ORLANDO Fewer than half of childhood cancer survivors who are deemed to be at high risk of secondary breast, colon, and skin malignancies follow cancer-screening and surveillance recommendations as adults, according to a new analysis of the large, longitudinal Childhood Cancer Survivors Study.
Skin cancer is the most common radiation-associated second malignancy in survivors, but just 26.7% of 4,833 survivors at high risk had ever had a complete skin exam, said Dr. Paul Nathan, an oncologist at the Hospital for Sick Children in Toronto.
High-risk survivors were the least compliant with colonoscopy recommendations: Only 11.5% of 794 survivors who were considered vulnerable for colorectal cancer had a colonoscopy during the 5 years before they were surveyed, Dr. Nathan reported at the annual meeting of the American Society of Clinical Oncology.
Women at high risk for breast cancer were more compliant with recommendations, he added; even so, only 46.3% of 521 in this group had a mammogram performed during the 2 years before they were asked about screening.
Most of the 8,318 survivors surveyed in this phase of the National Cancer Institute-funded study were in the care of family physicians. About 12.5% had been seen at a cancer center or within a long-term follow-up program in the previous 2 years. Another 12% reported no medical care during this time. The remaining patients were "predominantly seen by their primary care physician in their community," he said.
Cancer survivors and their primary care physicians need to be more vigilant, Dr. Nathan said. Individual primary care physicians may have only a few childhood cancer survivors in their practice, he said, but they should be made aware of these patients' special requirements.
"There is broad consensus that survivors of childhood cancer need regular surveillance and screening in the hope that if we pick up these cancers early, we can change the mortality [and morbidity]," Dr. Nathan said.
Study discussant Dr. Charles L. Bennett, professor of geriatrics, economics, and oncology at Northwestern University, Chicago, was unsure whether survivorship care was the responsibility of oncologists or primary care providers but suggested it is most likely a shared responsibility.
This study is important because "surveillance is essential, yet empirical data are lacking," Dr. Bennett said, adding that "these are real issues. These are lifelong concerns."
With a 5-year survival rate of 80% for pediatric cancers, most patients survive long term (J. Clin. Oncol. 2009;27:2308-18). Dr. Nathan estimated that about 9% of 325,000 survivors of childhood cancer who are alive in the United States will develop a new malignancy within 30 years of their original diagnosis. In addition, secondary malignancies are the leading cause of death among survivors who live at least 20 years beyond initial diagnosis.
The Childhood Cancer Survivors Study enrolled 20,602 people who were initially diagnosed with cancer in 1970-1986 and had survived at least 5 years. Of these original participants, 3,305 had been lost to follow-up and 1,541 had died by the time of the 2003 follow-up survey, on which the new study is based. Another 3,197 declined to participate in the survey and 990 were excluded from the analysis (among them, 960 survivors who had already developed a secondary malignancy). The average age of survivors interviewed was 31.2 years. A matched group of 2,661 siblings and 8,318 population controls was also assessed.
The study's primary aim was to determine adherence to the Children's Oncology Group's guidelines for following survivors of childhood cancers. Survivors were considered at high risk for the following:
▸ Skin cancer, if they were exposed to any radiation during childhood. An annual skin examination of treated areas is recommended. ("We know the rate of nonmelanoma skin cancers in irradiated areas is approaching 7% for survivors over 30 years," Dr. Nathan noted.)
▸ Breast cancer, if they received 20 Gy or more of radiation therapy to the breast during childhood. Mammography is recommended every 1-2 years beginning at age 25 years, or 8 years after the initial cancer diagnosis for these patients.
▸ Colorectal cancer, if they received 30 Gy or more of radiation to the abdomen, pelvis, or spine. Screening colonoscopy is recommended every 5 years starting at age 35 years.
In a secondary analysis, the researchers compared survivors who were not at high risk of secondary cancers with matched controls from the National Health Interview Survey of the general population to determine adherence to U.S. Preventive Services Task Force cancer screening guidelines for breast, colon, and cervical cancer.
They found that these survivors were more likely to undergo recommended mammography (67%, vs. 58% of controls), were more compliant with Pap smear recommendations (82% vs. 70%), and had a comparablealbeit lowrate of recommended colonoscopy (24% in both groups).