Overdiagnosis of Thyroid Cancer in the Marne and Ardennes Departments of France From 1975 to 2014
Overdiagnosis of Thyroid Cancer in the Marne and Ardennes Departments of France From 1975 to 2014
Introduction - Incidence of thyroid cancer has increased considerably in France in recent
 years, but the mortality rate has declined only slightly. Part of this increased incidence
 could be attributable to overdiagnosis. We aimed to estimate the contribution of
 overdiagnosis to the incidence of papillary thyroid cancer.

 Material and methods. - Incidence rates were calculated based on data from the specialised
 Marnes-Ardennes thyroid cancer registry, for cancers diagnosed between 1975 and 2014, by age
 category and by five-year period. The population was divided into two groups according to
 pTNM classification at diagnosis (i.e. localised or invasive). Overdiagnosis was defined as
 the difference in incidence rates between the invasive cancer and localised cancer groups.
 This rate was then divided by the incidence rate in the localised cancer group for the most
 recent period (2010-2014) to obtain the proportion of cancers attributable to overdiagnosis.
Introduction - Incidence of thyroid cancer has increased considerably in France in recent
 years, but the mortality rate has declined only slightly. Part of this increased incidence
 could be attributable to overdiagnosis. We aimed to estimate the contribution of
 overdiagnosis to the incidence of papillary thyroid cancer.

 Material and methods. - We included all subjects living in the Marne or Ardennes Departments
 of France and who were diagnosed with papillary thyroid cancer between 1975 and 2014. We
 recorded socio-demographic variables, i.e. age at diagnosis and sex. Cancer characteristics
 were also recorded, namely year of diagnosis, International Classification of Diseases (ICD)
 10th revision code associated with the papillary cancer, and the pTNM 2002 status. Incidence
 rates were calculated based on data from the specialised Marnes-Ardennes thyroid cancer
 registry, for cancers diagnosed between 1975 and 2014, by age category and by five-year
 period. The population was divided into two groups according to pTNM classification at
 diagnosis (i.e. localised or invasive). Overdiagnosis was defined as the difference in
 incidence rates between the invasive cancer and localised cancer groups. This rate was then
 divided by the incidence rate in the localised cancer group for the most recent period
 (2010-2014) to obtain the proportion of cancers attributable to overdiagnosis.
Inclusion Criteria:

 -  clinical doagnosis of papillary thyroid cancer

 -  living in the Marne or Ardennes departments of France

 Exclusion Criteria:

 - cancer stage not determined