Causes and mechanisms of the registered incidence increase of
pediatric thyroid carcinoma after the Chernobyl accident, unrelated to the
ionizing radiation, were recently reviewed by Z. Jaworowski (2010). The
main body of evidence (Cardis et al. 2005; Tronko et al. 2006; Davis et
al. 2004) in favor of the cause-effect relationship between ionizing
radiation and thyroid carcinoma among children and adolescents after the
Chernobyl accident is provided by the epidemiologic studies (Ron 2009).
The case-control study (Cardis et al. 2005) was based on a retrospective
estimation of doses by questioning. 'Chernobyl victim syndrome' (Bay and
Oughton 2005) was a widespread phenomenon: many patients strived for
higher dose estimations to support their status of Chernobyl victims, and
provided biased information. Cancer patients should have remembered
circumstances related to the exposure better than the controls. The study
by Davis et al. (2004) was similar in design. In the cohort study by
Tronko et al. (2006), along with questioning, the data of thyroid
dosimetry performed within the period of 2 months (a half-life of 131I is
about 8 days) after the accident were used for estimation of individual
doses. The study design included, if indicated, repetitive examinations in
the central clinics in Kiev (Tronko et al. 2006). Persons with higher dose
estimates must have been, on average, more interested in further
examinations. In the health care system of the former Soviet Union, an
extent of a medical checkup has sometimes depended on a patient's
initiative. The recent study (Zablotska et al. 2010) is analogous in
design to that by Tronko et al. (2006). Other epidemiologic studies were
probably loaded with these and other biases (Jaworowski 2010), typical for
research on stochastic effects of low level radiation (Watanabe et al.
2008). After the accident appeared many poorly substantiated publications,
where spontaneous diseases in Chernobyl clean-up workers or inhabitants of
radiocontaminated areas, sometimes quite distant from Chernobyl, were a
priori considered to be radiogenic (e.g. Grobova and Chernikov 1996;
Chuchalin et al. 1997; Kogan et al. 1999; Derizhanova 2000; Degtiarova
2000; Lysenko et al. 2000). Previously we discussed several publications
overestimating Chernobyl consequences (Jargin 2007; 2009a,b; 2010a,b).
Unreliability of other reports can be assumed by analogy: if earlier
papers on the same topic were unreliable, later ones might be unreliable
as well, because motivations and the attitude to the topic remained
unchanged. For an inside observer it is obvious that behind the avalanche
of predominantly Russian-language papers overestimating Chernobyl
consequences, some of them referenced in Yablokov (2010), was a directive,
which had been not uncommon for the Soviet science. In the former Soviet
Union, research themes were often assigned to the scientists, while
"expected results" were discussed at Scientific Councils (uchenyi soviet)
sometimes being, in fact, prescribed in advance. Desired research results
could be directly "recommended" by a superior, which was favored by the
ingrained authoritative management style. Manipulations with statistics
and other forms of scientific misconduct were known to occur in medical
research from of old (Jargin 2009c,d; 2010b-d). Motives for Chernobyl
consequences overestimation have been obvious: exaggeration of this theme
facilitated writing of dissertations, financing, international help, etc.
Chernobyl accident has been exploited to strangle worldwide development of
atomic energy (Jaworowski 2010) thus contributing to elevation of oil
prices.
Travelling to the areas, formerly contaminated due to the
Chernobyl accident, the author of this letter interviewed pathologists,
cytologists and other specialists, who participated in diagnostics of the
post-Chernobyl tumors. Most of them agreed that Chernobyl consequences had
been overestimated; and the role of vested interests was pointed out. It
was also stated that sets of histological specimens from a single patient
were sometimes subdivided into several ones, creating "dead souls" (Gogol
1842), which has influenced statistics. It can be verified by DNA
examination of the specimens accumulated in tissue banks. Radio- and
cancerophobia, sometimes amounting to panic, contributed to the
overdiagnosis of cancer, which can be illustrated by the following
passages from a Russian-language professional publication (verbatim
translation): "Practically all nodular thyroid lesions, independently of
their size, were regarded at that time in children as potentially
malignant tumors, requiring an urgent surgical operation" or
"Aggressiveness of surgeons contributed to the shortening of the minimal
latency period." (Parshkov 2006). Mechanisms of overdiagnosis were
discussed previously (Jargin 2009e; 2010a). Obviously, mass screening in
the areas, where pediatric thyroid cancer had been rarely diagnosed
before, on the background of poor equipment and shortage of modern
literature, in the atmosphere of radio- and cancerophobia, of vested
interests both in decision-making spheres and among researchers, must have
inevitably resulted in overestimation. The principal cause of Chernobyl
consequences overestimation remains to be pointed out: it is unreliability
of Chernobyl-related (and some other) research originating from the former
Soviet Union, a nonchalant attitude towards scientific misconduct in
general and manipulations with statistics in particular (Jargin 2009c,d;
2010b-d). The true state of affairs will be cleared sooner or later:
Chernobyl cancer specimens are preserved in tissue banks, and evaluation
of time-related markers of tumor dedifferentiation will allow one day to
estimate a true "age" of these tumors and to demonstrate, how many of them
had developed before the accident, being then misclassified as radiogenic
cancer. More difficult it would be to identify cases from non-contaminated
areas falsely registered as Chernobyl victims, because it would require
cooperation of the authorities, but this problem is technically solvable
as well. A concluding point is that overestimation of Chernobyl
consequences can create a wrong concept about carcinogenic action of
radioactive iodine, which can be harmful for research and practice.
References
Bay IA and Oughton DH. 2005. Social and economic effects. In: Smith
J, Beresford NA. Chernobyl - Catastrophe and Consequences, pp 239-266.
Springer, Chichester
Cardis E, Kesminiene A, Ivanov V, et al. 2005. Risk of thyroid cancer
after exposure to 131I in childhood. J Natl Cancer Inst 97:724-732
Chuchalin AG, Maracheva AV, Grobova OM, et al. 1997. Lungs exposed to
nuclear catastrophe: one-year therapeutic programme in Chernobyl
liquidators group. Swiss Med Wkly 127:165-169
Degtiarova LV. 2000. A Possibility of Gastric Cancer and Malt-
Lymphomas Appearance in Persons Affected because of Chernobyl Accident.
XXIII International Congress of the International Academy of Pathology and
14th World Congress of Academic and Environmental Pathology. 15-20 October
2000. Nagoya, Japan. Pathol Int. 50 Suppl. Abstract P-19-31.
Derizhanova IS. The Pulmonary-Renal Syndrome among Chernobyl Nuclear
Accident Liquidators. XXIII International Congress of the International
Academy of Pathology and 14th World Congress of Academic and Environmental
Pathology. 15-20 October 2000. Nagoya, Japan. Pathol Int. 50 Suppl.
Abstract P-19-34.
Grobova OM and Chernikov VP. 1996. The presence of cesium-137 in the
tissue of a lung tumor in someone who cleaned up the aftermath of the
accident at the Chernobyl Atomic Electric Power Station (in Russian with
English summary). Ter Arkh 68(3):26-30.
Davis S, Stepanenko V, Rivkind N, et al. 2004. Risk of thyroid cancer
in the Bryansk Oblast of the Russian Federation after the Chernobyl Power
Station accident. Radiat Res 162(3):241-248
Gogol NV. 1842. Dead Souls (in Russian). Possev, Moscow
Jargin SV. 2007. Over-estimation of radiation-induced malignancy after the
Chernobyl accident. Virchows Arch 451(1):105-106
Jargin SV. 2009a. Overestimation of Chernobyl consequences:
biophysical aspects. Radiat Environ Biophys 48(3):341-344
Jargin SV. 2009b. Overestimation of Chernobyl consequences:
calculation of a latent period for tumors with unproven radiation
etiology. Radiat Environ Biophys 48:433-434
Jargin SV. 2009c. Russian pathology and scientific misconduct. Indian
J Pathol Microbiol 52(3):443
Jargin SV. 2009d. Manipulation with statistics in medical research.
Dermatopathol: Pract & Conc 15(1):21. Available at http://derm101.com/abstract/32761
Jargin SV. 2009e. Overestimation of thyroid cancer incidence after
Chernobyl. Health Phys 96(2):186
Jargin SV. 2010d Plagiarism in radiology: A substitute for
importation of foreign handbooks. J Med Imaging Radiat Oncol 54(1):50-52
Jaworowski Z. 2010. Observations on the Chernobyl Disaster and LNT.
Dose Response 8:148-171
Khmel'nitskii OK, Tret'iakova MS, Kiselev AV, et al. 2000. Morpho-
ecological characteristics of thyroid diseases in various regions of
Russia and Belorussia from surgical data (in Russian with English
summary). Arkh Patol 62(4):19-27.
Kogan EA, Cherniaev AL, Chuchalin AG, et al. 1999. Morphologic and
molecular-genetic characterization of lung cancer developing in people who
have worked at nuclear facilities and who have lived in Russian
territories polluted after the accident at the Chernobyl power plant. (in
Russian with English summary). Arkh Patol 61(1):22-26.
Lysenko AI, Kirpatovski? ID and Pisarenko SS. 2000. Morphological
changes in male sexual glands in Kaluga regions contaminated with
radionuclides (in Russian with English summary). Arkh Patol 62(4):27-31
Parshkov EM. 2006. Analysis of thyroid cancer morbidity. In:
Lushnikov EF Tsyb AF, Yamashita S. Thyroid cancer in Russia after the
Chernobyl. pp 36-59. Meditsina: Moscow (in Russian with English summary)
Ron E. 2009. Response to Jargin. Health Phys 96:186-187
Tronko MD, Howe GR, Bogdanova TI, et al. 2006. A cohort study of
thyroid cancer and other thyroid diseases after the Chornobyl accident:
thyroid cancer in Ukraine detected during first screening. J Natl Cancer
Inst 98:897-903
Watanabe T, Miyao M, Honda R and Yamada Y. 2008. Hiroshima survivors
exposed to very low doses of A-bomb primary radiation showed a high risk
for cancers. Environ Health Prev Med 13:264-270
Yablokov AV. 2010. Oncological diseases after the Chernobyl
catastrophe. Ann N Y Acad Sci 1181:161-191
Zablotska LB, Ron E, Rozhko AV, et al. 2010. Thyroid cancer risk in
Belarus among children and adolescents exposed to radioiodine after the
Chornobyl accident. Br J Cancer. Nov 23. [Epub ahead of print]
Rapid Response:
Thyroid cancer after Chernobyl: befogged truth
Causes and mechanisms of the registered incidence increase of
pediatric thyroid carcinoma after the Chernobyl accident, unrelated to the
ionizing radiation, were recently reviewed by Z. Jaworowski (2010). The
main body of evidence (Cardis et al. 2005; Tronko et al. 2006; Davis et
al. 2004) in favor of the cause-effect relationship between ionizing
radiation and thyroid carcinoma among children and adolescents after the
Chernobyl accident is provided by the epidemiologic studies (Ron 2009).
The case-control study (Cardis et al. 2005) was based on a retrospective
estimation of doses by questioning. 'Chernobyl victim syndrome' (Bay and
Oughton 2005) was a widespread phenomenon: many patients strived for
higher dose estimations to support their status of Chernobyl victims, and
provided biased information. Cancer patients should have remembered
circumstances related to the exposure better than the controls. The study
by Davis et al. (2004) was similar in design. In the cohort study by
Tronko et al. (2006), along with questioning, the data of thyroid
dosimetry performed within the period of 2 months (a half-life of 131I is
about 8 days) after the accident were used for estimation of individual
doses. The study design included, if indicated, repetitive examinations in
the central clinics in Kiev (Tronko et al. 2006). Persons with higher dose
estimates must have been, on average, more interested in further
examinations. In the health care system of the former Soviet Union, an
extent of a medical checkup has sometimes depended on a patient's
initiative. The recent study (Zablotska et al. 2010) is analogous in
design to that by Tronko et al. (2006). Other epidemiologic studies were
probably loaded with these and other biases (Jaworowski 2010), typical for
research on stochastic effects of low level radiation (Watanabe et al.
2008). After the accident appeared many poorly substantiated publications,
where spontaneous diseases in Chernobyl clean-up workers or inhabitants of
radiocontaminated areas, sometimes quite distant from Chernobyl, were a
priori considered to be radiogenic (e.g. Grobova and Chernikov 1996;
Chuchalin et al. 1997; Kogan et al. 1999; Derizhanova 2000; Degtiarova
2000; Lysenko et al. 2000). Previously we discussed several publications
overestimating Chernobyl consequences (Jargin 2007; 2009a,b; 2010a,b).
Unreliability of other reports can be assumed by analogy: if earlier
papers on the same topic were unreliable, later ones might be unreliable
as well, because motivations and the attitude to the topic remained
unchanged. For an inside observer it is obvious that behind the avalanche
of predominantly Russian-language papers overestimating Chernobyl
consequences, some of them referenced in Yablokov (2010), was a directive,
which had been not uncommon for the Soviet science. In the former Soviet
Union, research themes were often assigned to the scientists, while
"expected results" were discussed at Scientific Councils (uchenyi soviet)
sometimes being, in fact, prescribed in advance. Desired research results
could be directly "recommended" by a superior, which was favored by the
ingrained authoritative management style. Manipulations with statistics
and other forms of scientific misconduct were known to occur in medical
research from of old (Jargin 2009c,d; 2010b-d). Motives for Chernobyl
consequences overestimation have been obvious: exaggeration of this theme
facilitated writing of dissertations, financing, international help, etc.
Chernobyl accident has been exploited to strangle worldwide development of
atomic energy (Jaworowski 2010) thus contributing to elevation of oil
prices.
Travelling to the areas, formerly contaminated due to the
Chernobyl accident, the author of this letter interviewed pathologists,
cytologists and other specialists, who participated in diagnostics of the
post-Chernobyl tumors. Most of them agreed that Chernobyl consequences had
been overestimated; and the role of vested interests was pointed out. It
was also stated that sets of histological specimens from a single patient
were sometimes subdivided into several ones, creating "dead souls" (Gogol
1842), which has influenced statistics. It can be verified by DNA
examination of the specimens accumulated in tissue banks. Radio- and
cancerophobia, sometimes amounting to panic, contributed to the
overdiagnosis of cancer, which can be illustrated by the following
passages from a Russian-language professional publication (verbatim
translation): "Practically all nodular thyroid lesions, independently of
their size, were regarded at that time in children as potentially
malignant tumors, requiring an urgent surgical operation" or
"Aggressiveness of surgeons contributed to the shortening of the minimal
latency period." (Parshkov 2006). Mechanisms of overdiagnosis were
discussed previously (Jargin 2009e; 2010a). Obviously, mass screening in
the areas, where pediatric thyroid cancer had been rarely diagnosed
before, on the background of poor equipment and shortage of modern
literature, in the atmosphere of radio- and cancerophobia, of vested
interests both in decision-making spheres and among researchers, must have
inevitably resulted in overestimation. The principal cause of Chernobyl
consequences overestimation remains to be pointed out: it is unreliability
of Chernobyl-related (and some other) research originating from the former
Soviet Union, a nonchalant attitude towards scientific misconduct in
general and manipulations with statistics in particular (Jargin 2009c,d;
2010b-d). The true state of affairs will be cleared sooner or later:
Chernobyl cancer specimens are preserved in tissue banks, and evaluation
of time-related markers of tumor dedifferentiation will allow one day to
estimate a true "age" of these tumors and to demonstrate, how many of them
had developed before the accident, being then misclassified as radiogenic
cancer. More difficult it would be to identify cases from non-contaminated
areas falsely registered as Chernobyl victims, because it would require
cooperation of the authorities, but this problem is technically solvable
as well. A concluding point is that overestimation of Chernobyl
consequences can create a wrong concept about carcinogenic action of
radioactive iodine, which can be harmful for research and practice.
References
Bay IA and Oughton DH. 2005. Social and economic effects. In: Smith
J, Beresford NA. Chernobyl - Catastrophe and Consequences, pp 239-266.
Springer, Chichester
Cardis E, Kesminiene A, Ivanov V, et al. 2005. Risk of thyroid cancer
after exposure to 131I in childhood. J Natl Cancer Inst 97:724-732
Chuchalin AG, Maracheva AV, Grobova OM, et al. 1997. Lungs exposed to
nuclear catastrophe: one-year therapeutic programme in Chernobyl
liquidators group. Swiss Med Wkly 127:165-169
Degtiarova LV. 2000. A Possibility of Gastric Cancer and Malt-
Lymphomas Appearance in Persons Affected because of Chernobyl Accident.
XXIII International Congress of the International Academy of Pathology and
14th World Congress of Academic and Environmental Pathology. 15-20 October
2000. Nagoya, Japan. Pathol Int. 50 Suppl. Abstract P-19-31.
Derizhanova IS. The Pulmonary-Renal Syndrome among Chernobyl Nuclear
Accident Liquidators. XXIII International Congress of the International
Academy of Pathology and 14th World Congress of Academic and Environmental
Pathology. 15-20 October 2000. Nagoya, Japan. Pathol Int. 50 Suppl.
Abstract P-19-34.
Grobova OM and Chernikov VP. 1996. The presence of cesium-137 in the
tissue of a lung tumor in someone who cleaned up the aftermath of the
accident at the Chernobyl Atomic Electric Power Station (in Russian with
English summary). Ter Arkh 68(3):26-30.
Davis S, Stepanenko V, Rivkind N, et al. 2004. Risk of thyroid cancer
in the Bryansk Oblast of the Russian Federation after the Chernobyl Power
Station accident. Radiat Res 162(3):241-248
Gogol NV. 1842. Dead Souls (in Russian). Possev, Moscow
Jargin SV. 2007. Over-estimation of radiation-induced malignancy after the
Chernobyl accident. Virchows Arch 451(1):105-106
Jargin SV. 2009a. Overestimation of Chernobyl consequences:
biophysical aspects. Radiat Environ Biophys 48(3):341-344
Jargin SV. 2009b. Overestimation of Chernobyl consequences:
calculation of a latent period for tumors with unproven radiation
etiology. Radiat Environ Biophys 48:433-434
Jargin SV. 2009c. Russian pathology and scientific misconduct. Indian
J Pathol Microbiol 52(3):443
Jargin SV. 2009d. Manipulation with statistics in medical research.
Dermatopathol: Pract & Conc 15(1):21. Available at
http://derm101.com/abstract/32761
Jargin SV. 2009e. Overestimation of thyroid cancer incidence after
Chernobyl. Health Phys 96(2):186
Jargin, SV. 2010a. Chernobyl-related Cancer: re-evaluation needed.
Turkish J Pathol 26(2):177-181. Available at
http://www.turkjpath.org/pdf/pdf_TPD_1440.pdf
Jargin SV. 2010b. Overestimation of Chernobyl consequences: poorly
substantiated information published. Radiat Environ Biophys 49(4):743-745
Jargin SV. 2010c. The heritage of Rudolf Virchow and the stem cell.
GMS Med Bibl Inf 2010;10(2):Doc14. Available at
http://www.egms.de/en/journals/mbi/2010-10/mbi000197.shtml
Jargin SV. 2010d Plagiarism in radiology: A substitute for
importation of foreign handbooks. J Med Imaging Radiat Oncol 54(1):50-52
Jaworowski Z. 2010. Observations on the Chernobyl Disaster and LNT.
Dose Response 8:148-171
Khmel'nitskii OK, Tret'iakova MS, Kiselev AV, et al. 2000. Morpho-
ecological characteristics of thyroid diseases in various regions of
Russia and Belorussia from surgical data (in Russian with English
summary). Arkh Patol 62(4):19-27.
Kogan EA, Cherniaev AL, Chuchalin AG, et al. 1999. Morphologic and
molecular-genetic characterization of lung cancer developing in people who
have worked at nuclear facilities and who have lived in Russian
territories polluted after the accident at the Chernobyl power plant. (in
Russian with English summary). Arkh Patol 61(1):22-26.
Lysenko AI, Kirpatovski? ID and Pisarenko SS. 2000. Morphological
changes in male sexual glands in Kaluga regions contaminated with
radionuclides (in Russian with English summary). Arkh Patol 62(4):27-31
Parshkov EM. 2006. Analysis of thyroid cancer morbidity. In:
Lushnikov EF Tsyb AF, Yamashita S. Thyroid cancer in Russia after the
Chernobyl. pp 36-59. Meditsina: Moscow (in Russian with English summary)
Ron E. 2009. Response to Jargin. Health Phys 96:186-187
Tronko MD, Howe GR, Bogdanova TI, et al. 2006. A cohort study of
thyroid cancer and other thyroid diseases after the Chornobyl accident:
thyroid cancer in Ukraine detected during first screening. J Natl Cancer
Inst 98:897-903
Watanabe T, Miyao M, Honda R and Yamada Y. 2008. Hiroshima survivors
exposed to very low doses of A-bomb primary radiation showed a high risk
for cancers. Environ Health Prev Med 13:264-270
Yablokov AV. 2010. Oncological diseases after the Chernobyl
catastrophe. Ann N Y Acad Sci 1181:161-191
Zablotska LB, Ron E, Rozhko AV, et al. 2010. Thyroid cancer risk in
Belarus among children and adolescents exposed to radioiodine after the
Chornobyl accident. Br J Cancer. Nov 23. [Epub ahead of print]
Competing interests: No competing interests