Keeping updated on important new findings in diagnostics and therapy of the respective disease is essential for all physicians to provide their patients with high standard medical care. The guidelines of international organizations, such as the EAU are an essential tool in this respect. Evidence-based therapy recommendations should reduce personal bias and improve the success of treatment.
However, several studies have shown that adherence to guidelines by physicians in all specialties is still lacking to a significant extent. A recent study from The Netherlands highlighted this problem by comparing treatment regimens recommended by their national oncologic guidelines with treatment regimens patients received for tumor therapy, showing variances in adherence from 40 to 99%, depending on the tumor entity . However, it is difficult to identify a single cause. Instead, the variance in compliance shows that there must be essential disease-specific differences. To our knowledge, only three retrospective studies exist so far comparing guideline recommendations and actual treatment regimens for local tumor treatment in PeCa [8, 9, 11]. Compliance ranged between 66 and 74.8%. In our survey guideline adherence was dependent on the local tumor stage. For PeCa Tis 80.4%, Ta-T1a 87.3% and T1b 59.1% of the participants chose a procedure that was within the guideline recommendations. Despite great adherence for low local tumor stage (Tis-T1a), only 42.4% of all participants were able to choose a correct treatment approach in all tumor stages. Furthermore, 7.6% did not choose any correct therapeutic approach at all. Of course, it should be noted that the survey results may not reflect "real-life scenarios". Choosing a therapeutic approach in a survey is usually handled with less care than if it was for a real patient. Likewise, in daily practice, key decisions on therapeutic regimens are usually made by or are at least evaluated by an experienced physician. Our survey however involved physicians from different countries and different hospitals, with a broad variance in experience and medical education. This gives us a unique opportunity to determine the main factors that lead to higher compliance with the guidelines.
The Hospitals PeCa Caseload Predicts Guideline Compliance
An important predictor for correct local tumor therapy is the number of PeCa patients treated at a hospital per year. Physicians working at a clinic with a higher frequency of PeCa patients suggested a guideline-based therapy more often. Our results further support the conclusions of previous authors who consider the centralization of medical care as the main key for better care of PeCa patients (1214 [12–14]). Bayles et al. compared the surgical results and the therapeutic success of patients at a single hospital before and after it became a regional reference center for PeCa. Bundling of patients resulted in a significantly higher rate of organ-preserving surgery, especially in patients with advanced local tumor stages . However, it remains questionable whether the increase in organ-preserving interventions detected in this study can be solely attributed to the rise in patient frequency. The control group studied by Bayles et al. before the introduction of centralized medical care consists of patients who underwent surgery between 1969 and 1990. At that time, it was common practice to have a safety distance of at least 2 cm when resecting PeCa. Only after the examined hospital became a regional center for PeCa were studies able to prove that safety margins of only a few millimeters result in an equally good local result, making it the new standard of care . Without this knowledge, organ-preserving surgery could never have been established. Thus, it is difficult to differentiate between the contributions to the improvement of local therapy made by the centralization of medical care and the findings on the surgical safety margin. In contrast to the absolute number of PeCa patients, the size of the clinic (assessed by the number of inpatient beds and medical staff) had just as little influence on guideline adherence as its level of care (primary care hospital, secondary care hospital, maximum-care hospital) or its academic status (university hospital: yes or no). These findings further underline that in such a rare disease as PeCa, regular exposure is of utmost importance and cannot be compensated by structural improvements alone.
Availability of Penile-Sparing Surgery Predicts Great Guideline Compliance
In addition to the number of patients with PeCa treated at a clinic per year, the surgical armamentarium offered also has a high predictive value. Physicians working in a hospital providing penile-sparing surgery were more likely to adhere to the guidelines for their treatment decisions. The availability of penile-sparing surgery is particularly important for local tumor stage T1b. While there are various other less invasive therapeutic options for local tumor stages Tis-T1a, such as laser or topical therapy, radiotherapy is the only less invasive therapeutic alternative to tumor stage T1b . However, none of the participating physicians recommended local radiotherapy for tumor stages Ta-T1b. Therefore, it is not surprising that the possibility of being able to carry out local radiotherapy at the same clinic did not influence guideline adherence at all. In our survey, 33.7% recommended a treatment regime for tumor stage T1b that did not comply with the guidelines. In the majority of cases a too radical surgical method—in this case partial penectomy (31.7% of 33.7%)—was chosen. In contrast, only 1.9% chose a too superficial procedure, laser therapy (0.6%) or resurfacing of the glans 1.3%. This is in line with the findings of Bada et al. and Cindolo et al. who also showed that physicians are more likely to choose a too radical rather than a too superficial surgical approach, a problem that is aggravated in less experienced centers [11, 15]. On a positive note, > 90% of the physicians that participated in our survey stated that penile-sparing surgery is common practice in their department.
The Physicians' Skills Predict Guideline Compliance
Not only differences between the hospitals but also differences among the treating physicians have a great influence on correct tumor treatment. The treating physicians' level of medical education is an essential predictor for correct local tumor treatment. Thus, specialists are more likely to recommend a treatment approach that complies with the guidelines than residents. Curiously, this does not apply to the physicians' surgical skills as the ability to perform surgery on the penis autonomously was not a predictor for correct local tumor treatment. Why the latter does not influence the correct tumor therapy is difficult to explain, because it must be assumed that the group of specialists and the group of experienced surgeons are largely similar. However, this result underlines the importance of clinical experience in the management of oncologic patients in a surgical discipline like urology.
Nonetheless, it is not only clinical experience but also the use of supporting materials in the decision-making process that helps physicians to choose the correct treatment, and this is therefore an essential predictor for guideline compliance; 23.3% of the participants stated that they had used any additional source of reference to answer the questionnaire. Which kind of resource had been used was not specified. However, it is very likely that national or international guidelines, or at least the hospitals' standardized treatment plans, were used to answer the questions. As this has led to an improvement in therapy recommendations, it may be concluded that they are easy to understand and practical to implement. Moreover, a low level of evidence in the guidelines' recommendations, as is the case for penile cancer, does not deter physicians from following them. This indicates that physicians acknowledge that guidelines represent the best evidence available and are willing to accept their recommendations regardless of the significance of the data they are based on. This shows impressively that it is only possible to improve patient care by proving the effectiveness of therapy concepts with high-quality studies. Hence, these kinds of studies are missing for penile cancer, and their initiation has to be further promoted.
This study has several limitations. First, it does not reflect real-life data. In clinical practice treatment decisions are not made based on guideline recommendations alone; they are made depending on the state of health of the patient, his therapy wishes and the treating physicians' personal experience. Of course, they represent the best evidence available, but "guidelines are not mandates and do not purport to be a legal standard of care" . However, due to the small number of cases, it is particularly difficult to develop great expertise in dealing with PeCa patients. The median number of patients treated for PeCa in the participating centers in 2017 was as low as 5 (IQR 3–8). Consequently, the guidelines are of particular importance in the management of these patients. As we know from previous retrospective studies, the contrary position of the treating physician is one of the main reasons that treatment regimens do not follow the guidelines . This in turn explains the strength of our study. It deals exclusively with the physicians’ treatment decisions. Other confounders also influencing treatment decisions in everyday life are faded out. In this way, we were able to identify four parameters that predict the physicians’ guideline compliance for local treatment of PeCa. It is hoped that observance of these principles (1: treatment of patients in high volume centers; 2: penile-sparing surgery is offered by the treating hospital; 3: experienced physicians are involved in the primary therapy decision; 4: in case of any doubt, a source of reference is used) in everyday life will lead to a better rate of guideline-based therapy recommendations and therefore will promote the therapeutic outcome of PeCa patients, especially for patients with a local tumor stage cT1b, who require a less invasive therapy, such as penile-sparing surgery, for the best possible functional result.