Page 418 - 2014 Printable Abstract Book
P. 418
(PS7-68) Basal cell carcinoma incidence following low-dose occupational radiation exposures in US
Radiologic Technologists. Terrence Lee, MPH, NCI - Radiation Epidemiology Branch, Rockville, MD
Background: High doses of ionizing radiation (IR) are a known risk factor for basal cell
carcinoma (BCC), based on evidence from the Japanese atomic-bomb survivors, medically-exposed groups
and occupational data. Information on protracted low levels of IR exposures (<500 mGy) and BCC risk is
more sparse. Objective: To determine risk for incident BCC from cumulative low level exposure to IR in
US radiologic technologists with adjustment for potential confounders (e.g., sun exposure, host factors).
Methods: We studied 65,719 technologists who were cancer free at baseline and answered at least two
follow-up questionnaires between 1982 and 2008. A prospective cohort study design was used employing
the Cox proportional hazards model and Poisson regression. Analysis assessed risk associated with
radiation exposure in specific periods of age, time since exposure and calendar year. Results: The
cumulative mean dose (to the skin of the head, neck and arms) was 55.8 mGy (range: 0-1,735). There was
no evidence of an association between cumulative IR dose and BCC;the multivariate adjusted excess
relative risk per Gy (ERR/Gy) was -0.01 (95% CI -0.43, 0.52), although depending on the age adjustment
used some models yielded significant increasing trends with dose. Exposure under 30 years of age was
associated with a statistically significant increased BCC risk (ERR/Gy = 0.78; 95% CI 0.09, 1.61) adjusted by
gender and age, with lower risk at older ages (p=0.006); multivariate adjustment (including host factor
and sun exposure) did not materially affect the results. Exposure in earlier decades (before 1960) was
strongly associated (p<0.001) with a dose-related increased risk, although cautious interpretation is
warranted considering the unreasonably high estimates. There was no significant modifying effect of time
since exposure. Conclusions: There was evidence that low dose (largely under 500 mGy) occupational IR
exposure at younger ages was associated with excess risk for BCC, with lower risk for exposures at older
ages. The magnitude of BCC risk and the patterns of variation with exposure age are consistent with other
datasets. Because of large uncertainties in dosimetry and sensitivity to model specification, these findings
should be interpreted with caution.
(PS7-69) The evaluation of cerebrovascular accidents in long-term childhood cancer survivors treated
1
with cranial and supradiaphragmatic radiation therapy. Irma W.E.M. van Dijk, PhD ; Helena J.H. van der
1
2
2
3
Pal, MD, PhD ; Rob M. van Os, M.Sc. ; Yvo B.W.E.m. Roos, MD, PhD ; Elske Sieswerda, MD, PhD ; Elvira C.
3
3
1
3
van Dalen, MD, PhD ; Cecile M. Ronckers, PhD ; Foppe Oldenburger, MD ; Huib N. Caron, MD, PhD ; Caro
1
3
C.E. Koning, MD, PhD ; and Leontien C.M. Kremer, MD, PhD, Department of Radiation Oncology,
1
Academic Medical Center (AMC), Amsterdam, Netherlands ; Department of Medical Oncology, AMC,
2
Amsterdam, Netherlands ; and Department of Pediatric Oncology, Emma Children’s Hospital / AMC,
Amsterdam, Netherlands
3
Purpose: To evaluate the incidence and severity of symptomatic cerebrovascular accidents (CVAs)
in long-term childhood cancer survivors treated with cranial and supradiaphragmatic radiation therapy
(CRT, SDRT) and to assess dose-effect relationships. Patients and Methods: The single-center study cohort
included 1362 five-year survivors treated for a wide range of childhood cancer types. Physical radiation
doses for CRT and SDRT were converted into the equivalent dose in 2-Gy fractions (EQD2). Multivariable
Cox regression analyses were used to assess dose-effect relationships adjusting for sex, age at diagnosis,
Radiologic Technologists. Terrence Lee, MPH, NCI - Radiation Epidemiology Branch, Rockville, MD
Background: High doses of ionizing radiation (IR) are a known risk factor for basal cell
carcinoma (BCC), based on evidence from the Japanese atomic-bomb survivors, medically-exposed groups
and occupational data. Information on protracted low levels of IR exposures (<500 mGy) and BCC risk is
more sparse. Objective: To determine risk for incident BCC from cumulative low level exposure to IR in
US radiologic technologists with adjustment for potential confounders (e.g., sun exposure, host factors).
Methods: We studied 65,719 technologists who were cancer free at baseline and answered at least two
follow-up questionnaires between 1982 and 2008. A prospective cohort study design was used employing
the Cox proportional hazards model and Poisson regression. Analysis assessed risk associated with
radiation exposure in specific periods of age, time since exposure and calendar year. Results: The
cumulative mean dose (to the skin of the head, neck and arms) was 55.8 mGy (range: 0-1,735). There was
no evidence of an association between cumulative IR dose and BCC;the multivariate adjusted excess
relative risk per Gy (ERR/Gy) was -0.01 (95% CI -0.43, 0.52), although depending on the age adjustment
used some models yielded significant increasing trends with dose. Exposure under 30 years of age was
associated with a statistically significant increased BCC risk (ERR/Gy = 0.78; 95% CI 0.09, 1.61) adjusted by
gender and age, with lower risk at older ages (p=0.006); multivariate adjustment (including host factor
and sun exposure) did not materially affect the results. Exposure in earlier decades (before 1960) was
strongly associated (p<0.001) with a dose-related increased risk, although cautious interpretation is
warranted considering the unreasonably high estimates. There was no significant modifying effect of time
since exposure. Conclusions: There was evidence that low dose (largely under 500 mGy) occupational IR
exposure at younger ages was associated with excess risk for BCC, with lower risk for exposures at older
ages. The magnitude of BCC risk and the patterns of variation with exposure age are consistent with other
datasets. Because of large uncertainties in dosimetry and sensitivity to model specification, these findings
should be interpreted with caution.
(PS7-69) The evaluation of cerebrovascular accidents in long-term childhood cancer survivors treated
1
with cranial and supradiaphragmatic radiation therapy. Irma W.E.M. van Dijk, PhD ; Helena J.H. van der
1
2
2
3
Pal, MD, PhD ; Rob M. van Os, M.Sc. ; Yvo B.W.E.m. Roos, MD, PhD ; Elske Sieswerda, MD, PhD ; Elvira C.
3
3
1
3
van Dalen, MD, PhD ; Cecile M. Ronckers, PhD ; Foppe Oldenburger, MD ; Huib N. Caron, MD, PhD ; Caro
1
3
C.E. Koning, MD, PhD ; and Leontien C.M. Kremer, MD, PhD, Department of Radiation Oncology,
1
Academic Medical Center (AMC), Amsterdam, Netherlands ; Department of Medical Oncology, AMC,
2
Amsterdam, Netherlands ; and Department of Pediatric Oncology, Emma Children’s Hospital / AMC,
Amsterdam, Netherlands
3
Purpose: To evaluate the incidence and severity of symptomatic cerebrovascular accidents (CVAs)
in long-term childhood cancer survivors treated with cranial and supradiaphragmatic radiation therapy
(CRT, SDRT) and to assess dose-effect relationships. Patients and Methods: The single-center study cohort
included 1362 five-year survivors treated for a wide range of childhood cancer types. Physical radiation
doses for CRT and SDRT were converted into the equivalent dose in 2-Gy fractions (EQD2). Multivariable
Cox regression analyses were used to assess dose-effect relationships adjusting for sex, age at diagnosis,
