Quality Measurement for Soft Tissue Sarcomas in Germany: First Results of the Certified Sarcoma Centres Free

Sarcomas comprise a multitude of different tumour subtypes and are deemed rare cancers [1]. About 70% of all sarcomas are soft tissue sarcomas (STSs) with an incidence of 4,300 cases in 2018 in Germany [1, 2]. About 22% are gastrointestinal stromal tumours (GISTs) and about 9% bone sarcomas [2]. STS requires differentiated interdisciplinary expertise in terms of diagnosis and treatment [3‒5]. Treatment in accordance with clinical guidelines can most likely be expected in specialized centres and has been shown to be a strong independent prognostic factor for progression-free survival as well as overall survival in patients with STS [4, 5]. A recently published study on survival differences between patients treated in a DKG-certified centre or outside showed survival advantages for all 11 tumour types considered (not including sarcomas) [6]. However, a high level of standardization and centralization for STS was lacking in Germany until a few years ago. This distinguished Germany from other countries like France or Denmark [3, 7]. In 2018, an S3 guideline for STS and a certification system for sarcoma centres (including GISTs and bone sarcoma) were initiated by the German Cancer Society (DKG), the German Interdisciplinary Sarcoma Group (GISG), and leading German sarcoma experts. This article presents the first results about the status of patient care in certified sarcoma centres.

Works on the S3 guideline for STS in adults [8] and the certification system began in parallel. The guideline group published a set of quality indicators (QIs) as part of the guideline by a standardized multistep approach established by the German Guideline Programme in Oncology (GGPO) [9]:

• At first, strong recommendations (grade of recommendation A) were selected from the guideline. If they had sufficient relevance for sarcoma care, numerators and denominators were defined (if possible).

• A systematic literature review of English and German QIs was conducted in 2020, using a combination of Medical Subject Headings and free text terms. English and German articles of the last 10 years were searched in PubMed and Cochrane databases as well as Websites of national and international agencies with a focus on quality assurance, quality measurement, and/or QIs. Finally, a Google search was added [10]. All identified national and international QIs [7, 11, 12, 13] were matched to the contents of the strong guideline recommendations in order to get hints on further aspects that could potentially be addressed in a future guideline update.

• After preselection in a first meeting and a written assessment, the final QI set was consented. All these steps are based on standardized exclusion criteria (see Table 1). For the admission of a QI, at least 75% of the QI group members had to vote for the fulfilment of all criteria of a potential QI.

In the context of the established certification system for cancer centres [14], a certification module for sarcoma centres was initiated and successfully piloted in 2018. It was decided to integrate sarcoma centres in so-called oncology centres. Oncology centres, consisting of several tumour-specific certified cancer centres and an overaching joint organizational structure, offer a broad spectrum of oncological expertise, thus enabling an interdisciplinary cooperation with other specialized disciplines such as gynaecology, gastroenterology, and others. The catalogue of requirements (“Erhebungsbogen”) [14, 15] and a first set of indicators (data sheet [DS] [14, 16], see Table 2) for said sarcoma centres were jointly developed and brought to consensus in a multidisciplinary certification commission for sarcoma centres. Commission participants comprised representatives of all medical stakeholders in sarcoma care, including but not limited to surgery, radio-oncology, medical oncology, specialized radiology, nursing, pathology, and patient advocates [15]. Verification of presented structural, procedural, and treatment data is at the core of the annual audit process by sarcoma experts on site who underwent additional training for the auditing process. These audits include inspection of the departments cooperating in the network of the sarcoma centre and review of patient pathways, SOPs, and patient files [14].

Since 2021, the aggregated anonymized results complied from the centres’ DSs are presented in annual reports [17]. These data were used to analyse the centres’ indicator results of 2018–2020. Furthermore, the synthesis of the initial indicator set and the guideline-derived QIs which will be collected as one indicator set from 2021 will be introduced.

As proposed by international consensus statements and treatment guidelines [18], the DKG certification system for sarcoma centres strongly focuses on multidisciplinary cooperation in the framework of specialized treatment networks. Core partners within the network represent surgical disciplines (visceral, thoracic, tumour orthopaedic, and reconstructive surgery), medical oncology, pathology, radiology, and radio-oncology. In addition, a variety of cooperating clinical partners are required for the sarcoma centre, including departments of psycho-social care, human genetics, nuclear medicine among others [15]. Quantitative expertise within the network is mainly ensured through a minimum case number of 50 sarcoma patients (in all stages of disease) treated as well as a minimum amount of 50 tumour resections per year [15].

Data from the certified centres from 2018 to 2020 (see Table 2) give an overview over the centres’ performance. The first 3 years of data show the following main results:

• All centres fulfil the case volume targets (see indicator 1c), the targets for the psycho-oncological counselling rates (indicator 4), and the study quota (indicator 6).

• Developments in pretherapeutic and postoperative tumour board rates (see indicators 2 and 3, respectively) are encouraging and show an improvement over the years. In a similar way, R0 rates for non-GIST STS and bone sarcoma (indicator 7) improved over time.

• Only a minority of the sarcoma centres meets the target for preoperative or postoperative radiotherapy for operated high-risk STS without GIST (indicator 9), while median and fulfilment rates for neoadjuvant therapy for locally advanced STS without GIST (indicator 8) declined over time – although starting high. According to the centres, the reasons were individual decisions of the patients, inconsistent evidence base, impact of the corona pandemic [17].

• Indicator 11 (risk-adjusted adjuvant therapy for GIST) has very few patients in the denominator, so ranges for the rates of the centres are comparatively wide. Some centres (2020: 5 out of 12) had not even 1 patient in the denominator.

• The rates for counselling social service (indicator 5) and pretherapeutic histological confirmation (indicator 10) are stable, although with potential for improvement.

In 2020, median results for ten out of twelve indicators were within the target values or the plausibility limits (2019: 8/12; 2018: 9/12).

The final set of 14 guideline QIs (see Table 3) consists of 13 guideline recommendation-derived QIs and one QI identified by the literature search (postoperative mortality in retroperitoneal sarcoma [RPS] [12]). The set was presented to the sarcoma certification commission in 2021 (shortly after publishing the guideline):

• Two guideline QIs were admitted to the sarcoma DS:

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    QI 10 (pretherapeutic presentation in the tumour board [recurrence and/or secondary distant metastasis of STS]) as a new indicator and

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    QI 11 (postoperative presentation to the tumour board [local recurrence and R1/R2 resection of STS]) by enhancing the denominator of indicator 3 to “total case number with resection”

• One guideline QI was admitted to the DS of gynaecological cancer centres (QI 8: “hysterectomy without morcellement for sarcoma confined to the uterus”).

• Six guideline QIs were not considered necessary for admission because of identical or similar existing indicators in the DS. This applies to

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    QI 1 (pretherapeutic presentation in the tumour board [initial diagnosis of STS]) (see indicator 2)

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    QI 6 (primary histological confirmation of STS) (see indicator 10)

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    QI 7 (R0 resection for STS) (see indicator 7)

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    QI 9 (pre-/postoperative radiotherapy for STS) (see indicator 9)

QI 4 (risk assessment GIST) and QI 5 (mutation analysis GIST) were considered covered in content by the existing indicator 11 (risk-adjusted adjuvant therapy for GIST).

• Five guideline QIs were not admitted to the sarcoma DS for the following reasons:

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    The contents of QI 3 and QI 13 (complete report of findings after resection of STS and GIST, respectively) are already defined in the catalogue of requirements for pathology.

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    The admission of QI 2 (treatment in the certified sarcoma centre) would provide no further information as every patient taking part in the data management is treated in a certified sarcoma centre. While this QI would be more useful if the whole population of sarcoma patients (e.g., of a country or region) was included, this is not the case for certified structures.

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    The definition of the numerator of QI 12 (first-line chemotherapy for STS) was not considered standard for every type of sarcoma and, moreover, was regarded too “small.”

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    QI 14 (postoperative mortality in RPS) was declined by the commission because of the expected low patient numbers in the denominator and consequently a low information value.

Although all guideline QIs were defined for STS and/or GIST, the commission decided or confirmed for the following indicators based on guideline QIs to be suitable also for bone sarcoma:

• QI 1 (pretherapeutic tumour board [initial diagnosis])

• QI 6 (primary histological confirmation)

• QI 7 (R0 resection)

• QI 10 (pretherapeutic tumour board [recurrence and/or secondary distant metastasis])

• QI 11 (postoperative tumour board)

These indicators are established across all or many other DKG certification systems and have proven to be of cross-system significance. Data collection for the additional QIs started in 2022. First results will be available in 2024.

The presented results are unique for sarcomas in Germany. Based on the available data for the first 3 years of the certification system (2018–2020), it can be determined that many relevant quality aspects in sarcoma care are fulfilled from the beginning on. The following points require a further consideration:

• Over the years, more patients were treated in certified sarcoma centres. This is mainly due to a rising number of centres (2018: 7 centres, 2020: 12 centres). Median case numbers increased slightly (2018: 130; 2019: 147.5; 2020: 140), while the case numbers of all centres increased by 90% in the period from 2018 (1,211 cases) to 2020 (2,307 cases) despite the COVID pandemic (see Table 2). But we will need the analyses from the following years to confirm if and how certification leads to centralization (like in France, e.g. [3]). A considerable and rising share of sarcoma patients is now covered by the data.

• The R0 resection rate in sarcoma surgery is influenced by histological subtype and localization. For example, RPS has a median size at presentation often exceeding 20 cm and R0 resection cannot be examined according to the criteria established for sarcoma of the extremities. It is almost impossible to examine the margins of a resection specimen with a surface of more than half a square meter. Therefore, the adequacy of assessing the margins by the pathologist for R0 versus R1 is to some extent dependent from the surgeon indicating and marking the areas of risk for incomplete resection [19]. Also surgery for well-differentiated (grading 1) liposarcomas of the extremities is frequently performed as marginal resection for their relative low biological aggressiveness and the possibility of a re-resection in case of recurrences developing over years in most cases. The same aspect holds true in certain sarcoma subtypes to be resected with marginal margins after preoperative radiation therapy [20].

• Indicators for psycho-oncological care and counselling social services (indicators 4 and 5) can be justified by their high relevance for sarcoma patients. In the case of psycho-oncological care, the results of the centres are quite similar to those of the PROSa study that analysed psycho-oncological care for STS patients in 39 German hospitals [21].

• Indicator 6 (share of study patients) stands not only for a strategy to encourage centres to participate in studies. For metastatic STS patients, the METASARC study showed higher overall and 5-year survival rates for clinical trial participants (odds ratio = 1.59; 95% CI: 1.04–2.42) [22].

• The low fulfilment rates for preoperative or postoperative radiotherapy for operated high-risk STS without GIST (indicator 9) could be cause to differentiate the indicator: preoperative radiotherapy of retroperitoneal STS cannot be considered as standard [23] which may have influenced the results. A differentiation in preoperative and postoperative radiotherapy may be helpful as postoperative radiation may have been performed externally or postoperative wound infections may have played a role.

The DKG certification system as a tumour-specific quality assurance scheme is unique in including tumour-specific QIs, which are commonly derived from evidence-based treatment guidelines. For sarcoma, the harmonization with guideline-derived QIs (see Table 3) by the certification commission was made in a second step. However, it can be determined that many relevant quality measures had already been implemented in the first “expert consent” version of the DS. In the coming years, the extended DS and a larger number of sarcoma centres (18 centres on October 25, 2022) will provide more information on sarcoma care in Germany. Some limitations of these findings are to be considered:

• Although the QIs take into account various tumour characteristics such as tumour stage, the DKG data management does not yet perform a systematic risk adjustment on an individual case level. If a centre fails the target of a specific indicator, it is required to give reasons and to discuss the corresponding results in the audit. That means that there is a “qualitative risk adjustment” for individual cases or centres but not in a systematic way by differentiating according to all relevant factors, e.g., comorbidities.

• Only a minority of German sarcoma patients is documented in the certification system so far. In 2020, there were 1,417 primary cases (including bone sarcoma and GIST) compared to 4,300 incidences of STS cases in Germany [1]. However, certification systems need a certain time to establish. We also hope that increasing knowledge about the advantages of treatment in certified centres [4, 5] will promote further centralization.

• As the collected data bases on a voluntary certification, only a minority of sarcoma patients can be considered and a comparison to patients treated outside of the certified structures is not yet possible. In this respect, our evaluation does not come close to the scope of foreign databases like those in France [24], Denmark [7], or Scotland [12]. We hope that comparisons to patients outside of specialized centres (as already carried out in the Netherlands [11]) will be possible in a few years when clinical cancer registries are more established in Germany.

Adding bone sarcoma indicators will be a future challenge due to the rarity of this cancer type. As a first approach, indicators in the DS that are also established in other certification systems (e.g., pretherapeutic tumour boards) are considered also appropriate for bone sarcoma but cannot substitute an evidence-based guideline as presented in the case of the S3 STS guideline [10]. Developing the certification system for sarcoma presents an opportunity to gather experiences with those centres treating bone sarcoma and could provide clues and ideas for modifying the DS. Thus, through the above-described example, the constantly evolving and adapting characteristics of the DKG certification system are well illustrated.

We would like to thank the members of the QI working group and the certification commission for the trustworthy and professional cooperation during the last years.

Ethical approval is not required for this study in accordance with local or national guidelines.

Johannes Rückher, Ellen Grießhammer, Thomas Langer, Gregor Wenzel, Martin Utzig, and Simone Wesselmann are employees of the German Cancer Society. Peter Hohenberger was a member of the Guideline Commission S3 Guideline Adult Soft Tissue Sarcomas and is the representative of the Interdisciplinary Working Group Soft Tissue Sarcoma (IAWS) of the German Cancer Society. Lars H Lindner received travel support from Dr. Sennewald Medizintechnik, PharmaMar, and honoraria from Novartis, Lilly, Eisai, EL Medconsult, Boehringer Ingelheim, Deciphera, and GSK.

Jens Jakob was a member of the Guideline Commission S3 Guideline Adult Soft Tissue Sarcomas and is the representative of the German Society for General and Visceral Surgery in the Certification Commission for Sarcoma Centres. He received expense allowances and travel allowances from Lilly, Belpharma, and PharmaMar for lectures and advisory boards on sarcoma but not related to the guideline or QIs.

No funds were received from any sources for this work.

Johannes Rückher: conceptualization, formal analysis, and writing – original draft. Ellen Grießhammer, Thomas Langer, Gregor Wenzel, and Martin Utzig: review and editing. Peter Hohenberger, Lars H Lindner, Jens Jakob, and Simone Wesselmann: conceptualization and review and editing.

The datasets of 2019 and 2020 analysed in the article are publicly available at https://www.krebsgesellschaft.de/jahresberichte.html. The datasets of 2018 are not available because of the small number of centres at the time and the resulting potential identifiability. Further enquiries can be directed to the corresponding author.