Skip to Content

Cancer of Unknown Primary

Our Approach

At MD Anderson’s Gastrointestinal Center, we have the depth of expertise to provide customized expert treatment for each patient with cancer of unknown primary (CUP). Because MD Anderson is one of the most active cancer centers in the nation, we see a greater number of patients with CUP than most other centers. This gives us a level of experience that translates to exceptional care.  

Our experts work together in specialized teams that focus an incredible level of knowledge on you. Using the latest, most advanced technology, MD Anderson’s specialized pathologists concentrate extraordinary skill on diagnosing the origin of cancer of unknown primary.

Advanced Treatment, Range of Support

If the site of origin of cancer of unknown primary is found, MD Anderson offers a full range of the most advanced treatments for every diagnosis. Depending on the type of cancer, these may include proton therapy, targeted therapies, surgery and others. As one of the world’s leading cancer centers, we offer a range of clinical trials of new therapies. 

And because we know CUP can take a toll on you and your family’s quality of life, we provide a range of support and wellness services to help you live your life to the fullest. This includes specially trained psychologists and a supportive care team who know what you are going through and can help.

If you have CUP, it is important to be seen by expert doctors. We can help. Call 1-877-632-6789 to make an appointment or request an appointment online.

Why Choose MD Anderson?

  • Medical oncology and pathology experts with significant experience in evaluating cancer of unknown primary
  • Most-advanced diagnostic methods to pinpoint origin, including leading-edge CT scans and other imaging methods
  • Comprehensive range of renowned specialists to treat cancer when site of origin is found
  • Advanced CUP treatments including proton therapy, targeted therapies and surgery
  • Clinical trials (research studies) of new therapies

CUP Knowledge Center

Treatment at MD Anderson

Cancers of unknown primary are treated in our: 

Gastrointestinal Center by our expert team

Find Your MD Anderson Location


Cancer of Unknown Primary Facts

Cancer of unknown primary has metastasized (spread) from another part of the body. The place where it began, also called the primary site, is unknown. The exact number of cases of CUP is not known, but it is estimated to be about 2% to 5% of cancers diagnosed in the United States. It is becoming less common because of better methods and technology to diagnose cancer.

About four of every five cases that are first diagnosed as cancer of unknown primary eventually are diagnosed as specific types of cancer. CUP most often is found in the lymph nodes, liver, lung, peritoneum (lining of the bowel) or bone. Cancer of unknown primary often is challenging because:

  • It tends to be aggressive
  • The exact origin of cancer is unknown, so it may be more challenging to choose the best treatment
  • It often has spread to many sites in the body before it is found

Cancer of Unknown Primary Types

Although doctors are unable to determine where CUP began, they study the cancer to find out as much as possible about it. After looking at the cancer cells under a microscope, they usually decide the cancer belongs in one of the following categories:

Adenocarcinomas: About six of every 10 cancer of unknown primary cases are adenocarcinomas, meaning they began in gland cells. Most frequently, the primary sites are the lung, pancreas, breast, prostate, stomach, liver or colon.

Poorly differentiated carcinoma: Cancer cells are present, but they do not have enough detail for doctors to decide the type of cancer. Around 10% of these CUP cases are found to be lymphoma, melanoma or sarcoma.

Squamous cell cancer: The cells are flat, similar to cells on the skin or linings of some organs.

Poorly differentiated malignant neoplasm: Cells are definitely cancer, but they are so abnormal it cannot be determined what type of cell or part of the body they began in. Sometimes they are lymphomas, sarcomas or melanomas.

Neuroendocrine carcinoma: This type of CUP begins in the neuroendocrine system, making the cells like nerve cells and hormone-making cells. They are scattered in organs including the esophagus, stomach, pancreas, intestines and lungs.

If you have been diagnosed with cancer of unknown primary, it is important to be evaluated by expert physicians. We can help. Call 1-877-632-6789 to make an appointment or request an appointment online.


© 2014 The University of Texas MD Anderson Cancer Center