In this study, guideline adherence and implementation of tumor board recommendations for gastrointestinal cancer patients at a certified, tertiary referral academic oncological cancer center in Germany was assessed over a time-period of one year in each single presented case. To the best of our knowledge, this is the first study to investigate adherence to the German cancer treatment guidelines for patients with gastrointestinal tumors. To determine guideline adherence, we compared the given treatment recommendations of each MTB case with the associated guideline recommendations and categorized their adherence into complete adherence in 76%, minor deviations in 9%, and major deviations in 7% of all selected MTB cases. Previous studies determined guideline adherence based on NCCN guidelines and, in contrast to our study, by examining adherence to specific guideline recommendations among tumor therapies received (Bagante et al. 2019; Hamad et al. 2021; Jaap et al. 2018; Visser et al. 2012; Worhunsky et al. 2015; Zhao et al. 2018). In these studies, guideline adherence was only differentiated dichotomously into complete and non-adherence, designing a wide range. These studies likewise investigated patient- and tumor-specific factors associated with guideline deviations. Analogous to our results, these included higher comorbidity scores, higher tumor stage, and specific tumor entities (Chagpar et al. 2012; Hamad et al. 2021; Hines et al. 2015; Nishida et al. 2020). Compared to these other studies, our results showed no dependence of guideline adherence on patient age (Bagante et al. 2019; Boland et al. 2013; Chagpar et al. 2012; Hines et al. 2015; Kimmick et al. 2014; Nishida et al. 2020; Schiphorst et al. 2014; Visser et al. 2012; Worhunsky et al. 2015). Nevertheless, none of the studies has investigated, whether these patient and tumor factors were the actual reasons of guideline deviations (Hamad et al. 2021; Hines et al. 2015; Thiels et al. 2020). In our study, the most common cause of guideline deviation was the inclusion of patients into clinical trials. In accordance with the research focus of the UCCL, patients with gastric and esophageal cancer were often recommended therapies in the context of clinical trials, therefore our study design resulted in many minor guideline deviations in these patients. Although tumor boards generally increase patients’ access to clinical trials (Kuroki et al. 2010; Mobley et al. 2020), these results may not be representative for MTBs of other hospitals.
Concerning the treatment implementation rate of 64% in our study, we compared our results with two previous studies investigating the tumor board adherence of gastrointestinal cancer patients. Tumor board adherence of colorectal carcinoma patients was studied by Wood et al. (2008), whereas Balzeby et al.(2006) focused on patients with tumors of the upper gastrointestinal tract. Both studies used a dichotomous, but not uniform or transparent definition of tumor board adherence, showing deviation rates of 10 and 15%. However, the specific causes of tumor board deviations were collected and both studies were consistent with our results, in which comorbidities, patient preferences, and tumor factors (e.g. increase in the extent of tumor disease, possible mutation detection, response to therapy) were identified as the most common reasons for deviating from tumor board recommendations.
In our analysis, comorbidities of cancer patients were one of the main influencing factors on guideline and tumor board adherence. 24% of guideline deviations were due to patient comorbidity status, and lower guideline adherence was significantly associated with an ECOG-PS ≥ 2 (p < .05). In accordance with the literature, it becomes clear that patients with higher comorbidity scores are less likely to be considered in guideline development, and, therefore, less likely to receive guideline-concordant treatment (Barth et al. 2016; Francke et al. 2008; Hahn et al. 2018; Stairmand et al. 2015; Vinod 2015). In medicine, guideline recommendations for patients with comorbidities are usually based on weak to moderate evidence or are not available at all (Lugtenberg et al. 2011). One of the reasons for this is the frequent exclusion of these patients from randomized controlled trials defining the new standards of care in oncology (Sedrak et al. 2021; Townsley et al. 2005). Lack of information regarding patients’ comorbidities or preferences and wishes also occurs in tumor board meetings (Abukar et al. 2018; Bolle et al. 2019; Lamb et al. 2013; Wihl et al. 2021). In our study, patient comorbidities caused 24% of tumor board deviations and an ECOG-PS ≥ 2 was significantly associated with lower tumor board adherence (p < .05). Currently, there is neither a gold standard for comorbidity measurement in oncological patients nor a standard regarding patient-specific data that is required to make robust treatment recommendations in tumor boards (Sarfati 2012; Wihl et al. 2021). Further, this may prevent MTB participants from making treatment decisions and from fully implementing them (Blazeby et al. 2006; Jalil et al. 2013; Wood et al. 2008).
Higher adherence rates could possibly be achieved by asking patients for specific treatment preferences before the MTB meeting takes place (Hollunder et al. 2018; Solomon et al. 2003). In our study, 16% of deviations from tumor board recommendations were due to divergent patient preferences. However, the perfect timing for consulting patients and asking for their preferences remains unclear. Especially considering that patient preferences might change during the course of treatment (Mallinger et al. 2006).
Limitations of our study were the implementation as a single center study, focusing on gastrointestinal tumors alone, the newly implemented methodology for patient selection and adherence definition and the limited patient number. Therefore, further validation of our methodology and results are warranted. However, a major advantage of our study design is the individual patient-centered approach in combination with a systematic and objective quality assessment tool. Rather than examining the implementation of individual guideline recommendations in a cohort of patients, we looked at each individual case discussion to see whether evidence-based guideline recommendations were, first, available and, second, recommended by the respective MTB meetings. On this way we simultaneously subjected the guidelines to a review of the extent to which they are applicable in the local oncological setting. In this context the present study design allowed us to detect 6.4% of tumor board cases for which no specific guideline recommendations were available, especially by focusing not only on primary cases but all treatment lines. Therefore, our study could also contribute to new approaches of quality assurance for certified cancer centers.