Epidemiology of Prostate Cancer

In the USA and worldwide, prostate cancer is the most commonly diagnosed non-dermatologic cancer in men and remains the second most common cause of cancer death in men in the developed world. In a lifetime, prostate cancer will affect approximately 1 in 5 American men [1].

America and Eastern Europe. The lowest incidence rates were reported from South-Central Asia. Absolute numbers in thousands; ASR (W): age standardised rate per 100,000 by world standard Table 1. Absolute numbers and age-standardised rates of incidence and mortality for selected regions and countries [1] Despite its high proportion of cancer diagnoses, prostate cancer is the cause of cancer specific death in only every 16 th case (258 thousand deaths, 6.1% of the total). This places prostate cancer on the sixth position of cancer-specific causes of death, topped by lung, liver, stomach, colorectal and oesophageal cancer. These deaths occur almost equally in both, more developed and less developed regions, thus leading to a twofold higher mortality rate in the more developed regions. Table 2 shows the current incidence and mortality of the USA [2], Germany [7,8] and the Munich Cancer Registry [4]. These rates have changed considerably over time. Time series of more developed countries show that the incidence rates experience a drastic rise from 1985 to 1995 and remain at this high level. In the USA incidence (by world standard per 100,000) increases slowly from 1975 until 1985 (from 50 to 65). Then it rises rapidly reaching a peak of 135 in 1992. Then it decreased, since 1995 more slowly, but it remains on a higher level than before the peak (around 110). In Germany incidence is rising continuously since 1988 (from 30 to 75). The main explanation for these trends is the broad use of prostate specific antigen (PSA) testing as a screening method and performing biopsies, which started in the mid-1980s in the USA and in the early 1990s in Germany. In the USA, mortality initially increases slightly from 1975 and since 1992 it is decreasing more rapidly (from 14 over 17 to 10). In Germany the mortality rate (by world standard per 100,000) stays stable at 13.

Age distribution and age-specific incidence and mortality rate
Nearly all patients (≈ 99%) who are diagnosed with prostate cancer have reached an age of fifty or higher. The age distribution at diagnosis describes a positively skewed unimodal distribution with its modus at the age group 65-69. This age group contributes to nearly 25% of all prostate cancer cases. The risk of getting prostate cancer increases nearly exponentially with increasing age. This makes prostate cancer one of the most distinctive cancers in aging populations ( Figure 1) with a ASIR of 800-1000 per 100,000 in the elderly of 70 years and older.  Figure 1. Age distribution at diagnosis and age-specific incidence rate (ASIR) of prostate cancer (1998-2008) [4] Nearly all patients who died of prostate cancer (singular initial malignoma) have reached an age of fifty-five or higher. The distribution of age at death describes a negatively skewed unimodal distribution with its modus at the highest age group 85+. Here the age-specific mortality rates (ASMR) can perfectly be described by an exponential function. The risk of dying by prostate cancer increases accelerated with increasing age (Figure 2). The ASMR reaches 450 per 100,000 for men with an age of 80-84 and already 600 per 100,000 for men older than 84.

Prognostic factors
According to Table 3 the conditional age distributions of the combined T categories 2 until 4 have the same shape and the modus at the age group of 65 until 69. These distributions are shifted slightly towards higher ages with the increasing T category. This simply reflects that it takes time to develop an advanced tumour. However, in those patients diagnosed with T1 category (clinically) the age distribution appears to be totally different. Here 80% of the men are older than 64 (about 60% within the other T categories) and every third man is older than 74.
Lymph node category (N), distant primary metastases (M), Gleason Score, initial PSA value and Gleason Score are positively correlated with the combined T category: the higher the T category, the higher the PSA value, the higher the Gleason Score and the higher the porportion of regional or distant metastases.
A positive lymph node status is mostly diagnosed when the tumour has spread through the prostatic capsule. Nearly 20% of those men with T3 and almost 50% with T4 tumours therefore are diagnosed with lymph node metastasis. Presented numbers are column-wise percentages.
T category is a combination of cT and pT.
The disease cohort is limited to 2005-2009 to provide best current estimators. About 50% of the men with prostate cancer have a PSA value of 4 to 10 ng/ml at initial diagnosis.
According to Figure 3aa shift from capsule exceeding tumours to capsule limited tumours took place in the 1990s. In the late 1980s about 15% of the diagnosed tumours were staged T4, some 45% T3 and nearly 25% T2. In the 2000s only some 5% of the diagnosed tumours were staged T4, good 20% T3 and about 60% T2. The T1 category was unaffected and oscillated around 12% during the whole time period. It seems that PSA-Screening has considerably lowered the proportion of locally advanced tumours.  Presented numbers are column-wise percentages.

Therapy
T category is a combination of cT and pT.
The disease cohort is limited to 2005-2009 to provide best current estimators.
RPE: radical prostatectomy, TUR: transurethral resection of the prostate, HIFU: high-intensity focused ultrasound, XRT: radiation therapy, Hormone: hormone therapy, AS: active surveillance, WW: watchful waiting Table 4. Initial therapy by T category [4] As Figure 4 shows impressively, initial therapy strategies have changed noticeably over the last 20 years. In the late 1980's radical prostatectomy was the initial therapy in about 25% of all treatments. Its rate increased continuously and finally reaches almost 60%, making this the most selected initial therapy per year since 1995. The curve of hormone therapy developed oppositely. To be more precise: hormone therapy was the most selected treatment till 1994. From 65% in 1989 it continuously decreased to now 20%. Radiation therapy (XRT) slightly increased to 10% as initial therapy. Finally, within the whole time span transurethral resection of the prostate (TUR) remains stable at a proportion of nearly 10%.

Survival
The following figures mainly present the relative survival (RS) curves, an estimator for the cancer specific survival. This is calculated by dividing the overall survival (OS) of the observed cohort by the expected survival of a normal population with the same distribution regarding birth-date and sex.
When looking at the influence of the year of diagnosis on the overall survival ( Figure 5 Figure 8 presents the relative survival by the combined T category. As expected, patients with a T2-staging perform better than patients with a T1-Staging. The 5-and 10-year relative survival is 102.0% and 94.0% in T1, 104.9% and 108.8% in T2, 97.6% and 89.5% in T3 and 61.4% and 43.8% in T4, respectively. Relative survival can exceed 100%, because prostate cancer patients benefit from the better treatment of comorbidities during aftercare. Lymph node status (N category) is an important prognostic factor. As Figure 9 shows, a positive lymph node status (N+) reduces the relative survival drastically (77.7% for 5-year and 61.9% for 10-year survival) compared to a 5-and 10-year survival of 105.5% and 107.5% in N0. Nonetheless, prostate cancer patients benefit from radical prostatectomy in the situation with lymph node metastases [10].     According to Figure 10 patients with the worst Gleason Score category (8 -10) have a much poorer survival (73.4% for five year and 55.0% for ten year survival) than patients with a scoring of 7 and better, which does not discriminate very much (104.1% and 94.8% for Gleason Score 2 -4, 102.2% and 98.6% for Gleason Score 5 -6 and 98.6% and 91.8% for Gleason Score 7).
If the tumour has metastasised or locoregional recurrence has occurred, only 18.2% of the patients survive 5 years and 7.2% of the patients survive 10 years. The median survival is about two years ( Figure 11).