Teemu J. Murtola

Cholesterol-Lowering Drugs and Prostate Cancer Risk: A Population-based Case-Control Study

Background: Previous studies have shown that statin use may reduce prostate cancer risk. In the current study, we evaluated the association between serum cholesterol–lowering medication use and prostate cancer risk at the population level. Materials and Methods: All newly diagnosed prostate cancer cases in Finland during 1995 to 2002 and matched controls (24,723 case control pairs) were identified from the Finnish Cancer Registry and the Population Register Center, respectively. Detailed information on cholesterol-lowering drug purchases during the study period was obtained from the prescription database of the Social Insurance Institution of Finland. Results: After adjustment for potential confounders, having ever-use of any statin was associated with marginally elevated overall prostate cancer risk [odds ratio (OR), 1.07; 95% confidence interval (95% CI), 1.00-1.16]. However, none of the statins was associated with the overall prostate cancer risk when analyzed separately. On the other hand, the risk of advanced prostate cancer was decreased among users of atorvastatin, lovastatin, and simvastatin (OR 0.61, 95% CI 0.37-0.98; OR 0.61, 95% CI 0.43-0.85; and OR 0.78, 95% CI 0.61-1.01, respectively). The risk was not affected among users of other cholesterol drug groups. Conclusions: Our large population-based study showed no evidence for reduced overall prostate cancer risk among users of cholesterol-lowering drugs, whereas the risk of advanced cancer was decreased among statin users. (Cancer Epidemiol Biomarkers Prev 2007;16(11):2226–32)

Prostate cancer and PSA among statin users in the Finnish prostate cancer screening trial

Decreased risk of advanced prostate cancer has been reported among men using statins. However, the evidence on overall prostate cancer risk is conflicting. We compared the relative risk between current users and non‐users of statins or other cholesterol‐lowering medications in a population undergoing systematical prostate cancer screening. The study cohort comprised of 23,320 men participating in the screening arm of the Finnish prostate cancer screening trial during 1996–2004. Information on medication use was obtained from a comprehensive national prescription database. Cox proportional hazards regression was used to calculate multivariable adjusted hazard ratios (HRs) for prostate cancer. Serum prostate‐specific antigen (PSA) level was compared between current users and non‐users of cholesterol‐lowering drugs. Compared with medication non‐users, the overall prostate cancer incidence was decreased among statin users [HR 0.75, 95% confidence interval (CI) 0.63–0.89]. The inverse association was dose‐dependent with cumulative amount of statin use, and strongest for low‐grade and early stage tumors. The incidence was nonsignificantly lower also among users of other types of cholesterol‐lowering drugs (HR 0.62, 95% CI 0.28–1.38), but without dose‐dependence. Age‐adjusted median serum PSA tended to be lower among users of cholesterol‐lowering drugs, but the relative risk decrease among statin users was not related to decreased PSA. Overall incidence of prostate cancer was lowered among statin users when bias due to differential PSA testing between medication users and non‐users was eliminated by systematical prostate cancer screening. Cholesterol‐lowering with statins seems beneficial for prostate cancer prevention.

Antidiabetic Medication and Prostate Cancer Risk: A Population-based Case-Control Study

Decreased risk of prostate cancer in diabetic men has been reported. The authors evaluated the association between antidiabetic medication use and prostate cancer at the population level. All incident prostate cancer cases in Finland during 1995-2002 were identified from the Finnish Cancer Registry. Matched controls were provided by the Population Register Center (24,723 case-control pairs). Information on medication use was obtained from a comprehensive prescription database. Multivariable-adjusted odds ratios were computed by using conditional logistic regression. The authors found that prostate cancer risk was decreased for antidiabetic medication users (odds ratio = 0.87, 95% confidence interval: 0.82, 0.92). The decrease was observed for most drug groups. The odds ratio decreased in a dose-dependent fashion by quantity of use. Duration of antidiabetic treatment was inversely associated with overall prostate cancer risk and risk of advanced cancer. Similar risk reduction for users of different antidiabetic drugs suggests that diabetes, instead of the medication itself, is behind the association. This finding is unlikely to be secondary because of differential uptake of the prostate-specific antigen test or different prostate-specific antigen levels between medication users and nonusers; prevalence of testing in Finland is low. Dose and time dependency of the relation probably indicates that duration of diabetes is negatively associated with risk.

Statins and prostate cancer prevention: where we are now, and future directions

Statins are cholesterol-lowering drugs that are widely used to prevent and treat atherosclerotic cardiovascular disease. Recent research from both in vitro and in vivo studies suggests that there is an association between the use of statins and a reduction in the incidence of and mortality from prostate cancer. Several mechanisms of action that might bring about these beneficial effects of statins have been proposed, most of which include direct effects of statins on intracellular signaling. In this Review we discuss the current knowledge on the use of statins to prevent prostate cancer. We will also look at future directions for clinical research on this topic.

Use of aspirin, but not other non-steroidal anti-inflammatory drugs is associated with decreased prostate cancer risk at the population level

The cyclooxygenase 2 (COX-2) enzyme overexpression in prostate cancer has led to the hypothesis that COX-2 inhibition may reduce prostate cancer growth. Some previous studies have linked the usage of COX-2 inhibiting non-steroidal anti-inflammatory drugs (NSAIDs) with a decreased prostate cancer risk. We estimated the association between cumulative COX-2 inhibition by NSAID usage and prostate cancer risk at population level. All new prostate cancer cases in Finland during 1995-2002 and matched controls (24,657 case-control pairs) were identified from national registries. Detailed information on medication purchases was obtained from a national prescription database. A total cumulative COX-2 inhibition value was calculated based on total cumulative mg amount of each NSAID drug and the drug-specific COX-1/COX-2 inhibition ratio. Prostate cancer risk was analysed with propensity score-matched conditional logistic regression model. In total, 53.8% of the cases and 46.5% of the controls had any prescription-use of NSAIDs, while 8.1% and 7.9%, respectively, had used aspirin. Compared to the non-users, any NSAID use was associated with an elevated overall prostate cancer risk (46.4% versus 53.6%, respectively; odds ratio [OR] 1.3, 95% confidence interval [CI] 1.3, 1.4) and risk of advanced cancer (11.8% versus 14.1%; OR 1.6, 95% CI 1.5, 1.8). The risk remained elevated despite the amount of cumulative COX-2 inhibition. In a separate analysis, the risk increase was similar for each NSAID with the exception of aspirin, which was associated with a decreased overall prostate cancer risk (OR 0.90, 95% CI 0.84, 0.96) in a dose-dependent fashion. NSAID use is associated with an increased prostate cancer risk at the population level regardless of the COX-2 inhibition. This may be explained by systematic differences between prescription NSAID users and non-users. In contrast, aspirin use is associated with a decreased overall prostate cancer risk. Further studies on aspirin and prostate cancer will be needed.

Statin Use and Breast Cancer Survival: A Nationwide Cohort Study from Finland

Recent studies have suggested that statins, an established drug group in the prevention of cardiovascular mortality, could delay or prevent breast cancer recurrence but the effect on disease-specific mortality remains unclear. We evaluated risk of breast cancer death among statin users in a population-based cohort of breast cancer patients. The study cohort included all newly diagnosed breast cancer patients in Finland during 1995–2003 (31,236 cases), identified from the Finnish Cancer Registry. Information on statin use before and after the diagnosis was obtained from a national prescription database. We used the Cox proportional hazards regression method to estimate mortality among statin users with statin use as time-dependent variable. A total of 4,151 participants had used statins. During the median follow-up of 3.25 years after the diagnosis (range 0.08–9.0 years) 6,011 participants died, of which 3,619 (60.2%) was due to breast cancer. After adjustment for age, tumor characteristics, and treatment selection, both post-diagnostic and pre-diagnostic statin use were associated with lowered risk of breast cancer death (HR 0.46, 95% CI 0.38–0.55 and HR 0.54, 95% CI 0.44–0.67, respectively). The risk decrease by post-diagnostic statin use was likely affected by healthy adherer bias; that is, the greater likelihood of dying cancer patients to discontinue statin use as the association was not clearly dose-dependent and observed already at low-dose/short-term use. The dose- and time-dependence of the survival benefit among pre-diagnostic statin users suggests a possible causal effect that should be evaluated further in a clinical trial testing statins’ effect on survival in breast cancer patients.

The importance of LDL and cholesterol metabolism for prostate epithelial cell growth

Cholesterol-lowering treatment has been suggested to delay progression of prostate cancer by decreasing serum LDL. We studied in vitro the effect of extracellular LDL-cholesterol on the number of prostate epithelial cells and on the expression of key regulators of cholesterol metabolism. Two normal prostatic epithelial cell lines (P96E, P97E), two in vitro immortalized epithelial cell lines (PWR-1E, RWPE-1) and two cancer cell lines (LNCaP and VCaP) were grown in cholesterol-deficient conditions. Cells were treated with 1–50 µg/ml LDL-cholesterol and/or 100 nM simvastatin for seven days. Cell number relative to control was measured with crystal violet staining. Changes in mRNA and protein expression of key effectors in cholesterol metabolism (HMGCR, LDLR, SREBP2 and ABCA1) were measured with RT-PCR and immunoblotting, respectively. LDL increased the relative cell number of prostate cancer cell lines, but reduced the number of normal epithelial cells at high concentrations. Treatment with cholesterol-lowering simvastatin induced up to 90% reduction in relative cell number of normal cell lines but a 15–20% reduction in relative number of cancer cells, an effect accompanied by sharp upregulation of HMGCR and LDLR. These effects were prevented by LDL. Compared to the normal cells, prostate cancer cells showed high expression of cholesterol-producing HMGCR but failed to express the major cholesterol exporter ABCA1. LDL increased relative cell number of cancer cell lines, and these cells were less vulnerable than normal cells to cholesterol-lowering simvastatin treatment. Our study supports the importance of LDL for prostate cancer cells, and suggests that cholesterol metabolism in prostate cancer has been reprogrammed to increased production in order to support rapid cell growth.

Effects of simvastatin, acetylsalicylic acid, and rosiglitazone on proliferation of normal and cancerous prostate epithelial Cells at therapeutic concentrations

Non‐steroidal anti‐inflammatory drugs and cholesterol‐lowering statins have been reported to inhibit prostate cancer cell growth suggesting their chemopreventive potential within the prostate. However, the effect has been demonstrated only with advanced prostate cancer cell lines and with drug concentrations above the clinical therapeutic range. In this study we compared the effect of therapeutic concentrations of acetylsalicylic acid, simvastatin and rosiglitazone on the growth of a set of prostatic primary cultures and various prostate epithelial cell lines.

False-positive screening results in the Finnish prostate cancer screening trial

Background:There is evidence that prostate cancer (PC) screening with prostate-specific antigen (PSA) serum test decreases PC mortality, but screening has adverse effects, such as a high false-positive (FP) rate. We investigated the proportion of FPs in a population-based randomised screening trial in Finland.Methods:Finland is the largest centre in the European Randomized Study of Screening for Prostate Cancer. We have completed three screening rounds with a 4-year screening interval (mean follow-up time 9.2 years) using a PSA cutoff level of 4.0 ng ml−1; in addition, men with PSA 3.0–3.9 and a positive auxiliary test were referred. An FP result was defined as a positive screening result without cancer in biopsy within 1 year from the screening test.Results:The proportion of FP screening results varied from 3.3 to 12.1% per round. Of the screened men, 12.5% had at least one FP during three rounds. The risk of next-round PC following an FP result was 12.3–19.7 vs 1.4–3.7% following a screen-negative result (depending on the screening round), risk ratio 3.6–9.9. More than half of the men with one FP result had another one at a subsequent screen. Men with an FP result were 1.5 to 2.0 times more likely to not participate in subsequent rounds compared with men with a normal screening result (21.6–29.6 vs 14.0–16.7%).Conclusion:An FP result is a common adverse effect of PC screening and affects at least every eighth man screened repeatedly, even when using a relatively high cutoff level. False-positive men constitute a special group that receives unnecessary interventions but may harbour missed cancers. New strategies are needed for risk stratification in PC screening to minimise the proportion of FP men.

Prostate cancer incidence among finasteride and alpha-blocker users in the Finnish Prostate Cancer Screening Trial

Background:The Prostate Cancer Prevention Trial has shown a protective effect of finasteride on prostate cancer in low-risk men. It is uncertain whether similar results can be expected when finasteride is used to treat benign prostatic hyperplasia.Methods:We performed an observational cohort study within the Finnish Prostate Cancer Screening Trial. Using a comprehensive prescription database on medication reimbursements during 1995–2004 of men using finasteride or alpha-blockers for benign prostatic hyperplasia, we evaluated prostate cancer incidence among 23 320 men screened during 1996–2004.Results:Compared to medication non-users, overall prostate cancer incidence was not significantly affected in finasteride users (hazard ratio 0.87; 95% CI 0.63–1.19). Incidence of Gleason 2–6 tumours, however, was decreased among finasteride users (HR 0.59; 95% CI 0.38–0.91), whereas incidence of Gleason 7–10 tumours was unchanged (HR 1.33; 95% CI 0.77–2.30). The protective effect concerned mainly screen-detected tumours. Overall prostate cancer risk was not significantly reduced among alpha-blocker users relative to non-users, but decreased incidence of high-grade tumours was observed (0.55; 95% CI 0.31–0.96).Conclusions:The detection of low-grade, early-stage tumours is decreased among men who use finasteride for symptomatic BPH. The protective effect of finasteride can also be expected in men with benign prostatic hyperplasia.