How do shared risk factors affect the risk of second cancers?

For some cancers, having that cancer means you are at an increased risk of getting another cancer in the same organ or nearby. This may be because the whole organ (and sometimes nearby organs and tissues) were exposed to the same cancer-causing agents that led to the first cancer. This means that the entire area could already have early changes that can lead to cancer. This is called field cancerization.

Field cancerization is one reason people might get a second cancer near the same area, such as a second colorectal cancer, breast cancer, lung cancer, bladder cancer, or head and neck cancer.

Shared environmental risk factors

For some cancers, the agent that caused the cancer isn’t always obvious. For example, although there are many risk factors for colorectal and breast cancer, many of these cancers have no clear cause.

For others, the cancers can be linked to things known to cause cancer, like smoking, alcohol, or HPV (human papilloma virus) infection. For example, cancer of the larynx (voice box) is often caused by smoking. But the larynx isn’t the only part of the body exposed to cigarette smoke, so it isn’t surprising that people who have had cancer of the larynx also have a higher risk of other smoking-related cancers, such as cancer of the mouth, throat, esophagus (tube connecting the throat to the stomach), and lung.

Sometimes the second cancer isn’t nearby, but is still linked to the same cancer-causing agent. For example, bladder cancer can be caused by smoking. People who have had bladder cancer have an increased risk of some other cancers linked to smoking, such as cancers of the lung and larynx.

Genes and family cancer syndromes

In some people, their cancer is linked to a family cancer syndrome. These syndromes are caused by abnormal gene changes (mutations) that are often inherited from a parent. Family cancer syndromes are often linked to increased risks of more than one kind of cancer. For example, women with hereditary breast and ovarian cancer syndrome, which is linked to mutations in the genes BRCA1 and BRCA2, have a high risk of breast, ovarian, and some other cancers. Hereditary non-polyposis colorectal cancer syndrome (HNPCC), also known as Lynch syndrome, is linked to a high risk of colorectal, endometrial, bladder, and some other cancers.

The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

Last Medical Review: December 11, 2014 Last Revised: December 11, 2014

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