A large study that examined data over a 20-year period found that the incidence of brain tumors had increased by 200% in older adults. In people age 19 years and younger, brain tumors now are the second most common cause of cancer deaths after leukemia. But is brain cancer really on the rise — or simply more likely to be detected? A noted expert explains the latest research — and tells what he does to protect his own brain…
IS THE INCREASE REAL?
CT scans are an important tool for diagnosing brain tumors. Before they were introduced in the 1970s, many patients with tumors might have been misdiagnosed as having strokes or other neurological diseases. The increased use of CT scans — along with MRIs and brain biopsies — may have caused an apparent increase in brain tumors.
Using research that took into account better imaging technology, scientists at the National Brain Tumor Registry concluded that the incidence of new tumors has remained stable. The National Cancer Institute Brain Tumor Study actually found a slight decrease in the incidence of brain tumors between 1990 and 2002.
However, the data is murky. There does appear to be an increase in brain tumors in some populations, but it still is unclear if this is due to better diagnostic tests or other factors.
We know that secondary brain tumors (those that originate in other parts of the body before spreading to the brain) are about five times more common than primary tumors (ones that originate in the brain and tend to stay in the brain) — in part, because many people with cancer now are living long enough for the cancer to spread to the brain. About 30% of those who die from breast cancer are later found to have evidence of brain cancer. With lung cancer, about 60% will be found at autopsy to have had the cancer spread to the brain.
REDUCE THE RISK
Primary brain cancers are relatively rare, accounting for about 2% of all cancers. Each year, about 19,000 Americans are diagnosed with a primary brain cancer. Sadly, only about one-third of patients with brain or other nervous system cancers survive more than five years.
Brain tumors are difficult to treat. Surgery isn’t always possible or effective, because these tumors tend to grow rapidly and invade large areas of brain tissue. Unlike other blood vessels in the body, those in the brain are selective in what they allow to pass. This so-called blood-brain barrier makes it difficult to deliver chemotherapeutic drugs to brain tumors.
The causes of brain cancer are largely unknown, but there are some clear risk factors…
Dental X-rays. Most dentists routinely use X-rays during checkups. The danger: Radiation scatters and can potentially irradiate — and damage — brain cells. Even low-dose X-rays may increase the risk for gliomas (a type of brain tumor) and meningiomas (tumors that develop in the membranes that cover the brain and spinal cord).
I tell my dentist, flat-out, that I don’t want X-rays. An occasional X-ray probably isn’t harmful, but no one should get them routinely.
Air pollution. At Cedars-Sinai, we’re doing a study now to look at the association between air pollution and brain cancers. We see molecular changes in the brains of rats after three months of exposure to air pollution that are similar to the changes we see just prior to the development of brain cancer.
Electromagnetic radiation from cell phones, cellular antennas and the like. A Swedish study found that the risk for brain cancer is 250% higher in those who used a cell phone for up to an hour a day for 10 years.
This is controversial. Other, shorter-term studies have found no risk from cell-phone use. But we know that it typically takes 20 to 30 years before toxic exposures lead to cancer. Cell phones haven’t been around long enough to know what the long-term consequences might be.
My advice: Use a wireless earpiece when talking on a cell phone. If you don’t use an earpiece, hold the phone as far away from your head as possible. The amount of radiation that reaches the brain drops significantly with distance.
Caution: Children have thinner skulls than adults. It’s easier for electromagnetic radiation from cell phones to penetrate a child’s skull and reach the brain. It’s possible that even low levels of electromagnetic radiation can produce cancer-causing changes in brain cells. Children and young adults should always use an earpiece.
Hot dogs and other processed meats usually contain nitrites, substances that have been linked with brain tumors. I like a hot dog as much as anyone, but moderation is important. Also, whenever possible, buy nitrite-free hot dogs, bacon and other processed meats.
Heating plastic in the microwave. There isn’t direct evidence that using plastic containers in the microwave can increase brain tumors, but we know that the vinyl chloride in some plastics is a risk factor. Personally, I don’t use plastic containers or cover foods with plastic wrap in the microwave.
Pregnant women should be especially careful. We’ve found in animal studies that adult females exposed to vinyl chloride or other carcinogens might not develop brain tumors themselves, but their offspring face a much higher risk.