Treatments for undifferentiated carcinoma of unknown primary

Last medical review:

Undifferentiated carcinoma of unknown primary (undifferentiated CUP) means that the cells of these tumours look very different from normal cells. This makes it difficult for the healthcare team to tell where the cancer may have started or what type of CUP it is.

Chemotherapy is the main treatment for undifferentiated CUP. Your healthcare team will offer the type of chemotherapy that they think will work best. This is referred to as empiric chemotherapy. They will usually give 2 or more drugs. Most drug combinations include at least one of the following:

  • a platinum drug – either cisplatin or carboplatin
  • a taxane drug – either paclitaxel or docetaxel

Another drug that may also be offered for undifferentiated CUP is etoposide (Vepesid).

The most common drug combination used is carboplatin and paclitaxel.

Researchers are still looking for the most effective drug combinations for undifferentiated CUP.

Clinical trials

Talk to your doctor about clinical trials open to people with CUP in Canada. Clinical trials look at new ways to prevent, find and treat cancer. Find out more about clinical trials.

If you can’t have or don’t want cancer treatment

You may want to consider a type of care to make you feel better without treating the cancer itself. This may be because the cancer treatments don't work anymore, they're not likely to improve your condition or they may cause side effects that are hard to cope with. There may also be other reasons why you can't have or don't want cancer treatment.

Talk to your healthcare team. They can help you choose care and treatment for advanced cancer.

Expert review and references

  • Tien Le , MD, FRCSC, DABOG
  • American Society of Clinical Oncology (ASCO). Unknown Primary: Types of Treatment. 2021:
  • Fizazi K, Greco FA, Pavlidis N, Daugaard G, Oien K, Pentheroudakis G . Cancers of unknown primary site: ESMO clinical practice guidelines for diagnosis, treatment and follow-up . Annals of Oncology . 2015 : 26(Supplement 5):v133–v138 .
  • PDQ Adult Treatment Editorial Board. Carcinoma of Unknown Primary Treatment (PDQ®) – Health Professional Version. Bethesda, MD: National Cancer Institute; 2018:
  • PDQ Adult Treatment Editorial Board. Carcinoma of Unknown Primary Treatment (PDQ®) – Patient Version. Bethesda, MD: National Cancer Institute; 2021:
  • Yentz S, Bhave M, Cobain E, Baker L. Cancer of Unknown Primary. DeVita VT Jr., Lawrence TS, Rosenberg SA, eds. DeVita, Hellman, and Rosenberg's Cancer: Principles & Practice of Oncology. 11th ed. Philadelphia, PA: Wolters Kluwer; 2019: Kindle version, ch 108, .
  • Tan WW . Medscape Reference: Metastatic Cancer With Unknown Primary Site . 2022 :

Medical disclaimer

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