Adherence to the EAU Guideline Recommendations for Local Tumor Treatment in Penile Cancer: Results of the European PROspective Penile Cancer Study Group Survey (E-PROPS)

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 [12]. 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 [6]. 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.

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 [2]. 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.

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" [2]. 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 [8]. 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.