DISSECTION 2.0

This study is investigating whether removal of the pelvic lymph nodes has an effect on the development of prostate cancer.

The current standard for radical prostatectomy, i.e. the surgical removal of the prostate, is the simultaneous removal of the pelvic lymph nodes if there is an increased risk of cancer metastases in the lymph nodes.

However, it is still unclear whether the removal of the pelvic lymph nodes actually represents an advantage in terms of the course of the disease.

The aim is to gain reliable insights into the possible therapeutic benefit of removing the pelvic lymph nodes at the same time. In addition, the data collected will be used to create models to determine who is most likely to benefit from the procedure.

Participation in the study is voluntary and lasts up to 15 years, similar to cancer aftercare. The study patient must adhere to the schedule and all instructions given by the investigator.

Before participation, various routine examinations are carried out, including possibly a computer tomography (CT), a magnetic resonance tomography (MRT) or a positron emission tomography (PET-CT) of the whole body. In addition, the prostate-specific antigen (PSA value) is determined and a physical examination is carried out.

After inclusion in the study, the patient is randomly assigned to one of two treatment groups.

Standard treatment/control group: A prostatectomy with removal of the pelvic lymph nodes is performed.

Experimental group: Prostate removal without removal of the pelvic lymph nodes.

After the operation, follow-up checks are carried out after 3 months, 6 months, 1 year and then annually until the 10th year and a final check-up after 15 years. A follow-up check is also carried out if a relapse is suspected. This corresponds to the standard follow-up schedule for your cancer.

The PSA value is evaluated, as well as questions to record side effects/complications and quality of life.

The study patient must inform the investigator if their state of health changes, e.g. if they feel worse or if new symptoms occur. This also applies if the patient wishes to terminate the study prematurely.

For the study patient, participation lasts a maximum of 15 years after removal of the prostate. Participation can be terminated earlier at any time. The patient does not have to explain why they no longer wish to participate. Patients who wish to end their participation earlier are asked to speak to the investigator.

Premature termination of participation has no influence on further medical care and treatment. The data and samples collected up to that point (e.g. blood values or x-rays) will still be analyzed for the study. The study data and samples will remain encrypted

The patient is not exposed to any additional risks as a result of the research project.

Nevertheless, every medical treatment is associated with risks and burdens. This can also occur in the context of studies. Since the treatment option we are investigating (not removing the lymph nodes) causes fewer immediate complications compared to standard treatment (removal of the lymph nodes), we do not expect participation in the study to result in any additional direct complications or burdens.

However, it is currently unknown whether not removing the lymph nodes will have a long-term negative impact on the course of your disease.

As only this study will show whether the removal of the pelvic lymph nodes influences the course of the disease, it cannot be predicted whether this is to the benefit or detriment of the patient.

However, depending on the results of the study, the findings could improve the treatment strategy for future patients.

There are results that concern the patient him/herself. Your investigator will inform you of these results.

There are also incidental findings. Incidental findings are "incidental findings" that are not intended. We will inform you if these incidental findings are relevant to your health.

There are also the overall results of the study, which come from the data of all participants. These results do not directly affect you or your health. However, your investigator will be happy to provide you with a summary of the overall results of the study at the end of the study if you wish.

In addition, the results will be published in layman's language after the end of the study.

DISSECTION 2.0 is a multicenter, national study. The University Hospital Basel is the coordinating center.

The following centers in Switzerland are already participating in the study. Further centers will follow.

• University Hospital Basel
• Cantonal Hospital Baselland
• University Hospital Zurich