The impact of taste and smell alterations in different stages of investigation and treatment of lung cancer

Abstract

Background: Taste and smell are two of our senses, which together with our other senses provide sensory information central to the experience of the flavours of what we eat and drink. The senses of taste and smell also function to warn us of dangers and poisons, and to identify nutrients. Alterations in the experience of taste and smell may present at different stages of several cancers, including lung cancer, and have been reported to affect food choice, nutritional intake, social activities and emotional well-being. Lung cancer is the cancer form that causes most cancer-related deaths and, since a large proportion of those diagnosed with lung cancer have advanced disease, the goal of treatment is often to maintain quality of life. Weight loss and nutritional problems such as loss of appetite, early satiety and taste and smell alterations have been reported to be common symptoms among people with lung cancer. Primarily, taste and smell alterations have been studied in relation to cancer treatment, but there are indications that they can be present even before treatment start. Taste and smell alterations can have various characteristics, e.g. changes in the experience of intensity of basic taste qualities or odours, a bad taste in the mouth, a metallic taste or changes concerning specific foods. Although a small number of studies have investigated how taste and smell alterations develop over time, it is not known how the characteristics of taste and smell alterations change over time. General guidelines for how health care professionals can support people with taste and smell alterations are often lacking. Taste and smell alterations have been described as being a neglected problem within healthcare and health care professionals have reported being unable to support people with taste and smell alterations in a satisfactory manner. How people who experience taste and smell alterations reason about resources and strategies to manage these symptoms has not yet been investigated. Therefore, the overarching aim of this thesis is to investigate the nutritional importance of taste and smell alterations, their characteristics and how people deal with them in different stages of investigation and treatment of lung cancer.

Methods: This thesis consists of three papers which use data from two studies within a larger research project, the Taste and Smell project: a longitudinal observational study with the aim of investigating the effect of taste and smell alterations on nutritional status and well-being among people in different stages of cancer, and a qualitative study with the aim of exploring how people with taste and smell alterations reason about strategies and resources for managing taste and smell alterations. In the longitudinal observational study, which provides data for paper I and paper II, participants under investigation for lung cancer were recruited and data were collected using structured, face-to-face interviews based on four self-report instruments concerning 1) taste and smell alterations, 2) common cancer-related symptoms, 3) well-being, and 4) nutritional status. After the first structured interview, up to three follow- up interviews were conducted at two-month intervals using the same instruments. In paper I, data were included from participants who were under investigation for lung cancer and who later were either diagnosed with lung cancer or did not receive a cancer diagnosis of any type. Descriptive and inferential statistics were used to study the prevalence of self-reported taste and smell alterations among study participants under investigation for lung cancer, and the relationships between taste and smell alterations and demographic and clinical characteristics, weight change, symptoms and changes in food intake. In paper II, data were selected from those who were treated for lung cancer and who had participated in at least three of the four structured interviews. Through systematic use of the data on self-reported taste and smell alterations, characteristics of taste and smell alterations were categorized for each individual and changes in characteristics over time were studied on an individual level. Furthermore, individual case descriptions for three persons were performed, based on information from all four self-report instruments in combination with the interviewer’s field notes. In the qualitative study, which constitutes the basis for paper III, data were collected through semi- structured interviews with informants with experience of lung cancer-related taste and smell alterations. The interview transcripts were analysed inductively and the analysis was interpreted using the medical anthropological model of health care systems developed by Kleinman.

Results: Taste and smell alterations, although relatively mild, were reported by 38% of study participants under investigation for and also later diagnosed with lung cancer (paper I). Among those who did not receive any cancer diagnosis, the proportion of study participants reporting taste and smell alterations was similar, 37%. However, there was a statistically significant relationship between taste and smell alterations and weight loss only among those with lung cancer. We found a large individual variation in characteristics of taste and smell alterations among those who were treated for lung cancer, and several participants reported changes in characteristics of taste and smell alterations over time in relation to treatment start (paper II). Distress from and consequences of taste and smell alterations appeared to not only depend on the characteristics of the alterations but also on, for example, the individual’s life situation and concurrent symptoms such as loss of appetite or nausea. When participants in the qualitative study described how they managed taste and smell alterations, it was clear that most management took place in their daily life without much engagement from health care professionals (paper III). Management strategies were found to concern two overarching challenges: to adjust to no longer being able to trust the information provided by one’s own senses of taste and smell, and to come to terms with taste and smell alterations as a part of having lung cancer. The involvement of health care professionals was limited, but appeared to fulfil most participants’ expectations and seemed to have potential to influence strategies and resources used for dealing with taste and smell alterations.

Conclusion: In summary, this thesis has furthered the understanding of the implications of cancer-related taste and smell alterations and the individual variation regarding their impact on food intake, their characteristics and how people deal with these symptoms in their daily life.