2. Introduction – Colorectal Cancer

Colorectal cancer (CRC) is one of the most common malignant tumors in Germany with over 64.000 newly-diagnosed cases and about 26,000 deaths per year. For the first time in 1999, the DGVS in cooperation with the German Cancer Society published an S3 guideline for CRC, which was intended to provide an exhaustive, standardized, high- value set of patient care guidelines based on evidence-based medicine. In the meantime, a European colorectal cancer guideline has also been published. The guideline committee felt specifications are necessary, because of the heterogeneous health care systems and care standards in the European countries. This German guideline covers additional aspects that are not covered by the European guideline. It strives to consider all issues relevant for Germany.

The guideline is divided into eight topic complexes (TC):

• TC I: Prevention Asymptomatic Population (see Chapter 3)
• TC II: Screening Asymptomatic Population (see Chapter 4)
• TC III: Risk Groups (see Chapter 5)
• TC IV: Endoscopy: Implementation and Management of Polyps (see Chapter 6)
• TCV: PreoperativeDiagnosticsandSurgery(seeChapter7)
• TC VI: Adjuvant and Neoadjuvant Therapy (see Chapter 8)
• TC VII: Management of Patients with Metastases and in the Palliative Situation (see Chapter 9)
• TC VIII: Follow-up Care (see Chapter 10)

In order to keep these recommendations at the most current stage of scientific knowledge, the guideline has since been regularly updated in close cooperation with the AWMF (2004 completely, 2008 the TC IV, VI, and VII and 2011/2012 the topic complexes I, II, III, V und VIII as well as parts of IV, VI and VII). The current update concerns the topic complexes IV, VI and VII.

During the update process in 2017, the guideline group decided that recommendations would be made on the following issues:

• When should a surveillance colonoscopy be performed after removal of a sessile serrated adenoma?
• When should a surveillance colonoscopy be performed after removal of 1 or 2 adenomas < 1 cm without high grade intraepithelial neoplasia?
• Up to which time interval after surgery of a colon cancer should an adjuvant chemotherapy be performed?
• Which rectal cancer patient should receive neoadjuvant treatment?
• Is there an indication for adjuvant chemotherapy after neoadjuvant treatment of rectal cacer?
• What is the benefit of adjuvant treatment after R0-resection of liver metastases?
• What is the benefit of a combination therapy with an EGFR-antibody or VEGF-pathway Inhibitor in the firstline-therapy?

Based on these questions, all recommendations were reviewed whether they were up-to-date. If necessary, they were updated after literature searches.

The S3-Leitlinie is valid until the next update. The validity is approximately 5 years. Intended are regular updates of the whole guideline, in case of urgent need of change individual recommendations/topics can be revised.

In the recommendation boxes the date of the last update are listed (2008, 2013 or 2017).

Comments and suggestions for the update are explicitly welcome and can be addressed to the guideline secretariat.

Guideline coordination: PD Dr. Christian P. Pox Guideline secretariat

Medizinische Klinik der Ruhr-Universität Bochum Knappschaftskrankenhaus

In der Schornau 23-25

D-44892 Bochum

meduni-kkh@rub.de

The methodology of the guideline programme oncology asks - according to the AWMF- rules – for the allocation of a grade of recommendation by the guideline authors in the context of a formal consensus process. Accordingly moderated nominal group processes as well as structured consensus conferences took place [1]. As part of this process a formal vote was taken on the recommendations by all mandate holders. The result of each vote (degree of consensus) is categorized according to Table 4 for each recommendation.

For all evidence-based statements (see Chapter 2.3.3) and recommendations, the evidence level (see Chapter 2.3.1) of the underlying studies as well as for recommendations the degree of recommendation (Grades of Recommendation) are shown. Three degrees of recommendation are distinguished in this guideline (see Table 4) which also reflect the formulation of the recommendations.

The drafting and update of the guideline was performed independently of the funding organization, the German cancer aid (Deutsche Krebshilfe). The mandate holders and experts are to be thanked for their voluntary work without which the formulation of the S3-guideline would not have been possible.

All members of the guideline group gave a written statement concerning possible conflicts of interest. These can be found in the guideline report (http://www.leitlinienprogramm-onkologie.de/leitlinien/kolorektales-karzinom/).

The relevance of the conflicts of interest for the guideline was discussed in several meetings (kick-off meeting and consensus conference) and by email. In the update 2010- 2013 (Version 1) the conflicts of interest were reviewed and evaluated by the coordinators. For the update 2015-2017 (Version 2) Prof. Kolligs the authorized conflict of interest representative performed the review and evaluation of the disclosed conflicts of interest.

As proposed by Prof. Kolligs the guideline group decided that there would be no restrictions for any delegate in the voting process as inappropriate distortion of guideline recommendations was considered highly unlikely. The reason for this was the methodological approach as well as the multidisciplinary composition of the guideline group.

During the update 2010-2013 Prof. Schmiegel abstained from voting on FOBT/iFOBT, genetic stool tests and M2-PK because of a possible conflict of interest.

The risk of interference by conflicts of interest was also reduced by engaging independent external institutes for literature search, selection and assessment for politically sensitive topics. The formal consensus process and interdisciplinary drafting of the guideline are additional instruments to minimize interference by industry.