title: Breast cancer incidence trends in European women aged 20-39 years at diagnosis.
abstract: An increase in the incidence of breast cancer in women aged<40 years has been reported in recent years. Increased incidence could be partly explained by subtle detection biases, but the role of other risk factors cannot be ruled out. The purpose of the present study was to investigate the changes in temporal trends in breast cancer incidence in European women aged 20-39 years at diagnosis. Age specific breast cancer incidence rates for 17 European Cancer Registries were retrieved for the calendar period 1995-2006. Cancer registries data were pooled to reduce annual fluctuations present in single registries and increase incidence rates stability. Regression models were fitted to the data assuming that the number of cancer cases followed the Poisson distribution. Mean annual changes in the incidence rate (AIC) across the considered time window were calculated. The AIC estimated from all European registries was 1.032 (95% CI=1.019-1.045) and 1.014 (95% CI=1.010-1.018) in women aged 20-29 and 30-39 years old at diagnosis, respectively. The major change was detected among women aged 25-29 years at diagnosis: AIC=1.033 (95% CI=1.020-1.046). The upward trend was not affected when registries with high or low AIC were removed from the analysis (sensitivity analysis). Our findings support the presence of an increase in the incidence of breast cancer in European women in their 20s and 30s during the decade 1995-2006. The interpretation of the observed increase is not straightforward since a number of factors may have affected our results. The estimated annual increase in breast cancer incidence may result in a burden of the disease that is important in terms of public health and deserves further investigation of possible risk factors.
authors.affiliation: IRCCS AOU San Martino-IST-Istituto Nazionale per la Ricerca sul Cancro, Genoa, Italy., franco.merlo@istge.it
authors.forename: D F
authors.initials: DF
authors.lastname: Merlo
authors.forename: M
authors.initials: M
authors.lastname: Ceppi
authors.forename: R
authors.initials: R
authors.lastname: Filiberti
authors.forename: V
authors.initials: V
authors.lastname: Bocchini
authors.forename: A
authors.initials: A
authors.lastname: Znaor
authors.forename: M
authors.initials: M
authors.lastname: Gamulin
authors.forename: M
authors.initials: M
authors.lastname: Primic-Žakelj
authors.forename: P
authors.initials: P
authors.lastname: Bruzzi
authors.forename: C
authors.initials: C
authors.lastname: Bouchardy
authors.forename: A
authors.initials: A
authors.lastname: Fucic
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000175:diagnosis / Q000453:epidemiology*; D005060:Europe / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D016013:Likelihood Functions; D016012:Poisson Distribution; D012044:Regression Analysis; D012680:Sensitivity and Specificity; D055815:Young Adult