The rate of "second cancers" have been on the upswing for the past few decades, increasingly affecting the health and lives of cancer survivors, according to a new report.

"Second cancers" refer to the development of new, unrelated cancers in the bodies of cancer survivors. For some, the risk is greater for developing certain other types of cancer, and the appearance of the new cancer isn't a recurrence or the spread of the initial tumor -- it's an independent manifestation of the disease.

Approximately 1-in-5 (19 percent) new cases of cancer in the U.S. involves an individual who already had the disease, according to a recent study. The rate was at nine percent during the 1970s and has since risen 300 percent. During the same time frame, the rate of first cancers rose just 70 percent.

The data tells two different stories: increasingly U.S. residents are surviving cancer and experiencing longer lives, but they are increasingly at risk of cancer as they age.

The same form of cancer can manifest in the same organ as the first time, but new forms of cancer can also appear in different organs, tissues or sites. One cause for second cancer can be field cancerization, which is when the whole organ and nearby organs or tissues may have been exposed to the cancer-causing agents that instigated the first case of cancer. Additionally, some cases of second cancers don't even have to be nearby to be linked to the cancer-causing agent that stimulated the first cancer case.

Gene mutations, risk factors (smoking, alcohol or HPV) and family cancer syndromes caused by abnormal gene changes can also lead to hereditary ovarian cancer, hereditary cancer and some other cancers, as well as cause incidents of second cancers. For example, smoking can incite numerous types of cancer, including bladder cancer, lung cancer and larynx cancer. Also, treatments used to relieve survivors of cancers, such as radiation, can heighten the likelihood of developing a second type of cancer later in life -- although that's increasingly less likely due to advances in treatment and medicines.

Nonetheless, there are added medical challenges for those with second cancers, and there are fewer treatment options. Radiation treatment and some drugs must be avoided to limit heart and nerve damage. After undergoing chemotherapy or radiation, enduring the same type of treatment would be too much for the body, particularly if patients have particular genetic risks.

Experts have issued advice for cancer survivors to reduce the risk of developing a second form of cancer. Survivors should design "a survivorship plan," which details a summary of symptoms, treatment and how it was monitored. Additionally, survivors should submit to screenings for numerous types of cancer as well as any suggested tests (colonoscopies, mammograms, HPV or Pap tests). Lastly, survivors should relax and use social media and professional resources for help and guidance.

Future research will explore how genetics and therapy interact, also the link between radiation therapy and other agents that cause cancer.