Survival of prostate cancer patients in central and northern Denmark, 1998-2009

Five-Year Survival is Not a Useful Measure for Cancer Control in the Population: an Analysis Based on UK Data

Background:

Five-year survival is an important metric for progress in cancer control broadly used both in the cancer literature and by the public. In order to assess its validity and relation to other common metrics, we analyzed the relationship between 5-year survival, incidence and mortality using publicly available cancer registry data from England and Wales.

Methods:

Five-year survival, incidence and mortality data were obtained from the online database of a registered charity, Cancer Research UK. We extracted sex-specific age-standardized mortality, incidence, and 5-year survivalfor16 types of cancer over the period from 1976 to 1995. The relationships between 5-year survival, incidence and mortality were estimated using both Pearson and Spearman correlation coefficients.

Results:

All 16cancer types showed an increase in 5-year survival for both genders from 1976 to 1995, ranging from 0.2% (pancreas and lung cancer) to 16.6% (prostate cancer) for males and 0.2% (pancreas cancer) to 16.6% (leukemia) for females. From 1976 to 1995, there was no significant correlation between changes in 5-year survival and cancer mortality for either sex (males, Pearson r=0.16, Spearman r=-0.06; females, Pearson r=-0.33, Spearman r=-0.43). A positive relationship between 5-year survival and incidence was noted among males, but not among females (males, Pearson r=0.61, Spearman r=0.53; females, Pearson r=0.03, Spearman r=0.11). However, after excluding breast and prostate cancer, the positive association became weaker and became statistically non-significant for males (Pearson r=0.47; Spearman r=0.41).

Conclusions:

Our findings suggest that there are no reliable relationships between changes in 5-year survival and cancer incidence or mortality. Increases in 5-year survival might therefore represent poor indicators of progress in cancer control at the population level. In the absence of over-diagnosis, 5-year survival might only indicate improved diagnosis and treatment in clinical practice.

Circulating biomarkers to monitor cancer progression and treatment

Tumor heterogeneity is a major challenge and the root cause of resistance to treatment. Still, the standard diagnostic approach relies on the analysis of a single tumor sample from a local or metastatic site that is obtained at a given time point. Due to intratumoral heterogeneity and selection of subpopulations in diverse lesions this will provide only a limited characterization of the makeup of the disease. On the other hand, recent developments of nucleic acid sequence analysis allows to use minimally invasive serial blood samples to assess the mutational status and altered gene expression patterns for real time monitoring in individual patients. Here, we focus on cell-free circulating tumor-specific mutant DNA and RNA (including mRNA and non-coding RNA), as well as current limitations and challenges associated with circulating nucleic acids biomarkers.

Does comorbidity interact with prostate cancer to increase mortality? A Danish cohort study of 45 326 prostate cancer patients diagnosed during 1995-2011

BACKGROUND

Many prostate cancer patients die of other causes, but it remains unknown whether comorbidity interacts synergistically with prostate cancer to increase the mortality rate beyond that explained by the individual risks of comorbidity and prostate cancer.

METHODS

A nationwide cohort study of 45 326 Danish prostate cancer patients diagnosed during 1995-2011, each matched to approximately five men from the general population on age and individual comorbidities in the Charlson Comorbidity Index (CCI). We calculated five-year mortality rates and interaction contrasts as a measure of the excess mortality rate explained by synergy between prostate cancer and comorbidity.

RESULTS

Five-year mortality was 46.8% in prostate cancer patients and 25.8% in matched men from the general population. For prostate cancer patients with a CCI score of 2-3, the mortality rate was 250 per 1000 person-years [95% confidence interval (CI): 236, 263], and interaction between comorbidity and prostate cancer accounted for 20% of the total mortality rate (50 deaths per 1000 person-years, 95% CI 35, 65) in the first year following cancer diagnosis. The interaction was mainly present for patients with metastatic disease and those not treated with prostatectomy.

CONCLUSION

Up to 20% of all deaths among men who had both prostate cancer and comorbidities could be explained by the comorbidity-prostate cancer interaction. The mortality attributable to comorbidity itself and the mortality attributable to the interaction may be reduced by successful treatment of the comorbidity.

Survival and PSA-markers for mortality and metastasis in nonmetastatic prostate cancer treated with androgen deprivation therapy

BACKGROUND

Few studies have examined the risk of developing castration-resistant prostate cancer (CRPC), metastasis, and mortality among nonmetastatic prostate cancer (M0-PC) patients treated with androgen deprivation therapy (ADT). We estimated the incidence of these outcomes among M0-PC patients on ADT and identified prostate-specific antigen (PSA) based biomarkers for mortality and metastasis.

METHODS

This population-based cohort study included all nonmetastatic prostate cancer patients in Northern and Central Denmark Regions during 1997-2010, identified through registry data. Primary outcomes were metastasis, overall survival, and bone metastasis-free survival (BMFS). We estimated relative risks (RR) associated with PSA and PSA doubling-time (PSA-DT), measured as time-varying variables beginning at ADT treatment start.

RESULTS

We included 2494 M0-PC patients treated with ADT, of whom 1617 (80%) developed CRPC during follow-up. One-fourth of the patients developed metastases within 5 years; bone metastases (BM) accounted for 81% of all metastases. Median survival time was 4.4 years. Compared with PSA <8 ng/mL, PSA ≥8 ng/mL was associated with an adjusted RR of 14.0 (95% confidence interval [CI]: 10.2, 19.0) for BM, 4.4 (CI: 3.9, 5.0) for all-cause mortality, and RR of 4.8 (CI: 4.3, 5.4) for the inverse of BMFS. PSA-DT ≤6 months was associated with an adjusted RR of 7.6 (95% CI: 6.1, 9.5) for BM, RR of 5.9 (CI: 5.2, 6.6) for all-cause mortality, and RR 6.6 (CI: 5.9, 7.4) for the inverse of BMFS.

CONCLUSIONS

PSA ≥8 ng/mL and PSA-DT ≤6 months are strong predictors of mortality and bone metastasis. The poor prognosis observed in this study may reflect inclusion of patients with severe prostate cancer by requiring repeated PSA measurements.

Danish General Practitioners' Use of Prostate-Specific Antigen in Opportunistic Screening for Prostate Cancer: A Survey Comprising 174 GPs

Background. The use of prostate-specific antigen test has markedly increased in Danish general practice in the last decade. Despite the national guidelines advice against PSA screening, opportunistic screening is supposed to be the primary reason for this increased number of PSA tests performed. Aims. Based on the increase in the amount of PSA conducted, we aimed to analyse how GPs in Denmark use the PSA test. Methods. A self-administrated questionnaire concerning symptomatic and asymptomatic patient cases was developed based on the national and international guidelines and the extensive literature review, and an in-depth interview conducted with a GP was performed. Results. None of the GPs would do a PSA measurement for an asymptomatic 76-year-old man. For asymptomatic 55- and 42-year-old men, respectively, 21.9% and 18.6% of GPs would measure PSA. Patient request and concern could be potential reasons for measuring PSA for asymptomatic patients. Almost all GPs stated that a PSA measurement is indicated for symptomatic 49- and 78-year-old men, respectively, 98.9% and 93.8%. Conclusion. Opportunistic PC screening is being performed in general practice to a high degree. Hence, current guidelines are not followed, and intense focus should be on more effective implementation strategies in order to avoid overuse of PSA.

Comorbidity and survival of Danish prostate cancer patients from 2000-2011: a population-based cohort study

Objective

We investigated temporal changes in overall survival among prostate cancer (PC) patients and the impact of comorbidity on all-cause mortality.

Methods

We conducted a population-based cohort study in the Central Denmark Region (1.2 million inhabitants). Using medical registries, we identified 7,654 PC patients with first-time PC diagnosis within the period 2000–2011 and their corresponding comorbidities within 10 years prior to the PC diagnosis. We estimated 1- and 5-year survival in four consecutive calendar periods using a hybrid analysis and plotted Kaplan–Meier survival curves. We used Cox proportional hazards regression to compute 1- and 5-year age-adjusted mortality rate ratios (MRRs) for different comorbidity levels. All estimates are reported with their corresponding 95% confidence intervals (CI).

Results

The annual number of PC cases doubled over the 12-year study period. Men aged <70 years accounted for the largest proportional increase (from 33% to 47%). The proportion of patients within each comorbidity category remained constant over time. One-year survival increased from 82% (CI: 80%–84%) in 2000–2002 to 92% (CI: 90%–93%) in 2009–2011, while 5-year survival increased from 43% (CI: 40%–46%) to 65% (CI: 62%–67%) during the same time intervals. Improvements in 5-year survival were most prominent among patients aged <80 years and among those with no comorbidity (from 51% to 73%) and medium comorbidity (from 32% to 54%). Improvements in survival were much smaller for those with high comorbidity (from 33% to 39%). The 1-year age-adjusted MRR for patients with high comorbidity (relative to patients with no comorbidity) increased over time from 1.84 (CI: 1.19–2.84) to 3.67 (CI: 2.49–5.41), while the 5-year age-adjusted MRR increased from 1.73 (CI: 1.34–2.23) to 2.38 (CI: 1.93–2.94).

Conclusion

Overall survival of PC improved substantially during 2000–2011, although primarily among men with low comorbidity. All-cause mortality was highest among PC patients with high comorbidity, and their relative 1- and 5-year mortality increased over time compared to those without comorbidity.

Methods and rationale used in a matched cohort study of the incidence of new primary cancers following prostate cancer

Objectives

We describe several methodological issues that were addressed in conducting a Danish population-based matched cohort study comparing rates of new primary cancers (NPCs) in men with and without prostate cancer (PC).

Methods

We matched 30,220 men with PC to 151,100 men without PC (comparators) on age (±2 years) and PC diagnosis/index date. We focused on several methodological issues: 1) to address survival differences between the cohorts we compared rates with and without censoring comparators on the date their matched PC patient died or was censored; 2) to address diagnostic bias, we excluded men with a history of cancer from the comparator cohort; 3) to address prostate cancer immunity, we graphed the hazard of NPC in both cohorts, with and without prostate cancer as an outcome; 4) we used empirical Bayes methods to explore the effect of adjusting for multiple comparisons.

Results

After 18 months of follow-up, cumulative person-time was lower in the PC than comparator cohort due to higher mortality among PC patients. Terminating person-time in comparators at the matched PC patient’s death or loss to follow-up resulted in comparable person-time up to 30 months of follow-up and lower person-time among comparators thereafter. The hazard of NPC was lower among men with PC than comparators throughout follow-up. There was little difference in rates beyond the first four years of follow-up after removing PC as an outcome. Empirical Bayes adjustment for multiple comparisons had little effect on the estimates.

Conclusion

Addressing the issues of competing risks, treatment interference or diagnostic bias, prostate cancer immunity due to radical prostatectomy, and multiple comparisons lowered the deficit rate of NPCs among men with a history of PC compared with those without PC. However, the differing rates of NPCs may also be due to risk factor differences between the cohorts.

Socio-economic inequalities in survival of patients with prostate cancer: role of age and Gleason grade at diagnosis

In the United Kingdom, survival of prostate cancer patients has improved since the 1990s. A deprivation gap in survival (better survival for the least deprived compared with the most deprived) has been reported but it is not known if differential distribution of earlier age or lower grade disease at diagnosis might explain such patterns. We therefore investigated the impact of age and Gleason grade at diagnosis on the deprivation gap in survival of prostate cancer patients over time. Incident cases of prostate cancer (ICD-10 C61) from the West of Scotland were extracted from the Scottish Cancer Registry from 1991 to 2007. Socio-economic circumstances were measured using the Scottish Index for Multiple Deprivation 2004 (SIMD). Age and deprivation specific mortality rates were obtained from the General Registrar Office for Scotland (GRO(S)). The survival gradient across the five deprivation categories was estimated with linear regression, weighted by the variance of the relative survival estimate. We examined the data for 15,292 adults diagnosed with prostate cancer between 1991 and 2007. Despite substantial improvements in survival of prostate cancer patients, a deprivation gap persists throughout the three periods of diagnoses. The deprivation gap in five year relative survival widened from −4.76 in 1991–1996 to −10.08 in 2003–2007. On age and grade-specific analyses, a significant deprivation gap in five year survival existed between all age groups except among patients' age ≥75 and both low and high grade disease. On multivariate analyses, deprivation was significantly associated with increased excess risk of death (RER 1.48, 95% CI 1.31–1.68, p-value<0.001) independent of age, Gleason grade and period of diagnosis. The deprivation gap in survival from prostate cancer cannot be wholly explained by socio-economic differentials in early detection of disease. Further research is needed to understand whether differences in comorbidities or treatment explain inequalities in prostate cancer outcomes.