PROMS use validated questionnaires and are therefore standard tools in clinical studies in oncology. They might record different symptoms such as pain, tiredness, nausea, depression, anxiety, drowsiness, loss of appetite, diminishing of well-being, shortness of breath [1] or, other more complex aspects of QoL, such as physical, role, emotional, social and cognitive functioning (https://qol.eortc.org) that are evaluated by the EORTC QLQ C-30. The questionnaires that claim to capture the QoL as a whole, such as the EORTC QLQ C-30, have been developed to compare different therapies in treatment studies and not to depict health complaints or individual preferences for and expectations from a therapy.
There has been a change in patient characteristics over the last decade: the age of patients with newly diagnosed cancer is constantly increasing and, as a consequence, we have more patients with co-morbidities and co-medication, which increases the need of individualized therapies [13, 15, 16]. More and more, advances in medicine have enabled such individually tailored therapies in oncology offering patients different medications with different side effects. In this context, the individual evaluation of complaints and expectations are warranted [5]. Life expectations, and consequently expectations from cancer therapies, are also different between younger and older people [16, 18, 19]. While the assessment of QoL as a whole is undoubtedly important in oncology, the individual weighting of the different aspects of QoL should also be recorded and taken into consideration with the aim of harmonizing the therapy goal with the patient's expectations ("shared decision making") - this applies, in particular, in palliative oncology.
Only one questionnaire used in clinical studies, namely the Memorial Symptom Assessment Scale (MSAS), includes additional questions to find out whether the symptom with pronounced intensity is also important for the patient. The MSAS evaluates the overall prevalence, intensity, and frequency of about 33 different symptoms and, in addition, the distress associated with a particular symptom. The original questionnaire was developed in 1994 and a short version was released in 2020 [18, 19]. Although the MSAS is quite suitable for evaluating therapy- or disease-related symptoms, it does not cover all aspects of QoL as the EORTC QLQ C-30 does. However, such assessments as carried out by MSAS are necessary for shared decision making in which the life situation and expectations regarding QoL of the individual patient are taken into account.
In view of the fact that cancer patients included in our study were in a palliative radiation therapy scheme with the aim of improved QoL (Table 1), we wanted to find out if the scores estimated by the original EORTC QLQ C-30 questionnaire would be different if the distress scale (“How would you currently rate your < functional scale > on a scale from 1 to 5”) were added to it. We found that the differences were striking, as has been shown in the results section. There were differences in 86 % (72/95) of the answers, 39% (37/95) of the answers being more positive and 47 % (45/95) were more negative when subjective weighting was added to items of the EORTC QoL questionnaire (Table 3, Fig. 1). Interestingly, the discrepancies differed considerably between the various functioning scales (Table 4). Whereas the proportion of responses showing no change to the standardized evaluation was low in all scales (11–27%), in most scales, except for physical functioning and role functioning, there was an equal distribution between a more positive and negative rating. The exceptions were the role functioning scale, where the majority (74%) of patients gave a more positive answer and the physical functioning scale, where the majority of patients (53%) gave a more negative answer (Table 4).
We have no doubt that the EORTC QLQ C-30 is a powerful instrument to evaluate the individual life quality at a given time point. This has been shown in numerous studies since its development in 1987 [6]. Nevertheless, whenever improving or maintaining QoL is the primary goal in cancer treatment, the addition of individual interpretation of the different scales evaluated by the questionnaire is necessary, because QoL is a heterogeneous and highly individual construct. The results of our study show that there is a remarkable difference between the classical neutral and impersonal interpretation of the questions and the balanced interpretation that includes the weighting of symptoms by the patients themselves. Interestingly, some of the weighting was more positive, and some more negative as shown in the results. Addition of a weighting question such as “how do you experience your current situation regarding < the function > on a scale from 1 to 5” to the established and reliable EORTC QLQ C-30 questionnaire would, we believe, enable a more individualized cancer therapy in the context of shared decision making in oncology.
We found that the differences were especially high in the interpretation of "role functioning" and, to a less extent, of "emotional functioning". This might be due to the limitations of the study, these being the heterogeneous study group and the higher age of the patients, but the results are nevertheless noteworthy. Other dimensions such as "physical functioning" and "cognitive functioning" are easier to objectify and not so much subject to individual interpretation, which might be one possible explanation for smaller differences in these areas. Also, the limited number of possible answers (1 to 5) for each item in the weighting questions might have influenced the degree of deviation between the answers.
We and others think that one of the advantages of using weighting tools such as the question "does it bother you" should be used to improve therapy monitoring and to prevent therapy-associated problems. This is especially true when the responses are directly reported back to the treating doctor. Our small and limited study might serve as an inspiration to investigate the question in a larger patient group.