BERKELEY, CA (UroToday.com) - The incidence of prostate cancer in Sweden increased drastically between 1997 and 2004.
The main reason for the increase was an increased use of prostate-specific antigen (PSA) for early detection of prostate cancer. Despite that there was no national recommendation for prostate cancer screening in Sweden and there are no data on the occurence of PSA testing in Sweden. In order to estimate the uptake of PSA testing we calculated the use of the PSA test based on the incidence in Swedish counties, and data from a randomized population-based PSA screening trial in the Göteborg part of the ERSPC trial.1 In the screening group the number of screening visits (i.e. amount of PSA tests) are known as well as the resulting prostate cancer incidence and thus we could calculate how PSA testing influenced the incidence.
Since there was hardly any PSA testing during the 1980s, we used historical data on prostate cancer incidence between 1980 and 1990 for prediction of the prostate cancer incidence in Sweden without any PSA testing.
The calculated estimates showed a cumulated PSA uptake between 56 and 59% depending on the model used, and is at the same level as the proportion of men who had undergone PSA testing in the control group in the Prostate, Lung, Colorectal and Ovarian (PLCO) screening trial in the sixth year of follow-up.2 However, the yearly PSA uptake in Sweden showed considerable regional differences, ranging between 5 and 20%.
In our study, estimates were made for the annual uptake of PSA testing and the cumulated uptake of PSA testing. The assumptions made in the estimations introduce a degree of uncertainty since the actual PSA testing pattern is unknown. Therefore the cumulated number has to be interpreted with caution. However, the exact number of PSA tests might not be of crucial importance. More importantly, PSA uptake varies considerably between counties. What possible effect this may have on the incidence of metastatic disease and on the prostate cancer specific mortality is yet unknown. Since both the ERSPC and the Göteborg screening trials have shown a reduction in the prostate cancer specific mortality among those men who underwent regular PSA testing,3, 4 it is plausible that high PSA uptake counties have a lower prostate cancer specific mortality compared to low PSA uptake counties. However previous studies on a population-based level comparing areas with high versus low uptake of PSA testing have shown disparate results regarding the effect on prostate cancer mortality.5-7
The concordance between the results from the two models utilized, additive and multiplicative, is the most important strength of the study. Since an assumption was made that the changes in prostate cancer incidence were due to PSA testing, both models were insensitive for influences from other factors. The interpretation of the cumulated number as the proportion of men who ever had a PSA test involves further assumptions. In the trial used for the calculations, men were PSA tested every second year and we made an assumption that men underwent PSA testing only once, although an unknown proportion of men propably underwent multiple PSA testing. Furthermore a high proportion of men with elevated PSA levels in the Göteborg screening trial underwent further follow-up with core biopsies,1 and it is unlikely that an equally high proportion of men in the population with elevated PSA levels underwent further follow-up with core biopsies. In that scenario the actual cumulated uptake of PSA testing would be even higher than the calculated estimations.
References:
- Hugosson J, Aus G, Lilja H, Lodding P, Pihl CG. Results of a randomized, population-based study of biennial screening using serum prostate-specific antigen measurement to detect prostate carcinoma. Cancer 2004;100(7):1397-405.
- Andriole GL, Crawford ED, Grubb RL, 3rd, Buys SS, Chia D, Church TR, et al. Mortality results from a randomized prostate-cancer screening trial. N Engl J Med 2009;360(13):1310-9.
- Schroder FH, Hugosson J, Roobol MJ, Tammela TL, Ciatto S, Nelen V, et al. Screening and prostate-cancer mortality in a randomized European study. N Engl J Med 2009;360(13):1320-8.
- Hugosson J, Carlsson S, Aus G, Bergdahl S, Khatami A, Lodding P, et al. Mortality results from the Goteborg randomised population-based prostate-cancer screening trial. Lancet Oncol 2010;11(8):725-32.
- Lu-Yao G, Albertsen PC, Stanford JL, Stukel TA, Walker-Corkery ES, Barry MJ. Natural experiment examining impact of aggressive screening and treatment on prostate cancer mortality in two fixed cohorts from Seattle area and Connecticut. BMJ 2002;325(7367):740.
- Lu-Yao G, Albertsen PC, Stanford JL, Stukel TA, Walker-Corkery E, Barry MJ. Screening, treatment, and prostate cancer mortality in the Seattle area and Connecticut: fifteen-year follow-up. J Gen Intern Med 2008;23(11):1809-14.
- Bartsch G, Horninger W, Klocker H, Pelzer A, Bektic J, Oberaigner W, et al. Tyrol Prostate Cancer Demonstration Project: early detection, treatment, outcome, incidence and mortality. BJU Int 2008;101(7):809-16.
Written by:
Håkan Jonsson, Benny Holmström, Stephen W. Duffy, and Pär Stattin as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.
Uptake of prostate-specific antigen testing for early prostate cancer detection in Sweden - Abstract
UroToday.com Prostate Cancer Section