|
 But the study did not test whether citrus fruits were the cause of
the skin cancers, and more work will be needed to confirm the
connection, the authors write in the Journal of Clinical Oncology.
The results, from a single “observational” study that may not
reflect the whole U.S. population, should be interpreted with
caution, said senior author Dr. Abrar Qureshi of the Warren Alpert
Medical School of Brown University and Rhode Island Hospital.
Qureshi worked on the study in collaboration with the Channing
Division of Network Medicine at Brigham and Women's Hospital in
Boston.
“Cutaneous malignant melanoma is a potentially life-threatening form
of skin cancer,” Qureshi said. “Although there have been recently
incredible advances in the treatment of melanoma, melanoma
prevention through the use of sun protection and skin cancer
screening is recommended.”
The researchers used data on more than 63,000 women in the Nurses’
Health Study and 41,000 men in the Health Professionals Follow-Up
Study, both of which ran from the mid-1980s to 2010. Every two to
four years, researchers collected data on participants’ dietary
patterns, and the men and women self-reported health events like
melanoma diagnosis, which were confirmed with medical records.
The participants answered questions about how frequently they
consumed grapefruit, oranges, grapefruit juice or orange juice, and
the total of these four categories was considered an estimate of
“overall citrus consumption,” although it does not include other
citruses like lemons and limes.
Over more than 20 years of follow-up, the researchers noted 1,840
cases of melanoma. Compared to people who ate citrus less than twice
a week, those who ate citrus two to four times per week had a 10
percent increased risk of melanoma.
Melanoma risk increased as citrus consumption increased, rising to a
36 percent increase in risk for people who ate the fruits more than
1.5 times per day, on average. Of the citrus fruits, grapefruit
seemed to have the strongest association with melanoma.
Even accounting for varying amounts of sun exposure and the
geographic location of the study participants, the association
between citrus fruits and skin cancer was still high, Qureshi said.
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Fresh citrus fruits contain furocoumarins, a family of photoactive
compounds that can make an individual more sun sensitive, and make
sun exposure more damaging to skin cells, Qureshi told Reuters
Health by email.
“We are NOT recommending changing fruit consumption as these fruits
and vegetables are important for overall health,” he said. “However,
until we learn more about these furocoumarins, those consuming fresh
citrus fruits on a regular basis should be extra careful with sun
exposure, and depending on their outdoor activities they should wear
appropriate sunscreen, hats and sun-protective clothing.”
In the U.S., there are about 30 cases of cutaneous malignant
melanoma for every 100,000 individuals, according to Marianne
Berwick of the University of New Mexico in Albuquerque, who wrote an
editorial accompanying the findings.
It is the fifth most common cancer in the U.S. and sixth worldwide,
Berwick told Reuters Health by email.
The authors of the new study were careful to account for as many
other explanations as possible, but still it is too soon to
generalize these findings to the average person, she said.
“This study must be replicated in order for it to be used for public
health messages,” Berwick said.
SOURCE: http://bit.ly/1ekfGZD Journal of Clinical Oncology, online
June 29, 2015.
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