Surgery for cancer of unknown primary

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Surgery is a medical procedure to examine, remove or repair tissue. Surgery, as a treatment for cancer, means removing the tumour or cancerous tissue from your body.

Surgery is often used to treat cancer of unknown primary (CUP). The type of surgery you have depends mainly on the size and location of the tumour. When planning surgery, your healthcare team will also consider other factors, such as your overall health. Surgery isn’t always possible because CUP has already spread to other areas of the body (metastasized) when it is diagnosed.

Surgery may be the only treatment you have or it may be used along with other cancer treatments. You may have surgery to:

  • completely remove a single tumour (this is an option if cancer is found in only one place)
  • remove as much of the tumour as possible (called debulking) before other treatments

The following types of surgery may be used to treat CUP. You may also have other treatments before or after surgery.

Lymph node dissection

A lymph node dissection removes lymph nodes that may have cancer in them. It may be offered if you have CUP only in the lymph nodes. The type of dissection done will depend on which lymph nodes have cancer in them.

Neck dissection

The lymph nodes in the neck are called cervical lymph nodes. A neck dissection (also called cervical lymph node dissection) is surgery to remove lymph nodes from the neck. It may be used to remove squamous cell CUP that is found only in lymph nodes in the neck. Radiation therapy and chemotherapy are sometimes given before or after this surgery.

Find out more about a neck dissection.

Inguinal lymph node dissection

The lymph nodes in the groin are called inguinal lymph nodes. An inguinal lymph node dissection is surgery to remove the lymph nodes from the groin. It may be offered if squamous cell CUP is in these lymph nodes.

Find out more about an inguinal lymph node dissection.

Axillary lymph node dissection

The lymph nodes in the armpit, or underarm, are called axillary lymph nodes. Axillary lymph node dissection (ALND) is surgery to remove the lymph nodes from the armpit. It may be offered for adenocarcinoma of unknown primary that may have started in the breast or the lung and spread to these lymph nodes.

Find out more about an axillary lymph node dissection.


A mastectomy is surgery to remove the entire breast. It may be offered for adenocarcinoma of unknown primary that may have started in the breast. Because the healthcare team can’t find the primary site in the breast, they remove the whole breast to try to make sure they remove all of the cancer.

A mastectomy is often done with an axillary lymph node dissection. Chemotherapy may be offered after a mastectomy for CUP.

Find out more about surgery for breast cancer, including a mastectomy.

Surgical debulking

Surgical debulking removes as much cancer as possible before chemotherapy is given. It is most often used to treat CUP in the lining of the abdomen (called the peritoneum) if the healthcare team thinks that the cancer may have started in the ovaries.

Find out more about surgery for ovarian cancer, including surgical debulking.

Surgical resection

A surgical resection removes part or all of an organ. It may be an option if there is only one tumour, it is the only place that cancer is found in the body and your healthcare team thinks they can completely remove it. Surgery is not offered for people who have CUP in different parts of the body.

For example, surgical resection may be offered if you have only one tumour in your liver, you are well enough to have surgery and you will have enough healthy liver tissue left after the tumour is removed.

Side effects of surgery

Side effects of surgery for CUP will depend mainly on the type of surgery, which parts of the body your doctors operate on and your overall health. Tell your healthcare team if you have side effects that you think might be from surgery. The sooner you tell them of any problems, the sooner they can suggest ways to help you deal with them.

Find out more about surgery

Find out more about surgery and side effects of surgery. To make the decisions that are right for you, ask your healthcare team questions about surgery.

Expert review and references

  • Tien Le , MD, FRCSC, DABOG
  • American Cancer Society . Treating a Cancer of Unknown Primary . 2018 :
  • 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:
  • National Comprehensive Cancer Network . NCCN Clinical Practice Guidelines in Oncology: Occult Primary (Cancer of Unknown Primary) Version 1.2023 . 2022 .
  • 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 :

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