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Re: radiology technology as a profession
Kevin Donohoe, MD, wrote:
>
> Anyone in Radsafe land have at hand literature that would address the
> question below? It would be particularly helpful if it were
> understandable by a lay person.
>
> Please remember to send your reply directly to me at:
>
> kjd@nucmed.bidmc.harvard.edu
>
> Thanks for your help.
Hi Kevin, nice to 'see' you again. :-)
While I don't have a specific rad tech/leukemia ref at hand (I thought I
had seen one), note that BEIR V states (p247) in the Section on
Leukemia, following reports of studies of the Japanese survivors and
medical patients, eg, the ankylosing spondylitis patients, and 30,000
women treated for cervical cancer, and women treated for other cancers,
that: "Early cohorts of radiologists in the US (Lewis 1963, Science;
Matanoski et al 1984, p.83 in "Rad carcinogenisis: Epi and Biological
Significance" Boice, Fraumeni eds., Raven), the UK (Court & Doll 1958,
Br Med J.), and China (Wang et al 1988, J. Nat Cancer Res.), who were
exposed to x-rays occupationally in the days preceding modern safety
standards, also have shown an increased incidence of ALL and CGL."
Unlike other studies, BEIR here does not go further in producing a
linear value of the excess, so it is not likely significant. They would
surely have reported any other practitioner data reported (prior to
ca. 1989) that would have indicated a positive result. While not
specific
to leukemia, I attach below a recent paper abstract by Boice based on a
health survey of the >100,000 female rad techs certified since 1926 to
assess breast cancer. (Perhaps there is a resource there that can point
to other work from this cohort on leukemia.) I note below also some
other
leukemia studies in medical patients subject to long-term x-ray exposure
that may be relevant for perspective on lifetime exposure effects.
Note that Roz Yalow refers to the 1981 paper by Peter Smith and Sir
Richard
Doll about the *lack of effects* in UK radiologists who started practice
after
1921, vs the earlier (Court & Doll) study - which must have "excaped"
the
"vigilant review of all the data" by the BEIR Committee (yet another
one; in
the public interest of course) :-)
Regards, Jim Muckerheide
jmuckerheide@delphi.com
> > > My child is a high school sr. who is interested in becoming a radiology
> > > technologist. Recently a nurse told us that she would not recomend this
> > > because she new two radiology techs at the same hospital that had developed
> > > leukemia. She also knew of a third at another hospital. I have never heard of
> > > this before. Do you have any statistics or studies relative to this or could
> > > you helppoint me to a source of such information?
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Medical practioners
>From the abstract of Boice et al, 1995, in the Journal of the American
Medical Association, reporting on a case-control study to evaluate the
risk of breast cancer among women occupationally exposed to ionizing
radiation as radiologic technologists:
"A health survey of 105,385 women radiologic technologists
certified by the American Registry of Radiologic Technologists since
1926. Among 79,016 respondents, 600 breast cancer cases were
identified. Each of 528 eligible subjects with breast cancer was matched
to five control subjects based on age, year of certification, and
follow-up
time."
"Study subjects had been certified for a mean of 29 years; 63.8%
of
cases and 62.6% of controls worked as radiologic technologists for 10
years or more. Significant increased risks for breast cancer were
associated with early age at menarche (for <11 years of age: RR=1.79;
95%
confidence interval [CI], 1.09 to 2.94), nulliparity (RR=1.36; 95% CI,
1.04
to 1.78), first-degree relative with history of breast cancer (RR=2.07;
95% CI, 1.56 to 2.74), prior breast biopsy (RR=1.53; 95% CI, 1.17 to
2.00),
alcohol consumption (for >14 alcoholic drinks per week: RR=2.12; 95% CI,
1.06 to 4.27), thyroid cancer (RR=5.36; 95% CI, 1.64 to 17.5),
hyperthyroidism (RR=1.66; 95% CI, 1.02 to 2.71), and residence in
the northeastern United States (RR=1.66; 95% CI, 1.19 to 2.30). Jobs
involving radiotherapy, radioisotopes, or fluoroscopic equipment,
however,
were not linked to breast cancer risk, nor were personal exposures to
fluoroscopy or multifilm procedures. Use of birth control
pills, postmenopausal estrogens, or permanent hair dyes also were not
risk factors. Based on dosimetry records for 35% of study subjects,
cumulative exposures appeared low. Among women who worked more than
20 years, the RR for breast cancer was 1.13 (95% CI, 0.79 to
1.64).
"More than 50% of the reported breast cancers could be explained
by
established risk factors. Employment as a radiologic technologist,
however, was not found to increase the risk of breast cancer."
Boice, John D. , Jr, ScD; Jack S. Mandel, PhD; Michele Morin Doody, MS,
1995, "Breast Cancer Among Radiologic Technologists", JAMA 274:394-
401
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Practitioners
[ No excess cancers were found in British radiologists, with estimated
100-500 cGy lifetime doses. ]
Nobel Laureate Dr. Rosalyn Yalow states (1994) that:
"British radiologists before 1921 (including much extreme WWI
exposures) had 75% excess cancer-related deaths compared to other
physicians. However, those starting after 1921 (with general improved
radiation protection practices) had no excess cancer deaths, with
typical
excess exposures estimated at 100 to 500 rem (Smith and Doll 1981)"
Practitioners
[ No excess cancers were found in U.S. Army radiologic technicians, with
estimated 50-cGy doses. ]
Nobel Laureate Dr. Rosalyn Yalow states (1994) that:
"In WWII, 6500 radiologic technicians had an estimated 50 rem in
training, with 24 months median service. A 29-year follow-up found no
increased malignancies compared to army medical, laboratory, and
pharmacy technicians." (Jablon 1978)
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Patients: x-rays and leukemia
Dr. Yalow reports also (1988) that:
"A case control study by Linos et al (1980) of 138 cases of
leukemia,
which represent all known cases in Olmstead County, Minnesota between
1955 and 1974 and matched controls, revealed that there was no
statistically significant increase in the risk of developing leukemia
after
radiation doses up to 300 rads to the bone marrow when these doses were
administered in small doses over long periods of time, as in the case of
routine medical care."
"Virtually all medical care is provided by the Mayo Clinic and
one
other private medical group practice and the record keeping and
estimations of bone marrow dose is very reliable."
---------------------------------------------------------------------
Patients: x-rays and leukemia
>From the Abstract, Boice et al report, 1991, in the Journal of the American
Medical Association:
"Exposure to diagnostic x-rays and the risk of leukemia, non-Hodgkin's
lymphoma (NHL), and multiple myeloma were studied within two prepaid
health plans. Adult patients with leukemia (n = 565), NHL (n = 318), and
multiple myeloma (n = 208) were matched to controls (n = 1390), and over
25,000 x-ray procedures were abstracted from medical records. Dose
response was evaluated by assigning each x-ray procedure a score based
on estimated bone marrow dose. X-ray exposure was not associated with
chronic lymphocytic leukemia, one of the few malignant conditions never
linked to radiation (relative risk [RR], 0.66). For all other forms of
leukemia combined (n = 358), there was a slight elevation in risk (RR,
1.17) but no evidence of a dose-response relationship when x-ray
procedures near the time of diagnosis were excluded. Similarly, patients
with NHL were exposed to diagnostic x-ray procedures more often than
controls (RR, 1.32), but the RR fell to 0.99 when the exposure to
diagnostic x-ray procedures within 2 years of diagnosis was ignored. For
multiple myeloma, overall risk was not significantly high (RR, 1.14),
but
there was consistent evidence of increasing risk with increasing numbers
of diagnostic x-ray procedures. These data suggest that persons with
leukemia and NHL undergo x-ray procedures frequently just prior to
diagnosis for conditions related to the development or natural history
of
their disease. There was little evidence that diagnostic x-ray
procedures
were causally associated with leukemia or NHL. The risk for multiple
myeloma, however, was increased among those patients who were
frequently exposed to x-rays."
Boice JD Jr, Morin MM, Glass AG, Friedman GD, Stovall M, Hoover RN, and
Fraumeni JF Jr, "Diagnostic x-ray procedures and risk of leukemia,
lymphoma, and multiple myeloma", Epidemiology and Biostatistics Program,
National Cancer Institute, Bethesda, MD 20852. JAMA 265: 1290-1294
(1991)
----------------------------------------------------------------------
Professor and Chairman emeritus of the Dept of Biochemistry, U.
Missouri-Columbia School of Medicine, Dr. Don Luckey reports (1991)
that:
"Sanders and Kathren noted that only one bone sarcoma originated at
skeletal doses of <10 Gy in the 2000 German patients who were injected
with Radium for tuberculosis or ankylosing spondylitis between 1944 and
1951.(Sanders 1983) And they note that radiotherapy with more than 10 Gy
is only occasionally correlated with increased bone tumors in adults."
"Although nonlymphatic leukemias are readily induced by excess ionizing
radiation, low doses do not evoke this rare disease.(Gunz 1964; Linos
1980) Linos et al. suggested a negative association between medical
radiation doses and leukemia. Study of two carefully selected controls
for each of 138 leukemia cases allowed Linos et al. to state: 'No
statistically significant increase was found in the risk of developing
leukemia after radiation doses of 0 to 300 rads (3 Gy) to the bone
marrow when these amounts were administered in small doses over long
periods of time, as in routine medical care.' Their examination of
patients with doses of 1 to 50 cGy allowed them to state that the risk
of either acute or chronic lymphocytic or myelocytic leukemia is
lessened by low doses of radiation.(Linos 1980)"
"The concepts of Bross and associates (1979) regarding the dangers from
diagnostic X-rays to patients were not supported by statistically
significant data and were severely criticized by Boice and Land. The
latter group had previously found no excess leukemia in 100 cases of
fluoroscopic chest examinations. (Boice 1979) No excess leukemia was
found in women exposed to 5 to 10 Gy for cancer of the cervix. (Webster
1983) Although 42 to 85 new leukemias were predicted for this cohort
(BEIR III), only nine were found. Although it is readily induced by
high doses of ionizing radiation, low doses do not cause leukemia. (Gunz
1964; Leuenberger 1971) Using carefully selected controls, Linos et al.
indicated that the incidence of acute and lymphocytic leukemia is
lowered by therapeutic use of 1 to 50 cGy radiation in routine medical
care. (Linos 1980) This suggests hormesis with medical exposures.
Sakamoto et al. suggested that exposure of the spleen to about 10 cGy
twice weekly was the key to current methods of tumor therapy. (Sakamoto
1987)"
[Note that Sakamoto is recently retired and reporting on the success of
low-dose immune system stimulation for cancer and non-Hodgkins lymphoma
therapy (90% 5-year survival following traditional rad therapy - 36%
survival). He was using 10 cGy fractions to about 150 cGy over 3 weeks.
His presentations included last years ACNP/SNM meeting in Denver if you
were there. There is some interest at Johns Hopkins and UCSF that I know
of. He was also with us in Washington DC, and at the BELLE Conference in
Research Triangle Park in Nov 96.]