Journal of the National Cancer Institute Advance Access originally published online on November 27, 2007
JNCI Journal of the National Cancer Institute 2007 99(23):1817-1818; doi:10.1093/jnci/djm225
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© The Author 2007. Published by Oxford University Press.
CORRESPONDENCE |
Re: Breast Cancer Incidence, 1980–2006: Combined Roles of Menopausal Hormone Therapy, Screening Mammography, and Estrogen Receptor Status
Affiliations of authors: Unit of Epidemiology (AP, MT, NS) and Piedmont Cancer Registry (SR, RZ, FR), Centro per la Prevenzione Oncologica, Turin, Italy
Correspondence to: Antonio Ponti, MD, MPH, Centro per la Prevenzione Oncologica, Unit of Epidemiology, via S. Francesco da Paola, 31, Turin, TO 10123 Italy (e-mail: antonio.ponti{at}cpo.it).
In contrast to the results reported by Glass et al. (1), who showed a marked decrease in breast cancer incidence in 2003 in women members of the Kaiser Permanente Northwest prepaid health plan, we observed a drop in breast cancer incidence during 1999–2001 but not during 2001–2003 in the population of Turin, Italy. This city has been covered since 1985 by a population-based cancer registry that contributes to data published in the International Agency for Research on Cancer publication Cancer Incidence in Five Continents (2) and since 1992 by a centrally organized mammography screening program with personal invitations every 2 years to women aged 50–69 (3). Both activities are run under the responsibility of the Centro per la Prevenzione Oncologica, which maintains the respective computerized databases of individual records.
We analyzed invasive breast cancer incidence time trends in Turin from 1985 to 2003 (total number of cases = 13625). We used record linkage to investigate how the trend is affected by any changes in mammography screening. Our institution, as part of its duties in screening evaluation, is entitled to perform such a linkage under a waiver of written informed consent. Each individual breast cancer case was then categorized as screen detected at first screen, screen detected at subsequent screen, or not screen detected. We tabulated separately the incidence trends in the group of cancers obtained after the exclusion of all cases detected at first screen, the so-called unbiased set (4). Cases detected at the first test are likely to be composed predominantly of prevalent, slow-growing cases that, if mammography had not taken place, would have appeared clinically several years after screen detection.
In all ages combined, age-standardized incidence decreased at a statistically significant annual estimated percentage change of –2.6%, from 127.4 cases per 100000 in 1999 to 115.1 in 2003 (joinpoint regression). However, the decrease was steeper in the period 1999–2001 (–3.1%, from 127.4 to 119.5). This trend was restricted to women in the older age classes (Fig. 1). When all cases detected at the first screen were excluded, both the increasing time trend and the subsequent decrease almost completely flattened. Furthermore, the trend in the number of first screens strictly paralleled population cancer incidence, whereas the total number of screening mammographies did not (Fig. 1).
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Use of hormone replacement therapy by postmenopausal women is lower in Northern Italy than in United States, not exceeding 15% in the mid-90s (5). Although a reduction in hormone replacement therapy consumption has been indeed reported in Italy in 2002 and 2003 [estrogen prescriptions decreased nationwide by 15.3% and 18.0%, respectively, in those years (6)], it is therefore not surprising that this reduction has not translated in a marked decline in breast cancer incidence.
On the other hand, we believe that, in our data, the trend in invasive breast cancer incidence is largely explained by the slow increase during 1992–1999 of screen-detected cases at first screen and by their decrease thereafter. Such an interpretation may be relevant to other geographical areas in which organized or spontaneous screening reaches a plateau after an increase in the preceding years. Indeed, this possibility has been suggested, albeit with no support by record linkage, in relation to the American data (7). To verify this hypothesis, it would be of interest if Glass et al. could provide any information on the volume of screening mammographies for first and subsequent tests separately.
REFERENCES
(1) Glass AG, Lacey JV, Carreon JD, Hoover RN. Breast cancer incidence, 1980–2006: combined roles of menopausal hormone therapy, screening mammography, and estrogen receptor status. J Natl Cancer Inst (2007) 99:1152–61.
(2) Parkin DM, Whelan SL, Ferlay J, Teppo L, Thomas DB. Cancer incidence in five continents (2002) Vol. VIII. Lyon (France): International Agency for Research on Cancer.
(3) Giordano L, Giorgi D, Fasolo G, Segnan N, Del Turco MR. Breast cancer screening: characteristics and results of the Italian programmes in the Italian group for planning and evaluating breast cancer screening programmes (GISMa). Tumori (1996) 82:31–7.[Web of Science][Medline]
(4) Duffy SW, Tabar L, Fagerberg G, Gad A, Grontoft O, South MC, et al. Breast screening, prognostic factors and survival; results from the Swedish Two-County Study. Br J Cancer (1991) 64:1133–8.[Web of Science][Medline]
(5) Chiaffarino F, Parazzini F, La Vecchia C, Bianchi MM, Benzi G, Ricci E, et al. Correlates of hormone replacement therapy use in Italian women. Maturitas (1999) 33:107–15.[CrossRef][Web of Science][Medline]
(6) L’uso dei Farmaci in Italia, Rapporto Nazionale anno 2003. Roma: Ministero della Salute, Osservatorio Nazionale sull’Impiego dei Medicinali. (2004) p. 25 and 54. Available at: http://www.agenziafarmaco.it. [Last accessed: August 16, 2007.].
(7) Jemal A, Ward E, Thun MJ. Recent trends in breast cancer incidence rates by age and tumor characteristics among US women. Breast Cancer Res (2007) 9:R28.[CrossRef][Medline]
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