Because healthcare providers don’t know the why, how, or where of cancer of unknown primary origin (CUP), it’s hard to identify risk factors for it.
Experts do know, however, that smoking is a risk factor for many kinds of cancer that could lead to CUP.
Certain foods have been linked to cancers of the stomach, colon, or rectum. These are all possible sources of CUP.
Melanoma, a type of skin cancer, is another source of CUP.
Also, a certain family cancer history may be a risk factor. If more than 1 close relative, such as a grandparent, parent, or sibling, has been diagnosed with colorectal, ovarian, or breast cancer, you may have a higher risk of cancer. If you have a relative who has or had CUP, your risk for it is higher. Having a relative with CUP also increases your risk for lung, colon, and pancreatic cancers.
To lower your risk for cancer, including CUP: