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    #1194: Thyroid cancer increase puzzles experts

    Link: http://oralcancernews.org/wp/2009/07/thyroid-cancer-increase-puzzles-experts

    Wed, Jul 15, 2009

    Oral Cancer News

    Source: HealthDay News
    Author: Staff

    Intensified screening doesn’t entirely explain the jump in thyroid cancers
    noted in the United States since 1980, and scientists now believe that other
    as-yet-unknown factors are to blame.

    A new study finds that thyroid tumors of all sizes are being picked up, not
    just the smaller ones that more aggressive screening would be expected to
    detect.

    “You cannot simply explain this by increased screening, there’s a real
    increased incidence,” said Dr. Amy Chen, lead author of a study published
    online July 13 in the journal Cancer.

    Although, “some of this increased incidence is due to increased screening
    finding smaller tumors,” she added.

    The findings surprised one expert.

    “I wrote a chapter about this for a textbook about a year ago and I came
    away thinking this [rise in cancers] is a reflection of enhanced
    diagnostics,” said Dr. Bruce J. Davidson, professor and chairman of
    otolaryngology-head and neck surgery at Georgetown University Hospital in
    Washington, D.C. But, “it is more disturbing that it’s not just small
    tumors; it seems to be all tumors,” he said.

    An estimated 37,200 new cases of thyroid cancer will be diagnosed this year,
    according to the U.S. National Cancer Institute. Fortunately, the cancer is
    considered highly curable, but the researchers said survival rates have not
    improved with better detection.

    Until now, an increase in cases seen over the past three decades was
    attributed to increased use of ultrasound and image-guided biopsy to detect
    tumors. Some researchers had found that thyroid cancer was diagnosed more
    often in areas with higher incomes and less in uninsured populations, adding
    further credence to this theory.

    Looking at thyroid cancer cases from 1988 to 2005 reported in a large cancer
    database, Chen and her team found a higher incidence not just in small
    tumors, but across all sizes.

    The most pronounced increase was seen in primary tumors under 1.0
    centimeters ‹ small ones for which many experts consider it safe to take a
    wait-and-see approach. The rate for these tumors rose almost 10 percent per
    year in men (1997 to 2005) and 8.6 percent per year in women (1988 to 2005).

    But the authors also saw a 3.7 percent annual increase in tumors exceeding 4
    centimeters in men and a 5.7 percent yearly rise in these tumors in women.

    Cancers that had spread also increased in men by 3.7 percent annually and in
    women by 2.3 percent.

    Thyroid cancer can be caused by exposure to radiation but there has been no
    evidence of increased exposure to radiation among Americans.

    “People have looked at background radiation and nothing really has come of
    that that’s very useful. And certainly not useful to us in why there would
    be a bump in incidence in the last 15 years,” Davidson said.

    Chen proposed in the study that environmental, dietary and genetic issues be
    explored.

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