Differences in sonographic conspicuity according to papillary thyroid cancer subtype: results of the Ukrainian-American cohort study after the Chornobyl accident.
OBJECTIVE
Over time, the histology of papillary thyroid cancers detected in a repeatedly screened population exposed to radiation at Chornobyl (Chernobyl) has shifted from a more aggressive subtype toward less aggressive subtypes. This change may reflect biologic behavior but could also be influenced by the detectability of different subtypes. The study objective was to identify whether there is any relationship between the conspicuity of sonographically detected papillary cancers and histologic subtype.


METHODS
Sonographic images of 84 papillary cancers occurring in young people exposed to radiation at Chornobyl were each given a conspicuity score using a subjective 1-5 scale by four independent expert readers blinded to histologic subtype. The effects of tumor subtype, tumor encapsulation, reader, machine type, and nodule size on sonographic conspicuity were determined using analysis of variance and Spearman correlations.


RESULTS
Cancer subtype was related to sonographic conspicuity (p < 0.01). The relatively aggressive solid subtype of papillary carcinoma was more conspicuous than the papillary, follicular, and mixed subtypes (p < 0.05). The other subtypes did not differ significantly from each other in conspicuity. Conspicuity was not significantly related to nodule size, degree of encapsulation, age and sex of the subject, or machine type. Although the mean conspicuity score for each reader differed significantly, reliability of conspicuity judgments across readers was fair.


CONCLUSIONS
In subjects exposed to radiation from the Chornobyl accident, the solid subtype of papillary carcinoma appears to be more conspicuous on sonography than the other subtypes. Therefore, the change in subtype observed over time in this repeatedly screened population may be influenced by differences in nodule conspicuity.
O'Kane
Patrick
P
Department of Radiology, Thomas Jefferson University Hospital, 10th St. and Walnut St., 796 Main Bldg., Philadelphia, PA 19107, USA. patrick.okane@jefferson.edu
Shelkovoy
Evgeniy
E
McConnell
Robert J
RJ
Shpak
Victor
V
Parker
Laurence
L
Bogdanova
Tatiana I
TI
Brenner
Alina
A
Naida
Yuri
Y
Frangos
Andrea
A
Zablotska
Lydia
L
Robbins
Jacob
J
Greenebaum
Ellen
E
Zurnadzhy
Lydia Y
LY
Tronko
Mykolo
M
Hatch
Maureen
M
D000231:Adenocarcinoma, Papillary / Q000000981:diagnostic imaging* / Q000473:pathology*; D047852:Chernobyl Nuclear Accident; D015331:Cohort Studies; D009381:Neoplasms, Radiation-Induced / Q000000981:diagnostic imaging* / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013223:Statistics as Topic; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D014455:Ukraine; D014463:Ultrasonography / Q000379:methods*; D014481:United States