Beat one cancer, risk up for another type
■ A new resource provides data showing that the chances for a subsequent malignancy among survivors vary by type of first cancer and age of diagnosis.
By Susan J. Landers — Posted Feb. 19, 2007
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Washington -- The good news about cancer survivors is that their numbers continue to grow. The bad news is that they have an increased risk of developing a second malignancy.
The National Cancer Institute analyzed data from 2 million survivors and placed this risk at 14% higher than would be expected in the general population.
Five-year cancer survival rates have been climbing steadily over the last few decades. Among adults, the rates have risen from about 50% 30 years ago to 66% in 2002, according to recent studies. The survival rates are even better for children, increasing from 61% to 79% during that same period.
In its new report, "New Malignancies Among Cancer Survivors: SEER Cancer Registries, 1973-2000," NCI researchers examined data gathered during those 27 years and determined the risks of subsequent malignancies for more than 50 adult and 18 childhood cancers. The publication is the first comprehensive analysis of the risk of developing a new malignancy, said Rochelle Curtis, a research statistician in the Radiation Epidemiology Branch of the NCI's Division of Cancer Epidemiology and Genetics. She spoke Jan. 24 at an NCI briefing.
The report is intended to be a resource for doctors and other health care professionals and policymakers. "The burden of subsequent cancers is not borne equally among all cancer survivors," Curtis said. Identifying those at elevated risk can help physicians and patients develop strategies for early detection and prevention, as well as encourage changes in high-risk behaviors, she said.
With 10.5 million such survivors in the United States, primary care physicians may have patients who successfully battled cancer years earlier and are now facing round two. For example, among long-term survivors of Hodgkin's lymphoma, solid tumors are the No. 1 cause of death, according to the new analysis.
Not only is there an increased risk of a second tumor distinct from the first and perhaps in a different part of the body, but aggressive treatment for an earlier malignancy also may have a deleterious impact on a patient's heart, lungs or brain. The rigorous course of treatment necessary to beat a first cancer also can lead to anxiety and depression -- all serious complications, said Lois B. Travis, MD, ScD, senior investigator in NCI's Division of Cancer Epidemiology and Genetics.
Healthy lifestyle remains vital
Although radiation and chemotherapy long have been recognized as probable causes of second cancers, it may be less recognized that tobacco, alcohol and poor diet continue to play significant roles in tumor development. Physicians should keep up the mantra for lifestyle changes because, perhaps surprisingly, the message is still not getting through -- even to the population that already has had one encounter with cancer, Curtis said.
The risk for a second tumor is about as high for women as it is for men, indicating a need for continuing education for both on the benefits of proper diet and good health habits.
In addition, Dr. Travis acknowledged roles played by environmental contaminants as well as age, gender and genetics in tumor development. She also spoke at the briefing.
For the new analysis, cancer institute researchers reviewed data from nine cancer registries in the institute's Surveillance, Epidemiology and End Results -- SEER -- Program. The registries include survivors in five states and four metropolitan areas. Among this group, about 185,000 developed second cancers.
The risk of second cancers for children who survived a first cancer was determined to be particularly high. In a study of 24,000 such survivors, 352 new malignancies were found where 58 would be expected in the general population. These survivors, now adults with the oldest in their early 40s, need to be followed particularly closely, researchers said.
The greatest risk of subsequent cancer occurred among children diagnosed with Ewing's sarcoma, Hodgkin's lymphoma, primitive neuroectodermal tumor of the central nervous system and retinoblastoma.
The researchers pointed out that the magnitude of risk for second cancers varies by type of first cancer as well as the age of diagnosis. For example, the overall risk of subsequent cancer was 18% higher among the 322,863 women diagnosed with a first cancer of the breast. The highest risk was associated with the diagnosis of cancer before age 40.
Many of the second cancers among this group also occurred in the breast, but there was an increased risk for cancer of the uterus and ovary. On the other hand, there was a lower risk for subsequent malignancies of the pancreas, cervix and lung, researchers said.
In another example, men who had survived a primary cancer of the testis were at higher risk for developing a new cancer than were men who survived prostate cancer, according to the report. But prostate cancer was associated with secondary cancers of the small intestine, soft tissue, bladder and thyroid.
Radiation treatment for testicular cancer appeared to be responsible for some solid tumors, and chemotherapy and radiotherapy seemed to be responsible for an elevated risk for acute non-lymphocytic leukemia.
The publication contains numerous charts and much detailed information and is available free from the National Cancer Institute.