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mammography screening
Monty Charles wrote on August 13, 2000:
< I have a request for information regarding the justification for
mammography screening. I am looking for a scientific explanation
of national policy on the age range of women for which screening is
considered beneficial. The benefits of early detection of breast
cancer have to be balanced against the possible risk of induced
cancers in the general population of women being screened. The
balance presumably requires an estimate of the radiation risk, the
age dependence of this risk, and the effectiveness of the screening
process.
I would like to know if there is any published rationale for national
screening policies?
Many thanks
Monty Charles
Dr Monty Charles, Reader in Radiation Physics >
Here is my response:
"Breast cancer (BC) is the most common type of cancer among women in the
Western world. It is estimated that there will be more than 193,000 new BC
cases and more than 40,000 deaths due to this disease in 2001 in the U.S.
alone [1].
Numerous multi-national studies [2],[3],[4],[5] have consistently
demonstrated that BC mortality can be reduced by the use of mammography. In
the United States, routine mammographic screening, capable of early
detection of BC, has been identified as an important factor in recent
decreases in breast cancer mortality [6],[7].
The average glandular radiation dose due to mammograhic screening is in the
order of
3 mGy (300 mrad). While current knowledge of radiation effects in humans
does not permit
us to state with absolute certainty that there are no risks of low-level
radiation
exposure in any person, there are good epidemiological studies that suggest
beneficial health effects of such exposures [8], [9].
There is no evidence that the level of radiation dose that results from
mammographic screening increases a risk of cancer induction. In my opinion,
the only risk that a woman
is facing is the risk that screening will miss detecting her BC. Like with
any other diagnostic procedures there are false negatives...
References:
1. Greenlee RT, Hill-Harmon MB, Murray T, Thun M. Cancer Statistics, 2001.
CA A Cancer Journal for Clinicians. 2001; 51 (1): 15-36.
2. Ries LAG; Wingo PA; Miller DS; et al. The Annual Report to the Nation on
the Status of cancer, 1973 - 1997, with a Special Section on Colorectal
Cancer. Cancer. 2000; 88 (10): 2398-2424.
2. Smart CR, Hendrick RE, Ruthledge JH; Smith RA. Benefit of Mammography
Screening in Women Ages 40 to 49 Years: Current Evidence from Randomized
Controlled Trials. Cancer. 1995; 75 (7): 1619-1626.
3. Bjurstam N; Bjorneld L; Duffy S et al. The Gothenburg Breast Cancer
Screening Trial. Cancer. 1997; 80 (11): 2091-2099.
4. Feig S. Increased Benefit from Shorter Screening Mammography Intervals
for Women Ages 40 - 49 Years. Cancer. 1997; 80 (11): 2035-2039.
5. Smith RA. Breast Cancer Screening Among Women Younger Than 50: A Current
Assessment of the Issues. A CA Cancer J for Clinicians. 2000; 50 (5):
312-336.
6. American Cancer Society (ACS) website: http://www.cancer.org/
7. Ries LAG; Wingo PA; Miller DS; et al. The Annual Report to the Nation on
the Status of cancer, 1973 - 1997, with a Special Section on Colorectal
Cancer. Cancer. 2000; 88 (10): 2398-2424.
[8]Smith PG, Doll R. Mortality from all causes among British Radiologists
Br. J Radiol 1981; 54: pp 187-194 (1981)
[9]Matanoski G: Health effects of low-level radiation in shipyard workers
final report. 471 pages Baltimore, MD, DOE DE-AC02-79 EV10095, (1991). Also:
Matanoski, G Nuclear shipyard worker study (abstract) Radiat. Res. 133,
126-12."
Jodi Strzelczyk
Asst. Professor, Radiological Sciences
University of Colorado Health Sciences Center
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