NEW YORK (Reuters Health) - People who live in volcanic areas may
have an elevated risk of developing thyroid cancer, a new study suggests.
Italian researchers found that between 2002 and 2004, rates of papillary
thyroid cancer -- the most common form of thyroid cancer -- were twice as
high in Sicily's volcanic region compared with the rest of the island.
Among people living in Sicily's Catania province, home to the active Mt.
Etna volcano, there were 32 cases of thyroid cancer per 100,000 women per
year, and six cases per 100,000 men. Across the rest of Sicily, those rates
were 14 and three per 100,000, respectively.
The large majority of cancers were papillary thyroid tumors, a slow- growing
form of the disease that accounts for most cases of thyroid cancer.
"The increase of thyroid cancer is striking in the volcanic area of Sicily
-- more than the double in respect to the rest of the island," senior
researcher Dr. Riccardo Vigneri, of the University of Catania Medical
School, told Reuters Health in an email.
Because all volcanoes are not the same, it's not clear whether people living
near any volcano might have an elevated risk of thyroid cancer, Vigneri
said.
Further research should be done to track rates of thyroid and other cancers
in these areas, according to Vigneri, who noted that about 500 million
people worldwide live in a volcanic region.
He and his colleagues report their findings in the current issue of the
Journal of the National Cancer Institute (NCI).
Located at the base of the neck, the thyroid gland produces hormones that
help regulate heart rate, blood pressure, body temperature and weight.
Thyroid cancer is relatively uncommon; in the U.S., for example, it is
diagnosed in about 37,000 people each year, according to the NCI.
But the incidence of the disease has been on the rise in recent decades, in
the U.S., France, Italy and elsewhere, Vigneri and his colleagues point out.
Risk factors include iodine deficiency and exposure to high levels of
radiation -- such as radiation treatment to the head and neck -- but beyond
that, little is known about the types of environmental exposures that might
contribute to the cancer.
According to Vigneri's team, it's possible that thyroid cancer rates were
higher in Catania because of chemicals that are present in drinking water
from the volcanic aquifer. "In many specimens of drinking water from the
volcanic area we found that four metals and the natural radioactive compound
radon 222 (were) increased over the maximum admissible concentration,"
Vigneri explained.
He added, however, that other explanations cannot be excluded.
More studies are needed to determine which, if any, drinking-water
contaminants might be involved in the excess thyroid cancer risk, according
to the researchers.
"If, as we suspect, the carcinogenic element is in drinking water," Vigneri
said, "either filtration or dilution with water from (a) nearby non-volcanic
environment is a potential way to lower the risk."
In most cases, the researcher noted, thyroid cancer is slow-growing and
frequently found early, when treatment is usually successful.
According to the American Cancer Society, 97 percent of people diagnosed
with the cancer are still alive five years later.
Initial symptoms of thyroid cancer can include a lump in the front of the
neck, voice changes or hoarseness, swollen glands in the neck and difficulty
breathing or swallowing -- though such symptoms more often have a cause
other than cancer.
Source : Reuters News Service
