Prostate cancer incidence had a sharp rise over the last decade in western countries because of the increasing use of prostate-specific antigen (PSA) screening tests. According to Surveil876 CORRESPONDENCE
Journal of the National Cancer Institute, Vol. 93, No. 11, June 6, 2001
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Prostate Cancer: Different Incidence But Not Mortality Trends Within Two Areas of Tuscany, Italy
lance, Epidemiology, and End Results (SEER)1 data, standardized (1970 U.S. standard population) incidence rates for prostate cancer increased among white males by 70% from 1980 to 1990. The differences in the onset and extent of such a rise are most likely caused by the differences in the availability and use of PSA screening tests, introduced in the United States in the early 1980s and a few years later in Europe (1,2). Early detection of prostate cancer by PSA screening implies a long detection lead time and is certainly associated with overdiagnosis (3). Thus, no effect on mortality may be predicted simply on the basis of early detection (and of the consequent rise in incidence), and longterm controlled trials are ongoing in the United States (4) and in Europe (5). The issue of mortality reduction by screening has been addressed in the News section of the Journal (6) when the results of an ongoing screening program in some areas of Tyrol in Austria were mentioned, and it was noted that the observed reduction in prostate cancer mortality “was widely assumed to be a result of screening, . . . , although it is difficult, given the lead time, to explain how the effect could be seen so quickly.” Data from our cancer registry suggest another point of view and thus we warn about the risk of misinterpreting a reduction in prostate cancer mortality related to recent screening activity. Within Tuscany, central Italy, the Tuscany Cancer Registry (RTT)—a population-based cancer registry—has been active since 1984 (7). The RTT area corresponds to two administrative provinces, Florence (resident population from the 1991 census ⳱ 946 180 inhabitants) and Prato (216 713 inhabitants). Mortality figures for these provinces are available from the Regional Mortality Registry since 1985. Incidence rates from 1985 through 1997 and mortality rates from 1985 through 1998 (directly standardized to the European population), their 95% confidence intervals (CIs), percent change (PC, the percent difference of the mean of the rates of the last 2 years minus that of the first 2 years considered), and expected annual percent change (EAPC) were computed with the SEER*Stat software (
[email protected]). Prostate cancer incidence had a strong rise in the early 1990s, but trends were quite different in the two provinces. In Prato, the
dence but did not show statistically significant differences in prostate cancer mortality. EMANUELE CROCETTI STEFANO CIATTO MARCO ZAPPA
REFERENCES (1) Levi F, La Vecchia C, Randimbison L, Erler G, Te VC, Franceschi S. Incidence, mortality and survival from prostate cancer in Vaud and Neuchatel, Switzerland, 1974–1994. Annals of Oncology 1998;9:31–5. (2) Barchielli A, Crocetti E, Zappa M. Has the PSA wave already crashed upon us? Changes in the epidemiology of prostate cancer from 1985 to 1994 in central Italy [letter]. Ann Oncol 1999;3:361–2. (3) Zappa M, Ciatto S, Bonardi R, Mazzotta A. Overdiagnosis of prostate carcinoma by screening: an estimate based on the results of the Florence Screening Pilot Study. Ann Oncol 1998;9:1297–300. (4) Gohagan JK, Prorok PC, Kramer BS, Cornett JE. Prostate cancer screening in the prostate, lung, colorectal, and ovarian cancer screening trial of the National Cancer Institute. J Urol 1994;152(5 Pt 2):1905–9. (5) Auvinen A, Rietbergen JB, Denis LJ, Schroder FH, Prorok PC. Prospective evaluation plan for randomised trials of prostate cancer screening. The International Prostate Cancer Screening Trial Evaluation Group. J Med Screen 1996;3:97–104. (6) Reynolds T. Prostate cancer: numbers may not tell the whole story [news]. J Natl Cancer Inst 2000;92:1873–6. (7) Buiatti E, Balzi D, Barchielli A, Carli S, Crocetti E, Giovannetti L. Registro tumori toscano. In: Parkin DM, Whelan SL, Ferlay J, Raymond L, Young J, editors. Cancer incidence in five continents. Vol. VII. Lyon (France): IARC Sci Publ 1997;143:526–9.
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incidence was almost stable (PC ⳱ −3.5%; EAPC ⳱ −0.5% [95% CI ⳱ −2.3% to 1.4%]), whereas in Florence, the incidence increased by 75.3% from the years 1985 and 1986 (mean rate ⳱ 35.1 cases of prostate cancer per 100 000 men) to the years 1996 and 1997 (mean rate ⳱ 61.4 cases per 100 000 men; EAPC ⳱ 5.2% [95% CI ⳱ 4.1% to 6.3%]), with a sharp rise beginning around 1990. During the same period, mortality rates in Prato decreased by 10.4% (for 1985 and 1986, mean rate ⳱ 19.9; for 1997 and 1998, mean rate ⳱ 17.9), with a −2% EAPC, but the difference was not statistically significant (95% CI ⳱ −5.1% to 1.2%) for the relatively small sample size. In Florence, the decrease in mortality was smaller (−6.6%), but the larger sample allowed for statistical significance (EAPC ⳱ −1.1%; 95% CI ⳱ −2% to −0.1%). These data provide evidence that prostate cancer mortality was reduced by almost the same amount in these two adjacent areas, with one area (Prato) showing no simultaneous increase in incidence. The mortality reduction in Prato was not an effect of screening, because no official screening program existed, and opportunistic PSA-related screening of a population with a relevant size would have been revealed by an increase in incidence. Mortality reduction may have different explanations (e.g., prolonged survival because of better treatment of advanced disease). This is also the most likely case for Florence, where mortality decrease was constant, and incidence rose sharply only in the second half of the study period. The observed increase in incidence is most likely explained as a consequence of opportunistic PSA screening. Unfortunately, only sparse data on the diffusion of PSA in the RTT area are available and only for recent years from the province of Florence. Such preliminary information for the year 2000, based on the regional archive of diagnostic procedures, shows that the proportion of residents in the province of Florence who had a PSA test at least one time during that year was 11.6% for those aged 50–59 years, 26.8% for those aged 60–69 years, 37.6% for those aged 70–79 years, and 28.2% for those 80 years or older. A comparison of data from the RTT from the two areas showed a strikingly different trend for prostate cancer inci-
NOTES 1
Editor’s note: SEER is a set of geographically defined, population-based, central cancer registries in the United States, operated by local nonprofit organizations under contract to the National Cancer Institute (NCI). Registry data are submitted electronically without personal identifiers to the NCI on a biannual basis, and the NCI makes the data available to the public for scientific research. Affiliations of authors: E. Crocetti, M. Zappa (Unit of Clinical and Descriptive Epidemiology), S. Ciatto (Unit of Diagnostic Imaging), Centro per lo Studio e la Prevenzione Oncologica, Florence, Italy. Correspondence to: Emanuele Crocetti, M.D., Unit of Clinical and Descriptive Epidemiology, Centro per lo studio e la Prevenzione Oncologica, Via di San Salvi 12, 50135 Florence, Italy (e-mail:
[email protected]).
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