While the number of cancer survivors has tripled since the 1970s and continues to grow decades later, the cost of that survival for many of them has been the development of secondary cancers and cardiovascular disease related to radiation treatment, according to an upcoming report by a scientific committee.
The committee, convened by the National Council on Radiation Protection and Measurements met over a period of five years to consider some of the most serious repercussions of radiation therapy and make recommendations to more comprehensively assess the risks related to treatment. They plan to issue a comprehensive report of their findings, and have also published commentary in this week's Journal of the National Cancer Institute.
"For many survivors, the cost of the cure of their cancer has been late, life-threatening effects of therapy," said Dr. Lois B. Travis, director of the Rubin Center for Cancer Survivorship at the James P. Wilmot Cancer Center at the University of Rochester Medical Center. "We recognized that secondary malignant neoplasms and cardiovascular disease are among the most serious adverse effects experienced by the growing number of survivors worldwide," she added.
The development of these serious problems, she explained, are due to a combination of radiation therapy chemotherapy and other factors, including age, the environment, lifestyle habits and genetics.
Younger patients are especially susceptible to the effects of radiation, and the three cancers that have been most strongly associated with radiation are breast cancer, thyroid cancer and bone marrow cancers, including leukemia. Cardiovascular disease related to radiation therapy is most often associated with treatment for breast cancer and Hodgkin lymphoma, since radiation is applied to the chest.
While the committee focused its attention on radiation therapy, chemotherapy also carries the potential for life-threatening effects.
"With certain types of chemotherapy, there's an increased risk for developing leukemias," said Dr. Otis Brawley, medical director of the American Cancer Society.
Cole Whiting, just 10 years old, is now living with leukemia after beating another cancer, rhabdomyosarcoma of the sinuses, a few years back.
Shortly after completing 15 months of radiation treatment and chemotherapy for rhabdomyosarcoma, his family got word he developed yet another cancer -- acute myeloid leukemia.
"He was two weeks shy of finishing kindergarten when he got diagnosed. It was a result of the treatment he got for the first cancer," said his mother, Madonna Whiting. "It was even worse the second time, because we knew what we were in for having gone through it already."
Cole also suffers from problems with his short-term memory, has to regularly get growth hormone shots and take thyroid medication. He also found out that the roots of his teeth were destroyed, so all of his teeth will eventually fall out.
Whiting said the doctors did mention the possible long-term risks of Cole's cancer treatment, but at the time, all she could think about was dealing with his illness one day at a time.
"We had to do the chemotherapy to save my son's life," she said. "I wasn't even thinking about what could happen later at the time. I just wanted him to get well."
About 70 percent of children with cancer survive, and about 20 percent of those kids, like Cole, will experience five or more treatment-associated problems, Brawley said.
Childhood radiation may also have other effects later on, including fertility problems, stunted growth and cognitive deficits.
Despite Risks, Radiation Can Offer Huge Benefits
Clinicians say the benefits of radiation treatment for many types of cancer far outweigh the potential risks of experiencing serious adverse effects years later, and say radiation is now a lot safer than it once was.
"There is more advanced technology nowadays, and we can see structures we want to avoid and can shape the dose to avoid certain areas," said Dr. Candace Correa, assistant member of the Radiation Oncology Program at Moffitt Cancer Center in Tampa. "Radiation is very important for cancer for many patients. It offers a very big treatment advantage."
"We try to use radiation as sparingly as possible, but unfortunately, it is frequently part of the cure in a lot of cancers and it's absolutely necessary," said Brawley.
Healthy Behavior Can Lower Risk of Secondary Cancer
Travis said that even though there are risks associated with radiation, there are certain changes patients can make to reduce their risk of secondary cancers.
"For example, patients can stop smoking. Smoking has been shown to multiply the risk of treatment-associated lung cancer after Hodgkin lymphoma," she said. "We need to reinforce basic health messages, such as advising patients to stop smoking or make dietary modifications."
Health promotion, she continued, should be a vital component of cancer treatment plans.
"There is increasing recognition that the time of cancer diagnosis is a teachable moment. The patient is interested in his or her health, and it's the point at which we can intervene in regard to their habits to ensure that health promotion is a part of their survivorship plan."
The committee also recommends that there be long-term follow-up of cancer patients to evaluate risks of developing secondary cancers and other treatment-related effects.
"The relationship between radiation and late adverse effects has been looked at extensively in certain populations, but there hasn't yet been a systematic approach to assessing risk," Correa said. "Many cancers don't show up until years later, so we have to wait and continue to follow survivors."
"It's not enough just to cure a cancer patient," Travis added. " We have to think downstream and ask what is the potential cost of the cure to the patient in the future."