Risk of dying from prostate cancer in men randomized to screening: differences between attendees and nonattendees

13 C NMR quantification of polyamine syntheses in rat prostate

Currently, many prostate cancer patients, detected through the prostate specific antigen test, harbor organ-confined indolent disease that cannot be differentiated from aggressive cancer according to clinically and pathologically known measures. Spermine has been considered as an endogenous inhibitor for prostate-confined cancer growth and its expression has shown correlation with prostate cancer growth rates. If established clinically, measurements of spermine bio-synthesis rates in prostates may predict prostate cancer growth and patient outcomes. Using rat models, we tested the feasibility of quantifying spermine bio-synthesis rates with ¹³ C NMR. Male Copenhagen rats (10 weeks, n = 6) were injected with uniformly ¹³ C-labeled L-ornithine HCl, and were sacrificed in pairs at 10, 30, and 60 min after injection. Another two rats were injected with saline and sacrificed at 30 min as controls. Prostates were harvested and extracted with perchloric acid and the neutralized solutions were examined by ¹³ C NMR at 600 MHz. ¹³ C NMR revealed measurable ornithine, as well as putrescine-spermidine-spermine syntheses in rat prostates, allowing polyamine bio-synthetic and ornithine bio-catabolic rates to be calculated. Our study demonstrated the feasibility of ¹³ C NMR for measuring bio-synthesis rates of ornithine to spermine enzymatic reactions in rat prostates. The current study established a foundation upon which future investigations of protocols that differentiate prostate cancer growth rates according to the measure of ornithine to spermine bio-synthetic rates may be developed.

Racial and ethnic differences in risk of second primary cancers among prostate cancer survivors

PURPOSE

Previous studies have shown an overall decreased risk of second cancers among prostate cancer survivors, but this has not been comprehensively examined by race/ethnicity. We conducted a retrospective cohort study of 716,319 one-year survivors of prostate cancer diagnosed at ages 35-84 during 2000-2015 as reported to 17 US Surveillance, Epidemiology and End Results (SEER) registries.

METHODS

We estimated standardized incidence ratios (SIRs) for second primary non-prostate malignancies by race/ethnicity (non-Latino white, Black, Asian/Pacific Islander [API] and Latino), by Gleason, and by time since prostate cancer diagnosis. Poisson regression models were used to test heterogeneity between groups with the expected number as the offset.

RESULTS

60,707 second primary malignancies were observed. SIRs for all second cancers combined varied significantly by race/ethnicity: SIR_white: 0.88 (95% confidence interval: 0.87-0.89), SIR_Latino: 0.92 (0.89-0.95), SIR_Black: 0.97 (0.95-0.99), and SIR_API: 1.05 (1.01-1.09) (p-heterogeneity < 0.001). SIRs for all cancers combined were higher among survivors of higher vs. lower Gleason prostate cancers irrespective of race/ethnicity. We observed significant heterogeneity by race/ethnicity in SIRs for 9 of 14 second cancer types investigated including lung, bladder, kidney, and liver.

CONCLUSIONS

Our results confirm that most prostate cancer survivors have lower risks of second cancers than expected, but the magnitude varied by race/ethnicity. Exceptionally, API men had small but significantly increased risk. Further research to understand drivers of the observed race/ethnicity heterogeneity is warranted.

Metabolomic Prediction of Human Prostate Cancer Aggressiveness: Magnetic Resonance Spectroscopy of Histologically Benign Tissue

Prostate cancer alters cellular metabolism through events potentially preceding cancer morphological formation. Magnetic resonance spectroscopy (MRS)-based metabolomics of histologically-benign tissues from cancerous prostates can predict disease aggressiveness, offering clinically-translatable prognostic information. This retrospective study of 185 patients (2002-2009) included prostate tissues from prostatectomies (n = 365), benign prostatic hyperplasia (BPH) (n = 15), and biopsy cores from cancer-negative patients (n = 14). Tissues were measured with high resolution magic angle spinning (HRMAS) MRS, followed by quantitative histology using the Prognostic Grade Group (PGG) system. Metabolic profiles, measured solely from 338 of 365 histologically-benign tissues from cancerous prostates and divided into training-testing cohorts, could identify tumor grade and stage, and predict recurrence. Specifically, metabolic profiles: (1) show elevated myo-inositol, an endogenous tumor suppressor and potential mechanistic therapy target, in patients with highly-aggressive cancer, (2) identify a patient sub-group with less aggressive prostate cancer to avoid overtreatment if analysed at biopsy; and (3) subdivide the clinicopathologically indivisible PGG2 group into two distinct Kaplan-Meier recurrence groups, thereby identifying patients more at-risk for recurrence. Such findings, achievable by biopsy or prostatectomy tissue measurement, could inform treatment strategies. Metabolomics information can help transform a morphology-based diagnostic system by invoking cancer biology to improve evaluation of histologically-benign tissues in cancer environments.

[PSA screening 2013: background and perspectives]

In the healthcare political discussions on treatment measures, the controversy over prostate-specific antigen (PSA) screening has taken a leading role in comparison to, for example the relatively undisputed role of breast and colon screening. This has fortunately led to an in-depth critical analysis of the available data. One advantage is the benefit on survival which increases with longer follow-up observation times. When carrying out studies the quantitative extent of this benefit can become obscured by prescreening, prevalent screening, lack of compliance, contamination and healthy screen bias. Nevertheless, the European randomized screening study of prostate cancer (ERSPC) study, for example, showed sufficient statistical power to confirm a screening benefit after 9 or 11 years (evidence level A). However, even for prostate cancer the internal problems of preventive medicine of overdiagnosis and overtherapy are also partially dependent on the age range of the screening population and the screening frequency (28-52%). Unnecessary deficits in the quality of life reduce the benefit of survival in these patients. By using a PSA fine tuning and risk stratification, approximately one third of diagnoses and therapies can be avoided. Additionally, the active surveillance of tumors unsuitable for treatment together with an improved quality of therapy should become of greater importance.

The Finnish prostate cancer screening trial: analyses on the screening failures

Prostate cancer (PC) screening with prostate-specific antigen (PSA) has been shown to decrease PC mortality in the European Randomized Study of Screening for Prostate Cancer (ERSPC). However, in the Finnish trial, which is the largest component of the ERSPC, no statistically significant mortality reduction was observed. We investigated which had the largest impact on PC deaths in the screening arm: non-participation, interval cancers or PSA threshold. The screening (SA) and control (CA) arms comprised altogether 80,144 men. Men in the SA were screened at four-year intervals and referred to biopsy if the PSA concentration was ≥ 4.0 ng/ml, or 3.0-3.99 ng/ml with a free/total PSA ratio ≤ 16%. The median follow-up was 15.0 years. A counterfactual exclusion method was applied to estimate the effect of three subgroups in the SA: the non-participants, the screen-negative men with PSA ≥ 3.0 ng/ml and a subsequent PC diagnosis, and the men with interval PCs. The absolute risk of PC death was 0.76% in the SA and 0.85% in the CA; the observed hazard ratio (HR) was 0.89 (95% confidence interval (CI) 0.76-1.04). After correcting for non-attendance, the HR was 0.78 (0.64-0.96); predicted effect for a hypothetical PSA threshold of 3.0 ng/ml the HR was 0.88 (0.74-1.04) and after eliminating the effect of interval cancers the HR was 0.88 (0.74-1.04). Non-participating men in the SA had a high risk of PC death and a large impact on PC mortality. A hypothetical lower PSA threshold and elimination of interval cancers would have had a less pronounced effect on the screening impact.

A different method of evaluation of the ERSPC trial confirms that prostate-specific antigen testing has a significant impact on prostate cancer mortality

The advantages and disadvantages of two different methods of analyzing the European Randomized Study of Screening for Prostate Cancer (ERSPC) trial with respect to the effect of prostate-specific antigen (PSA) screening on prostate cancer (PCa) mortality (ie, disease-specific mortality analysis and excess mortality analysis) are discussed in depth. The traditional disease-specific mortality is the best end point, but it could be biased by misclassification of causes of death, and it does not take into account the possible effect of the screening process on other causes of death. Excess mortality analysis overcomes these problems, but the results could be biased if the expected mortality is not corrected for attendance status. Both methods, when applied to the ERSPC trials, demonstrate that no increase in non-PCa mortality occurred in the screening group and confirm that PSA screening decreases PCa mortality.

Early detection of prostate cancer: European Association of Urology recommendation

BACKGROUND

The recommendations and the updated EAU guidelines consider early detection of PCa with the purpose of reducing PCa-related mortality and the development of advanced or metastatic disease.

OBJECTIVE

This paper presents the recommendations of the European Association of Urology (EAU) for early detection of prostate cancer (PCa) in men without evidence of PCa-related symptoms.

EVIDENCE ACQUISITION

The working panel conducted a systematic literature review and meta-analysis of prospective and retrospective clinical studies on baseline prostate-specific antigen (PSA) and early detection of PCa and on PCa screening published between 1990 and 2013 using Cochrane Reviews, Embase, and Medline search strategies.

EVIDENCE SYNTHESIS

The level of evidence and grade of recommendation were analysed according to the principles of evidence-based medicine. The current strategy of the EAU recommends that (1) early detection of PCa reduces PCa-related mortality; (2) early detection of PCa reduces the risk of being diagnosed and developing advanced and metastatic PCa; (3) a baseline serum PSA level should be obtained at 40-45 yr of age; (4) intervals for early detection of PCa should be adapted to the baseline PSA serum concentration; (5) early detection should be offered to men with a life expectancy ≥ 10 yr; and (6) in the future, multivariable clinical risk-prediction tools need to be integrated into the decision-making process.

CONCLUSIONS

A baseline serum PSA should be offered to all men 40-45 yr of age to initiate a risk-adapted follow-up approach with the purpose of reducing PCa mortality and the incidence of advanced and metastatic PCa. In the future, the development and application of multivariable risk-prediction tools will be necessary to prevent over diagnosis and over treatment.

Excess all-cause mortality in the evaluation of a screening trial to account for selective participation

OBJECTIVE

In addition to disease-specific mortality, a randomized controlled cancer screening trial may be evaluated in terms of excess mortality, in which case no patient-specific information on causes of death is needed. We studied the effect of not accounting for attendance on the calculated excess mortality in a prostate cancer screening trial.

METHODS

The numerator of the excess mortality rate related to prostate cancer diagnoses in each study arm equals the excess number of deaths observed in the cancer patients. The estimation of the expected number of deaths in the absence of the prostate cancer diagnoses has to account for the self-selection of those participating in the trial, particularly if the proportion of non-participants is substantial.

SETTING

The European prostate cancer screening trial (ERSPC).

RESULTS

In the screening arm, non-attendees had roughly twice the mortality rate of attendees. Approximately twice as many cancers were detected in the screening arm compared with the control arm, primarily in attendees. Unless attendance is properly accounted for, the expected mortality of prostate cancer patients in the screening arm is overestimated by 0.9-3.6 deaths per 1000 person-years.

CONCLUSIONS

Attendees have a lower all-cause mortality rate (are healthier) and a higher probability of a prostate cancer diagnosis than non-attendees and the men randomized to the control arm. If attendance is not accounted for, the excess mortality and the between-arm excess mortality rate ratio are underestimated and screening is considered more effective than it actually is. These effects may be sizeable, notably if non-attendance is common. Correcting for attendance status is important in the calculation of the excess mortality rate in prostate cancer patients that can be used in conjunction with a disease-specific mortality analysis in a randomized controlled cancer screening trial.

Comorbidity and mortality results from a randomized prostate cancer screening trial

PURPOSE

Estimates of prostate cancer-specific mortality (PCSM) were similar for men randomly assigned to intervention compared with usual care on the Prostate, Lung, Colorectal and Ovarian PC screening study. However, results analyzed by comorbidity strata remain unknown.

PATIENTS AND METHODS

Between 1993 and 2001, of 76,693 men who were randomly assigned to usual care or intervention at 10 US centers, 73,378 (96%) completed a questionnaire that inquired about comorbidity and prostate-specific antigen (PSA) testing before random assignment. Fine and Gray's multivariable analysis was performed to assess whether the randomized screening arm was associated with the risk of PCSM in men with no or minimal versus at least one significant comorbidity, adjusting for age and prerandomization PSA testing.

RESULTS

After 10 years of follow-up, 9,565 deaths occurred, 164 from PC. A significant decrease in the risk of PCSM (22 v 38 deaths; adjusted hazard ratio [AHR], 0.56; 95% CI, 0.33 to 0.95; P = .03) was observed in men with no or minimal comorbidity randomly assigned to intervention versus usual care, and the additional number needed to treat to prevent one PC death at 10 years was five. Among men with at least one significant comorbidity, those randomly assigned to intervention versus usual care did not have a decreased risk of PCSM (62 v 42 deaths; AHR, 1.43; 95% CI, 0.96 to 2.11; P = .08).

CONCLUSION

Selective use of PSA screening for men in good health appears to reduce the risk of PCSM with minimal overtreatment.

Mortality results from the Göteborg randomised population-based prostate-cancer screening trial

BACKGROUND

Prostate cancer is one of the leading causes of death from malignant disease among men in the developed world. One strategy to decrease the risk of death from this disease is screening with prostate-specific antigen (PSA); however, the extent of benefit and harm with such screening is under continuous debate.

METHODS

In December, 1994, 20,000 men born between 1930 and 1944, randomly sampled from the population register, were randomised by computer in a 1:1 ratio to either a screening group invited for PSA testing every 2 years (n=10,000) or to a control group not invited (n=10,000). Men in the screening group were invited up to the upper age limit (median 69, range 67-71 years) and only men with raised PSA concentrations were offered additional tests such as digital rectal examination and prostate biopsies. The primary endpoint was prostate-cancer specific mortality, analysed according to the intention-to-screen principle. The study is ongoing, with men who have not reached the upper age limit invited for PSA testing. This is the first planned report on cumulative prostate-cancer incidence and mortality calculated up to Dec 31, 2008. This study is registered as an International Standard Randomised Controlled Trial ISRCTN54449243.

FINDINGS

In each group, 48 men were excluded from the analysis because of death or emigration before the randomisation date, or prevalent prostate cancer. In men randomised to screening, 7578 (76%) of 9952 attended at least once. During a median follow-up of 14 years, 1138 men in the screening group and 718 in the control group were diagnosed with prostate cancer, resulting in a cumulative prostate-cancer incidence of 12.7% in the screening group and 8.2% in the control group (hazard ratio 1.64; 95% CI 1.50-1.80; p<0.0001). The absolute cumulative risk reduction of death from prostate cancer at 14 years was 0.40% (95% CI 0.17-0.64), from 0.90% in the control group to 0.50% in the screening group. The rate ratio for death from prostate cancer was 0.56 (95% CI 0.39-0.82; p=0.002) in the screening compared with the control group. The rate ratio of death from prostate cancer for attendees compared with the control group was 0.44 (95% CI 0.28-0.68; p=0.0002). Overall, 293 (95% CI 177-799) men needed to be invited for screening and 12 to be diagnosed to prevent one prostate cancer death.

INTERPRETATION

This study shows that prostate cancer mortality was reduced almost by half over 14 years. However, the risk of over-diagnosis is substantial and the number needed to treat is at least as high as in breast-cancer screening programmes. The benefit of prostate-cancer screening compares favourably to other cancer screening programs.

FUNDING

The Swedish Cancer Society, the Swedish Research Council, and the National Cancer Institute.