Incidence of thyroid cancer in Italy, 1991-2005: time trends and age-period-cohort effects.
BACKGROUND
In Italy, some of the highest incidence rates (IRs) of thyroid cancer (TC) worldwide have been reported.


METHODS
TC cases <85 years of age reported to Italian cancer registries during 1991-2005 were included. Age-standardized IRs were computed for all TC and age-period-cohort effects were estimated for papillary TC.


RESULTS
IRs of TC were twofold higher in 2001-2005 than in 1991-1995 (18 and 8 per 100,000 women, 6 and 3 per 100,000 men, respectively). Increases were similar in the two sexes and nearly exclusively due to papillary TC. Increases of papillary TC by birth cohort were found in both sexes and among all age groups between 20 and 79 years. Age-period-cohort models showed a strong period effect in both sexes (rate ratio for 2001-2009 versus 1991-1995 = 2.5 in women and 2.3 in men), although IRs peaked at an earlier age in women (45-49 years) than men (65-69 years).


CONCLUSIONS
The strength of the period effect in both sexes and the earlier onset in women than men strongly implicated increased medical surveillance in the upward trends of papillary TC incidence in Italy. The consequences of the current intense search for TC on morbidity and possible overtreatment, especially among young women, should be carefully evaluated.
Epidemiology and Biostatistics Unit, Aviano Cancer Center, IRCCS, Aviano; Department of Occupational Health, Section of Medical Statistics, Università degli Studi di Milano, Milan, Italy. Electronic address: epidemiology@cro.it.
L
L
Dal Maso
Epidemiology and Biostatistics Unit, Aviano Cancer Center, IRCCS, Aviano; International Agency for Research on Cancer, Lyon, France.
M
M
Lise
Veneto Cancer Registry, Istituto Oncologico Veneto IRCCS, Padua.
P
P
Zambon
Romagna Cancer Registry, Cancer Institute of Romagna (IRST), Meldola.
F
F
Falcini
Tuscany Cancer Registry, Cancer Prevention and Research Istitute (ISPO), Florence.
E
E
Crocetti
Epidemiology and Biostatistics Unit, Aviano Cancer Center, IRCCS, Aviano; Friuli Venezia Giulia Cancer Registry, Direzione Centrale della Sanità, Trieste.
D
D
Serraino
Modena Cancer Registry, Policlinico, Modena.
C
C
Cirilli
Piedmont Cancer Registry, City of Torino, Ospedale S. Giovanni Battista-CPO, Torino.
R
R
Zanetti
Liguria Cancer Registry, IST/Università di Genova, Genoa.
M
M
Vercelli
Ferrara Cancer Registry, Università di Ferrara, Ferrara.
S
S
Ferretti
Umbria Cancer Registry, Università di Perugia, Perugia.
F
F
Stracci
Parma Province Cancer Registry, Ospedale di Parma, Parma.
V
V
De Lisi
Latina Cancer Registry, AUSL Latina, Latina.
S
S
Busco
Lombardia Cancer Registry, Varese Province, Istituto Nazionale Tumori, Milano.
G
G
Tagliabue
Cancer Registry of Sassari, ASL1, Sassari.
M
M
Budroni
Cancer Registry and Histopathology Unit, Department of Oncology, 'Civile M.P.Arezzo' Hospital, ASP 7, Ragusa.
R
R
Tumino
Registro Tumori Piemonte, Provincia di Biella (CPO), Biella, Italy.
A
A
Giacomin
International Agency for Research on Cancer, Lyon, France.
S
S
Franceschi
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015988:Cohort Effect; D005260:Female; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D012042:Registries / Q000706:statistics & numerical data; D013964:Thyroid Neoplasms / Q000453:epidemiology*; D013997:Time Factors