People who have had cancer may in some cases have a higher than average risk of developing a new cancer — that is, a cancer not related to the spread, or metastasis, of the original tumor. While the vast majority of people diagnosed with cancer do not develop a different malignancy later in life, it’s important for survivors to be aware of factors that can put them at risk.
Pinning down the extent of that risk is difficult. For one, the rates of many cancers increase with age: the older a person gets, the more likely he or she is to develop certain forms of cancer, regardless of whether he or she has had cancer in the past.
People whose initial cancer was associated with certain environmental factors or lifestyle issues — such as exposure to harmful substances at work or at home, smoking, excessive sun exposure, poor diet, or drug abuse — may be at risk for future cancers of the same or different type. In many cases, such risks can be reduced by adopting healthier habits or reducing or eliminating exposure to substances that triggered the first cancer. Examples include quitting smoking and avoiding sunburn.
Like age, there are several factors beyond an individual’s control that can influence the risk of a second cancer. One of these is genetics. People who inherit genetic mutations or other abnormalities can be at risk for a variety of different types of cancer. Individuals with a mutation in the BRCA1 or BRCA2 genes, for example, have a heightened risk of cancers of the ovaries and fallopian tubes in women, breast, prostate (in men), and pancreas. Such individuals remain at elevated risk for these cancers even if they’ve undergone treatment for one of them.
In some cases, patients can take steps to reduce their chances of developing a second cancer. A woman with a BRCA gene mutation who develops breast cancer may have the option of having her breasts and ovaries surgically removed to lower her risk of future breast or ovarian cancer.
Radiation and chemotherapy
Some of the therapies used to treat cancer can also raise the risk of other malignancies. Radiation therapy and many types of chemotherapy work by damaging DNA in tumor cells, causing them to die. But such damage can occur in normal cells as well, potentially putting them on a path toward cancer.
As physicians have gained experience with different types of therapy, they’ve often been able to develop reduced-intensity regimens that effectively kill cancer cells but produce fewer long-term risks. This is particularly true in the field of childhood cancer.
For many survivors, especially those whose treatment or genetics may place them at higher risk of a second cancer, physicians may suggest more frequent screenings to detect any such cancers at the earliest, most treatable stages. Patients should talk with their physician about which strategy makes the most sense for them.