI).
  • Tissue Biopsy.

The treatment to follow will depend on the particular case, the size, and the stage of cancer advancement, but it generally includes:

  • Surgery.
  • Chemotherapy.
  • Radiation therapy.

Our Cancer Center, since its inauguration in 2009, offers chemotherapy and radiation therapy treatments on par with the best medical centers in the world through a comprehensive care model for the oncology patient.

Related centers and departments Carcinoma of Unknown Primary

Cancer Center
High Specialty Surgery Center
Radiology and Molecular Imaging
Clinical Laboratory

Sources:

  • radiologyinfo.org
  • cancer.org
  • cancer.net
  • cancer.gov
  • medlineplus.gov
  • msdmanuals.com
  • mayoclinic.org
  • medigraphic.com
  • González EC, Oliva GJP, Martínez RA, et al. Tomografía por emisión de positrones con 18F-fluordeoxiglucosa-tomografía computarizada en el diagnóstico del tumor primario de origen desconocido. Revista Habanera de Ciencias Médicas. 2019;18(6):873-885.
  • Vargas CDA. Carcinoma de sitio primario desconocido. Rev Med Cos Cen. 2016;73(620):583-586.
  • Gallegos HJF. Metástasis ganglionares cervicales de carcinoma epidermoide con tumor primario desconocido. Abordaje diagnóstico terapéutico actual. An Med Asoc Med Hosp ABC. 2016;61(1):25-32.
  • Serra VMÁ, Delgado AR. Carcinoma escamoso metastásico primario de origen desconocido. Presentación de un caso. Finlay. 2012;2(4):236-242.

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