Unknown Primary: Risk Factors

Approved by the Cancer.Net Editorial Board, 10/2022

ON THIS PAGE: You will find out more about the factors that increase the chance of developing cancer of unknown primary (CUP). Use the menu to see other pages.

A risk factor is anything that increases a person’s chance of developing cancer. Although risk factors often influence the development of cancer, most do not directly cause cancer. Some people with several risk factors never develop cancer, while others with no known risk factors do. Knowing your risk factors and talking about them with your doctor may help you make more informed lifestyle and health care choices.

Since CUP can be almost any type of primary cancer, the risk factors for all types of cancer are risk factors for CUP. The following factors may raise a person’s risk of developing CUP:

  • Age. The average age of people diagnosed with CUP is 60.

  • Tobacco use. This includes cigarette smoking, chewing tobacco, and cigar smoking.

  • Sun exposure. Getting too much sun may increase cancer risk. Protect your skin from the sun.

  • Exposure to large amounts of radiation.

  • Exposure to chemicals in some manufacturing industries.

  • Poor nutrition. Not following a healthy diet may raise the risk of developing cancer.

  • Lack of exercise. Not getting regular physical activity may increase the risk of developing cancer.

  • Family history. If your family has a history of cancer, then your risk of cancer increases. A family history means more than 1 brother, sister, parent, or grandparent has been diagnosed with a certain or related types of cancer, including breast, ovarian, or colorectal cancers.

The next section in this guide is Symptoms and Signs. It explains what changes or medical problems CUP can cause. Use the menu to choose a different section to read in this guide.