Table 2.

Populations and study design, outcomes and ascertainment methods, IARC classification of registry quality, exposure and follow-up periods in 26 low-dose radiation epidemiological studies

Study name and reference	Design, censoring, matching	Specific outcome evaluated	Numbers of cases and numbers of controls; outcomes and cohort size,	Cancer ascertainment method	IARC classification; mortality: 1–6; incidence: A-G*	Exposure period	Follow-up period
Environmental
Chernobyl-exposed children (1)	Case-control; matched regional clinic controls	Childhood leukemia incidence (<6 y ATA)	421 acute leukemia cases vs 842 controls	Hospital records, population-based cancer registries	A: Belarus (after 1997) and Ukraine; NA: Russian Federation	1986–2000	1986–2000
TMI residents (2)	Cohort study; TMI population registry enrolled 93% residents living within 5 miles; study end or cancer diagnosis	Incidence of all and selected malignancies, including leukemia	1651 total incident malignancies, 56 incident leukemias in 22 069 TMI cohort members	TMI population registry matched annually with PA cancer registry	A: PA state cancer registry designated gold-level standard	1979	1982–1995
Chinese background (3)	Cohort study in high background and low background regions; in 1979, village household registry established to ascertain mortality	Mortality for all cancers, excluding leukemia and for leukemia	956 total cancer deaths (of 6005 total deaths), 15 leukemias in 736 942 p-y follow-up	Household surveys, medical records of deceased, village doctors, family and next of kin	4: Incomplete vital registration	1905–1998	1979–1998
GB background (4)	Case-control; matched controls from same birth registry	Childhood cancer incidence	27 447 total incident cancers (9058 leukemias) vs 36 793 controls with all cancers (11 912 leukemias)	National cancer registry	A: High-quality national	1991–1996	1980––2006
Swiss children background (5)	Cohort study from persons in 1990 and 2000 censuses; death, study end, age 16 y, emigration	Childhood cancer incidence	1782 cancers, 530 leukemias among 2 093 660 children	National cancer registry	B: High-quality regional	1974–2008	1990–2008
Techa River residents (6)	Cohort study of residents near Techa River or in Chelyabinsk City during some or all of 1956–2007; death, study end, emigration	Solid cancer incidence	1933 solid cancers among 12 759 cohort members	Medical records from oncology dispensaries, regional oncology clinics, health centers, and death certificates; death certificate-only diagnoses were 19% (range 4–56%) by subtype	2: Medium-quality vital registration	1951–2007	1956–2007
Finnish background (7)	Nested case-control study; matched population register controls	Childhood leukemia incidence	1039 cases vs 3279 controls	National cancer registry	A: High-quality national	1990–2011	1990–2011
Taiwanese residents (8)	Cohort study; cancer diagnosis, death, study end	Cancer incidence	111 cancers excluding leukemia (6 leukemias identified in 6242 persons with residential radiation exposure history who were followed-up)	National cancer registry	A: Currently; population cancer registry established in 1979 with notable improvement in quality over time	1982–1992	1983–2012
Medical
Cardiovascular imaging patients (9)	Cohort study: constructed from hospital discharge summary Quebec province-wide database	Cancer incidence; groupings by general anatomic sites but not type-specific	12 020 incident cancers in 82 861 patients (77% underwent ≥ 1 cardiac imaging or therapeutic procedure)	Hospital admission and outpatient visits; review of diagnostic codes	Not applicable because hospital and outpatient clinic records were source of outcomes	1996–2006	1996–2006
French pediatric CT (10)	Cohort study: children who had first CT scan ≤10 y old identified from 23 radiology departments nationwide; cancer diagnosis, death, study end	Cancer incidence in children focusing on CNS, leukemia, lymphoma	27 CNS, 25 leukemia, 21 lymphomas among 67 274 in cohort	National registry of childhood cancers	A: High-quality national; 2 = medium quality for vital status	2000–2010	2000–2011
UK pediatric CT (11)	Cohort study: children with first CT scan ≤22 y old identified from electronic radiology information systems at 81 hospitals throughout GB within National Health Service; cancer diagnosis, death, study end	Cancer incidence in children focusing on leukemia, MDS, CNS	65 leukemias, 9 MDS, 135 CNS among 178 604 in cohort	National cancer registry, national mortality data, pathology reports from cancer registries and hospitals	A: High-quality national	1980–2002	1980–2008
PIRATES (low dose) (12)	Pooled data from 9 cohort studies of those undergoing irradiation in childhood: incident thyroid cancer, death, loss to follow-up	Thyroid cancer incidence	252 cases in 2 588 559 p-y of follow-up in irradiated (184 cases in 2 114 683 p-y of follow-up for <0.1 mSv), 142 cases in 1 865 957 p-y of follow-up in nonirradiated cases	National cancer registries for 5 Nordic countries, hospital based for other 4 studies	Variable: national, regional, some not available	1926–2000	1935–2009
Occupational
Korean radiation workers (13)	Cohort study: assembled from central registry for radiation workers (legally mandated medical surveillance for radiation workers)	Cancer incidence (total and 6 specific types) and mortality	935 deaths (256 total cancers, 9 leukemias) and 564 total incident cancers (14 leukemias) in 79 679 radiation workers vs 206 deaths (53 cancers) and 254 incident cancers in 190 816 auto manufacturing workers	Deaths: Korean National Statistical Office registry (>95% registration); incident cancers: national health insurance claim data (>99% complete)	1: High-quality complete vital registration Not applicable for incidence because insurance claim data were used instead of national cancer registry	1984–2004	I: 2000–2005 M: 1992–2004
Belarus, Russia, and Baltic CL (14)	Nested case-control study within 66 000 Belarus, 65 000 Russian, and 15 000 liquidators from Baltic countries; each case matched on age to 4 controls from liquidator population	Hematologic neoplasm incidence	117 incident hematologic neoplasms (69 leukemias, 34 non-Hodgkin lymphoma and 14 others); analyses restricted to 70 cases (40 leukemias, 20 NHL, and 10 others) with reliable work information; outcomes reviewed by expert international pathologists’ panel	National cancer registries in Belarus and Baltic countries, National Medical Dosimetry Registry in Russia, and Registry of Hematologic Disorders in Belarus	A: Belarus and Baltic countries; not applicable in Russia	1986–1987	1986–2006
UK NRRW NW (15)	Cohort study: population identified from UKNRRW; cancer diagnosis, death, and end of follow-up	Total cancer incidence and total, excluding leukemia, and most specific neoplasms; mortality from all causes and most specific neoplasms	26 731 deaths (8107 cancers, 216 leukemias) in 3 301 400 p-y of follow-up; 11 113 incident cancers, 267 leukemias	National cancer registry	1: High-quality complete vital status A: High-quality national cancer registration	1946–2001	mortality:   1965–2001;   incidence:   1971-2001
Korean male NP NW (16)	Cohort study: assembled from nuclear workers at 20 plants who were issued dosimeters during 1978–2005; comparison group worked at same facilities but not issued a dosimeter; cohort members invited to participate in survey and clinical evaluation during 1992–2005	Total cancer incidence and total excluding leukemia, leukemia and 4 other types of neoplasms	96 cancers excluding leukemia (3 leukemias) identified in 8429 radiation workers and 101 cancers excluding leukemia (3 leukemias) in 7807 unmonitored workers	Korean Central Cancer Registry	A: High-quality national cancer registry	1978–2005	1992–2005
Rocketdyne NW (17)	Cohort study: identified from work history cards, electronic files, and radiation monitoring files from Radiation and Health and Safety Department; compared with workers at same facilities not monitored for radiation; death, age 95 y, loss to follow-up or end of study	Mortality from all causes, all cancers, leukemia, and most specific cancer types	2354 deaths (672 total cancers, 33 leukemias) among 5743 radiation workers with 194 731 p-y of follow-up compared with 14 854 deaths (4163 cancers) among 41 169 unmonitored workers with 1 392 648 p-y of follow-up	Linkage of cohort with NDI, California Death statistical Master File, SSA death master file, other SSA files and commercial information service providers	1: High-quality national vital status information	1948–1999	1948–2008
Japanese male NW (18)	Cohort study: nuclear workers identified from radiation worker registry; death, study end, date last known alive	Mortality from all causes, total cancers excluding leukemia, leukemia and some other selected cancer types	2703 total cancers (2636 total cancers excluding leukemia, 80 leukemias) in 200 583 male workers with 1 373 000 p-y of follow-up	Deaths identified from residence registration cards (vital status) and linked with vital statistics death records (cause of death)	3: Low-quality complete vital status registration	1957–2002	1991–2002
Canadian NW (19)	Cohort study; nuclear workers identified from National Dose Registry of all radiation-exposed workers	Mortality from all solid cancers and all excluding leukemia, leukemia	437 solid cancers and 21 leukemias in 45 656 nuclear workers	Deaths identified from historic summary tax file and Canadian Mortality Data Base	1: High-quality national vital status information	1956–1994	1956–1994
Ukrainian CL (20)	Nested case-control study: identified from 110 645 Ukrainian liquidators in Chernobyl State Registry of Ukraine; controls matched 5:1 (on place of residence, alive at corresponding case diagnosis, and year of birth using incidence density sampling	Incidence of leukemia and other hematologic neoplasms	162 leukemias	Potential leukemia cases in worker cohort identified from all health care institutions in study area during 1986–2000; cases diagnosed 2001–2006 identified from linkage of worker cohort with Ukrainian Cancer Registry	A: High-quality national level since 1997	1986–1987	1986–2006
German NP NW (21)	Cohort study: identified from comprehensive accident insurance and prevention list; death, study end, last available information date	Mortality from all cancers, total cancers excluding leukemia, solid cancers and cancer groupings related to exposure	126 total cancer deaths; 7 deaths from leukemia	Causes of death from federal and state vital statistics offices	2: Medium-quality vital registration	1966–2008	1991–2008
US NW (22)	Pooled cohort: assembled from 5 previously studied cohorts (employed >30 d, ever monitored, hired between facility start-up or when work history records first available); death, study end for those alive ≥1979 or last employment date when last known alive <1979	Mortality from all causes, all cancers excluding leukemia, leukemia, several specified cancers, and cancer groupings related to exposures	10 389 (9979 excluding leukemia and 410 leukemias) in 119 196 workers with 2 664 782 p-y of follow-up	Mortality and cause-of-death from previous studies used and extended through 2005 with linkage to SSA Death Master File and national tax records to confirm vital status; cause of death from NDI	1: High-quality vital registration	1944–2005	1944–2005
INWORKS NW (23, 24)	Pooled cohort: assembled from updated cohorts of nuclear workers from France, UK, and US; date of death, study end, loss to follow-up	Mortality from all cancer, all cancer other than leukemia, and all solid cancer; mortality from leukemia excluding CLL	19 748 all cancers (19 064 cancers other than leukemia, 17 957 solid cancers) among 308 297 workers with 8.2 million p-y of follow-up; 531 leukemias excluding CLL	Linkage with national and regional death registries, employer records, and SSA and NDI	1: UK and USA; 2: France	1944–2005	1944–2005
US atomic veterans (25)	Cohort study: assembled from Nuclear Test Review Program Information System; included military members from previous follow-up study; date of death, study end, loss to follow-up	Mortality from all causes of death, all cancers, leukemia and some other specific cancers	236 total cancers (19 leukemias) among 12 219 participants with 264 664 p-y of follow-up	Linkage of cohort with SSA Death Master ile and NDI; other sources included Internal Revenue Service, Department of Veterans Affairs Beneficiary Identification Record Location System	1: High-quality vital registration	1945–1963	1957–2010
USRT (26–28)	Cohort study: assembled from American Registry of Radiologic Technologists	Incidence and mortality of breast cancer, incidence of basal cell skin carcinoma, and mortality of brain cancer	1922 incident breast cancers among 66 915 female techs; 586 breast cancer deaths among 83 538 female techs; 3615 incident basal cell carcinomas of the skin among 65 719 Caucasian techs; 193 brain cancer deaths among 110 297 technologists	Self-report in 4 surveys with validation by medical records; linkage of cohort with SSA Death Master File and NDI	Breast cancer and basal cell carcinoma of the skin incidence: not applicable because based on self-report 1: High-quality vital registration	1916–1997	1983–2008
French NW (29)	Cohort study: pooled from 2 nuclear worker cohorts assembled in 1990s that were previously followed-up; death, study end, loss to follow up	Mortality from all causes, all solid cancers, leukemia and many other specific cancers	2356 solid cancers and 57 leukemias excluding CLL among 59 004 workers with 1 469 949 p-y follow-up	National death registry and self-report	2: Medium-quality vital status registration	1950–2004	1968–2004

*International Agency for Research on Cancer quality of estimates for mortality and incidence data by country. Mortality: 1 = high-quality vital registration; 2 = medium-quality vital registration; 3 = low-quality vital registration; 4 = incomplete vital registration; 5 = other sources; 6 = no data. Incidence: A = high-quality national or high-quality regional data (coverage >50%); B = high-quality regional (coverage >10%); C = high-quality regional data (coverage <10%); D = national data (population-based cancer registries); E = regional data (population-based cancer registries); F = frequency data (hospital based or pathology based); G = no data. GLOBOCAN 2012 Classification (http://globocan.iarc.fr/Pages/DataSource_and_methods.aspx. ATA = at the time of the accident; CL = Chernobyl Liquidator; CLL = chronic lymphocytic leukemia; CNS = central nervous system; CT = computed tomography; GB = Great Britain; I = incidence; IARC = International Agency for Research on Cancer; INWORKS = International Nuclear Workers Study; M = mortality; MDS = myelodysplastic syndromes; NDI = National Death Index; NP = nuclear power; NW = nuclear worker; PIRATES = Pooled International Radiation and Thyroid Cancer Epidemiology Studies; p-y = person-years; RBM = red bone marrow; RT = radiologic technologist; SSA = Social Security Administration; TMI = Three Mile Island; UKNRRW = United Kingdom National Registry for Radiation Workers; US = United States of America; USRT = United States Radiologic Technologists.