Cancer Research Highlights
Study Finds No Overall Increased Brain Tumor Risk from Cell Phones
A large international study has found no overall increased risk of two types of brain tumors among people who use mobile phones. The case-control Interphone study analyzed data on cell phone use from more than 5,000 patients in 13 countries who had either glioma or meningioma and from matched comparison groups.
No evidence of overall increased risk was found when the results were analyzed according to increasing numbers of calls, duration of call time, or time since a person started to use cell phones. For a very small proportion of persons who were heavy users, the researchers found an increased risk for glioma, but the results were inconclusive.
“An increased risk of brain cancer is not established from the data from the Interphone study,” said Dr. Christopher Wild, director of the International Agency for Research on Cancer, which coordinated the study. He noted, however, that further research was warranted because of the result involving heavy users and because usage patterns continue to change, particularly among young people.
The findings, published online May 18 in the International Journal of Epidemiology, are consistent with the majority of published reports on cell phones and malignant or benign brain tumors. No previous study, however, has included as many patients with brain and central nervous system tumors who had histories of cell phone use, particularly long-term and heavy users of mobile phones, as this one.
“Interphone will be the most definitive study of cell phones and risk of brain and central nervous system tumors for some time to come,” said Dr. Martha S. Linet, chief of the Radiation Epidemiology Branch in NCI’s Division of Cancer Epidemiology and Genetics. She praised the investigators for going to great lengths to understand and address the methodological challenges in studying cell phone usage in patients with cancer.
The study focused on patients who developed brain tumors between age 30 and 59. A Nordic study is expected to provide some results on children in the next few years, Dr. Linet said. Plans are also under way for a study called MOBI-KIDS, which would evaluate risk from new communications technologies, including cell phones, and other environmental factors in people between age 10 and 24.
Cell phones emit a form of radiation known as radiofrequency energy, but how this affects cancer risk is not clear. Dr. Linet noted that although cell phone usage has been increasing, exposure to radiofrequency energy from cell phones to individuals has declined steadily. This is in part because technology has improved and because there are more cell phone towers, which reduces the amount of radiofrequency energy exposure to the user. The farther a cellular telephone is from the base station antenna, the higher the power level needed to maintain the connection.
Dr. Linet and her colleagues have been monitoring the incidence of brain cancer in the United States during the rise in cell phone usage. “We have not seen an increase in brain tumor incidence that one might expect if there were an increased risk of cancer from cell phone usage,” she said. “This is an important public health message.” (For more information, see NCI’s Cellular Telephone Use and Cancer Risk Fact Sheet.)
Cost of Cancer Care in the U.S. Doubled in the Past 20 Years
The total yearly medical cost of cancer in the United States nearly doubled from $24.7 billion in 1987 to $48.1 billion between 2001 and 2005, according to Dr. Florence Tangka of the CDC and her colleagues in an analysis published online May 10 in Cancer. This increase paralleled the overall increase in medical spending over the past 20 years and remained approximately 5 percent of total medical expenditures over the time period measured.
The researchers used data from 28,639 patients who took part in the National Medical Expenditure Survey in 1987 and data from 135,714 patients who took part in the Medical Expenditure Panel Survey between 2001 and 2005 to produce their cost estimates. All costs were adjusted to 2007 U.S. dollars.
The share of the total costs paid increased for private insurers (from 42 percent to 50 percent), Medicare (from 33 percent to 34 percent), and Medicaid (from 1 percent to 3 percent) but decreased for other public programs (from 7 percent to 5 percent). Out-of-pocket costs decreased from 17 percent to 8 percent.
The delivery of cancer treatment shifted away from the inpatient setting and toward the outpatient setting during the same time period, with 64.4 percent of cancer costs generated by inpatient treatment in 1987 but just 27.5 percent of costs generated by inpatient treatment during 2001 through 2005. Along with increased outpatient costs, spending on cancer-related prescription drugs as a proportion of all cancer-related costs also rose, from 1.8 percent to 6.1 percent.
For private insurance and Medicaid, over 80 percent of the increase in costs could be explained by the increased prevalence of cancer from 1987 to 2005. For Medicare and other public insurance, the cost per person actually decreased; however, the increase in prevalence seen with an aging population “more than made up for a decrease in costs per person,” explained the authors.
Liver Cancer Cases in the U.S. Continued to Rise Through 2006
Rates of the most common form of liver cancer, hepatocellular carcinoma (HCC), continued to rise in the United States, increasing an average of 3.5 percent each year from 2001–2006, according to an analysis published May 7 in the CDC’s Morbidity and Mortality Weekly Report. Close to one-fifth of all cancers worldwide are caused by infectious agents, including chronic infections with hepatitis B virus (HBV) and hepatitis C virus (HCV).
Using population data from 45 cancer registries (SEER and CDC’s National Program of Cancer Registries) that cover about 90 percent of the U.S. population, CDC researchers identified 48,596 HCC cases during that period and found that incidence rose from 2.7 to 3.2 cases per 100,000.
Racial and ethnic disparities in HCC have been persistent. While Asians/Pacific Islanders had the highest incidence rate (7.8 per 100,000) among subpopulations; that rate did not increase during the study period. Hispanics had the next highest rate (5.7), which increased by only 1.7 percent per year; by contrast, the incidence rate among all non-Hispanics was much lower (2.8) but increased twice as fast, at 3.6 percent per year. African Americans had a slightly lower rate than Hispanics (4.2), but their rate increased the fastest, at 4.8 percent per year. Whites had the next fastest increase, 3.5 percent per year, but the lowest incidence rate (2.6).
“The age and race profile of persons with HCC reflects the demographic characteristics of persons with chronic viral hepatitis,” wrote the authors of an accompanying editorial note. “Development of viral hepatitis services, including screening with care referral for persons chronically infected with HBV or HCV, full implementation of vaccine-based strategies to eliminate hepatitis B, and improved health surveillance are needed to reverse the trend in HCC.”
Doctors Urged to Monitor Hypertension in Cancer Patients Treated with Anti-VEGF Therapies
Patients with cancer who will be treated with certain anti-angiogenesis agents should have their blood pressure monitored carefully and managed prior to and during treatment, according to recommendations published in the May 5 Journal of the National Cancer Institute. The recommendations were developed by an expert panel convened by the Investigational Drug Steering Committee in NCI’s Division of Cancer Treatment and Diagnosis.
The report covers the use of agents that target the vascular endothelial growth factor (VEGF) signaling pathway, a key regulator of blood vessel development to tumors. FDA-approved agents in this drug class include bevacizumab (Avastin), pazopanib (Votrient), sunitinib (Sutent), and sorafenib (Nexavar). All of these VEGF signaling pathway inhibitors have been associated with cardiovascular side effects, particularly hypertension, explained panel chair Dr. Michael Maitland of the University of Chicago, and his colleagues. As a result, they wrote, “Oncologists and cardiovascular medicine specialists have increasingly recognized that the prevention and management of these toxic effects is important for these potentially life-sustaining anticancer agents to benefit the greatest possible number of patients.”
The recommendations were developed based on the available published data on hypertension in patients treated with these agents, as well as the panel’s experience with the use and development of these drugs and current standards for managing hypertension. Based on its review, the panel advised that patients who will receive VEGF signaling pathway inhibitors undergo a formal risk assessment for cardiovascular complications from treatment; that efforts to control hypertension should begin prior to starting treatment with any of these therapies; and that active monitoring and management of hypertension continue after treatment has begun.
When necessary (e.g., because of hypertension-related symptoms or difficulty controlling blood pressure), the panel recommended that treatment with VEGF signaling pathway inhibitors can be temporarily discontinued or the dose reduced to bring hypertension under control. Nevertheless, they advised, efforts “should be made to maintain the patient at the highest tolerable dose” of these inhibitors.