Surgery for cancer of unknown primary

Surgery is sometimes 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, or metastasized, when it is diagnosed.

Surgery may be done for different reasons. 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 only have CUP in 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. 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 only found in lymph nodes in the neck. Radiation therapy and chemotherapy are usually given after this surgery.

Find out more about neck dissection.

Inguinal lymph node dissection

The lymph nodes in the groin are called inguinal lymph nodes. Inguinal lymph node dissection (also called inguinal lymphadenectomy or groin dissection) is surgery to remove the lymph nodes from the groin. It may be offered if CUP is in these lymph nodes.

Find out more about 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 to women with adenocarcinoma of unknown primary that may have started in the breast and spread to these lymph nodes.

Find out more about axillary lymph node dissection.


A mastectomy is surgery to remove the entire breast. It may be offered to women who have adenocarcinoma of unknown primary that may have started in the breast. Because doctors 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 mastectomy.

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.

Surgical debulking

Surgical debulking removes as much cancer as possible before chemotherapy is given. It is most often used to treat women who have CUP in the lining of the abdomen (called the peritoneum) and doctors think that the ovary is the primary site.

Side effects

Side effects can happen with any type of treatment for CUP, but everyone’s experience is different. Some people have many side effects. Other people have few side effects or none at all.

Side effects can develop any time during, immediately after or a few days or weeks after surgery. Sometimes late side effects develop months or years after surgery. Most side effects will go away on their own or can be treated, but some may last a long time or become permanent.

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.

Questions to ask 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

  • Fizazi K, Greco FA, Pavlidis N, et al . Cancers of unknown primary site: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up. Annals of Oncology. Oxford University Press; 2011.
  • Greco FA & Hainsworth JD . Cancer of unknown primary site. DeVita VT Jr, Lawrence TS, & Rosenberg SA. Cancer: Principles & Practice of Oncology. 10th ed. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins; 2015: 113:1720-1737.
  • Kim KW, Krajewski, KM, Jagannathan JP, et al . Cancer of unknown primary sites: what radiologists need to know and what oncologists want to know. AJR: American Journal of Roentgenology. The American Roentgen Ray Society; 2013.
  • National Comprehensive Cancer Network. Occult Primary (Cancer of Unknown Primary [CUP]) (Version 3.2014).