In this paper, we are reporting on pre-treatment prostate-specific quality of life (QoL) in newly-diagnosed PC patients with a maximum age of 79 years, who were scheduled to receive either RT or RP and in German reference men from the general population.
Differences between German and Canadian study cohorts
As shown in Tables
1,
2,
3,
4, the German reference men and newly-diagnosed PC patients from Germany and Canada differ in some aspects. In the Canadian study more men were still working than in Germany (Table
2) – although Canadian cancer patients were a little older than German patients (Table
1). In Germany, the usual retirement age of men belonging to the birth cohort 1940 is 65 years. But early retirement, usually at 63 years of age, is possible. In Canada, the usual age for retirement is also 65 years, but many retire as early as 60 years of age, while professionals and self-employed people may work after age 65, either full-time or part-time. Differences between the study groups are also found regarding educational attainment (Table
2). In Germany in 2007, 13% of people over age 45 years had at least 10 years of schooling and another 13% had 12 years [
19]. In Canada in 2006, 25% of persons aged 45 to 64 completed high school (12 years of schooling), and 19% had a university degree [
20]. Therefore, the Canadian patients in this study were better educated than the Canadian population and than the German cohorts.
From other studies it is known that besides co-morbidity, education and employment affect QoL ratings [
21,
22]. Because of this and the fact that the two studies were not originally designed for cross-national comparisons, we did not perform statistical tests for differences between QOL scorings of German and Canadian men.
Differences between patients scheduled to receive radiation therapy or radical prostatectomy
As shown, PC patients from Germany and Canada differ in some aspects which may affect QoL. However, differences also were found between patients scheduled to receive RP and RT (e.g. age (Table
1), education (Table
2), and disease stage (Tables
3,
4)). Other studies, too, reported that patients scheduled for RT (or who have received RT) were older than patients scheduled for RP [
23,
24], had higher pre-treatment PSA, higher Gleason scores, and more progressed tumours as indicated by T-stage [
24,
25]. There are two possible reasons for the observed age differences. Older age may be regarded as a risk factor for undesired side effects of surgical procedures, thus RT may be recommended to older men. Secondly, the EAU guideline states that one indication for surgery (RP) is that the expected post-operative survival should be 10 years or more [
4]. With increasing age and associated co-morbidities expected survival decreases, therefore older patients might be more likely to receive RT. Furthermore, tumours in younger patients are often more aggressive, so an early excision of the tumour with surgery is indicated.
We used a prostate-specific tool for assessing QoL: The Patient Oriented Prostate Utility Scale (PORPUS, see additional file
1). This tool is unique in that takes key determinants of QoL such as sexual, urinary and bowel dysfunction into account [
11]. Its acceptability, reliability, and validity [
11,
12,
15,
16] make it a valuable tool not only in study situations. Due to its shortness, the PORPUS-P can be easily integrated into daily routine in urology practices. The paper-and-pencil form can be completed in approximately 3:30 minutes (pilot study with 20 German men; mean age: 48 years (SD: 15 years); 50% had less than 12 years schooling).
Originally, the PORPUS-P was designed for use in PC patients. But its QoL domains are also relevant among men in the general population, as with increasing age erectile dysfunction [
8,
9], urinary incontinence [
10] and bowel problems are common. Our study indicates that approximately 20% of men in the general population and of PC patients who have not yet been treated with RP or RT, of all ages, have problems in these areas. These observed prevalence rates are a little lower than reported for the general population in Canada and Europe [
8‐
10], furthermore Staff et al. reported pre-treatment prevalence rates for ED of 44% in US patients with localized PC, who were scheduled to receive RT. However, impaired bowel function (8%) or impaired urinary function (18%) was less common in their study than in ours [
26]. The authors are only aware of one other study that used PORPUS-P in non-metastatic PC patients and controls. In the study of Joly et al. more PC patients on ADT reported low energy (36%), poor bladder control (47%) and loss of sexual function (95%) than age-matched controls (16%, 34% and 33%, respectively), which could be attributed to the cancer therapy [
27].
Problems in other areas of QoL were also reported by our respondents, notably energy level; only 9% of the apparently healthy men, 13% of the German patients, and 26% of the Canadian patients reported feeling "very full of energy, lots of pep", while 6% of the German RT, 5% of the German RP, 11% of the Canadian RT and 6% of the Canadian RP patients reported having generally low energy or pep (level 4) or having no energy at all (level 5).
Monga et al. showed that 8% of veterans (mean age: 67 years) with localized PC experienced fatigue before treatment [
28] and Joly et al. reported that 14% of non-metastastic PC patients on ADT and 4% of controls experienced severe fatigue [
27]. Schwarz and Hinz assessed QoL with the EORTC QLQ-C30 in the general German population. Of all respondents 10% scored 50 or more points on the fatigue scale (0–100, high scores indicate a high level of symptomatology) [
29].
The Canadian and the German version of PORPUS-P have different response schemes for the item "emotional well being". "Quite a bit of worry, sadness, or frustration" was omitted from the German version, so respondents had only 4 levels for this item (see Figure
2). Interestingly, 49.8% of the German patients but only 40% of the Canadians reported being "generally happy and free from worry, sadness, or frustration" (answer category 1). Conversely, only 9.3% of the German patients reported moderate or extreme worry, sadness, or frustration (level 3 and 5), compared with 23% of the Canadian patients who reported moderate, quite a bit, or extreme worry, sadness, or frustration (level 3–5). We do not think that the observed differences are only due to the different response formats in the Canadian and the German versions of the PORPUS. It is possible that "emotional well being" is a different concept in the studied countries.
Comparing the response patterns in Germany and Canada (Figures
1,
2,
3), there are differences between the Canadian English version, as used in Canadian PC patients, and the German version as used in German men (i.e. emotional well being, sexual function), but many of the answer distributions are similar.
The crude PORPUS-P scores differ significantly between RT and RP patients from Germany (mean scores: 77 vs. 81) and Canada (mean scores: 78 vs. 85), respectively. Focusing on the age-specific strata it appears that, in reference men, mean scores decrease by about 4 points per 10 years. Also Schwarz and Hinz found detriments in QoL in the general German population as age increased [
29]. In German RP patients, mean PORPUS-P scores decrease after age 60. In Canadian RP patients, mean scores decrease by at least 5 points every 10 years, and these patients have the highest mean scores of all 5 groups up to age 64. There is little or no evidence of age-related decreases in the German or Canadian RT patients.
Based on the works of King et al. [
30], Osoba et al. [
31], and Ringash et al. [
32] a difference of five percent of the scale range can indicate a minimal important difference (i.e. clinically relevant difference). Since the PORPUS-P has a 0 to 100 point scale, we assume a difference of 5 points is clinically relevant (but further studies have to validate this assumption). Thus, we see clinically relevant different PORPUS-P scores between German reference men and German RT patients as well as clinically relevant differences between the PORPUS-P scores of RT and RP patients in both countries. Radiotherapy is often given to PC patients with a higher degree of co-morbidity, which might influence QoL ratings more than the (still untreated) tumour. Other studies showed also that RT patients rate their pre-treatment health related QoL lower than RP patients – this effect is more pronounced when disease specific QoL instruments are used than when using generic instruments [
25,
33,
34].
In our studies rates of ADT were quite similar for Canadian and German RT patients (54 vs. 40%) and RP (2 vs. 7%) patients. Hormone therapy is also known to influence QoL [
27] and (as expected) PORPUS-P scorings of all Canadian and of all German patients differed significantly between men with and without ADT. In accordance with our results, Joly et al. [
27] showed that non-metastatic PC patients with at least three months of ADT had significantly lower PORPUS-P scores than healthy age-matched control men (median: 71 vs. 86; p < 0.001).
Missing values
The Canadian data, collected in personal interviews, have no missing data, but the German studies were conducted by mail so there were missing values. It is often assumed that persons are unwilling to answer questions about sexual and urinary function. This assumption is true for our data; 18.1% of the German PC patients had missing data for the item sexual function, 8.7% gave no answer to the item on sexual interest, 6.4% provided no answer regarding urinary leakage, and 5.7% had missing data concerning urinary frequency. In comparison, only 0.3% to 1.7% of the German reference men did not answer these questions.
Furthermore it has been suggested that missing values are more common when problems are present (thus, people are more willing to report the absence of problems) [
35]. Under the assumption that missing values indicate a high level of deterioration, the "true" German values might be overestimated by our study samples and differences in QoL ratings between Canada and Germany might be even more marked than in data presented here. Replacing missing values with the level indicating the most severe problem would result in crude PORPUS-P values of 82.6 for the reference men, 76.2 for RT patients and 79.9 for RP patients. Replacing missing values with the level indicating no problem would reveal mean values of 83.3 for the reference men, 77.5 for RT and 81.2 for RP patients.
Strengths and Limitations
In the present study, we were able to report on three datasets from two countries and conduct a cross-national comparison of men with PC. One of the strengths is the inclusion of nearly 1,000 reference men from the general population, who provided information on prostate specific and general QoL. Unfortunately, it was not possible to give a questionnaire on health status to the reference men, and only 50% of the German PC patients answered a checklist on co-morbidities, while this information is available for patients from Canada. The observed age effect in RP patients may be due to other factors that were not examined in German patients such as co-morbidity. In the Canadian study the Charlson co-morbidity score was computed [
14]. Both age and co-morbidity were significantly correlated with PORPUS-P scores (for age and PORPUS-P, r = -0.386, p < 0.001, and for co-morbidity and PORPUS-P, r = -0.206, p = 0.017). But there was no significant relationship between age and Charlson score (r = 0.082, p = 0.34), which might be due to the inhomogeneous distribution of Charlson scores in the group. Furthermore, it might be possible that due to differing exclusion and inclusion criteria for prostate cancer patients in Germany and Canada both study groups may be heterogeneous in characteristics that we did not measure or report here.
More than any other tumour, PC is a neoplasm of the elderly. For example, in Germany, the mean age at diagnosis is approximately 70 years and more than 90% are aged 60 years or older [
2]. The median age of our German cancer patients was 64 years. In the German studies elderly and very old patients were not allowed to participate due to reasons of remembrance abilities and capacity. In the Canadian study poor cognitive abilities was an exclusion criterion, and the oldest participant was 79 years. As we have observed inverse relationships between age and QoL scoring in all three studies it might be possible that the reported QoL ratings are too optimistic to be generalized to all prostate cancer patients (including the elderly and the very old patients).