High Prevalence of Dyspnea in Lung Cancer: An Observational Study

INTRODUCTION

The terms “breathlessness” and “dyspnea” have been used interchangeably in literature and often point to the same sensation of difficult/labored breathing.[1] It is one of the most common symptoms in advanced cancer.[2] In a systematic review by Viniol et al. in 2015, the authors report that 0.8%–0.59% of the general population experiences dyspnea.[1] Analysis of secondary data from the World Health Survey 2002 for India reports these figures as 7.2% – much higher than elsewhere in the world. Lung cancer is one of the most common causes of dyspnea seen in 60% of such patients.[3] A cross-sectional study done in our center by Damani et al. reported the clinical prevalence of dyspnea as 44.37% in patients with advanced cancer.[4] The concept of “dyspnea” as a symptom has seen marked evolution in recent times and has led to expert consensus on the term “chronic breathlessness syndrome” – defined as breathlessness that persists despite optimal treatment of the underlying pathophysiology, resulting in disability. Interestingly, a stated duration is not needed for classifying it as “chronic.”[5] Seminal work has been done in Europe but not in India where the burden is probably more.[6] This study is a secondary analysis to seek the clinical prevalence of dyspnea on a subset of patients with lung cancer. The findings will help us understand the magnitude of dyspnea in patients with lung cancer and prioritize symptom management based on its associations.

MATERIALS AND METHODS

This was a subset analysis of lung cancer patients of a prospective observational study done over 6 months from April to September 2014 at the Department of Palliative Medicine, Tata Memorial Centre (Mumbai). All patients presenting to the outpatient clinic of the palliative care service were screened and accrued as per the inclusion criteria – all literate adult patients with advanced lung cancer with normal cognitive status with the ability to understand the nature of the study and who provided informed consent. We excluded patients on ventilators/noninvasive ventilation or on disease-modifying therapy. Compensation in any form was not provided for taking part in this study, and diligence was taken to protect patients’ confidentiality. The trial is registered with Clinical Trials Registry of India (CTRI REF/2014/05/006948). All study-related procedures including data collection were done by the author and coauthors; all physicians trained in palliative medicine who did a one-time assessment of the participants during their first visit. It involved medical consultation, recording of sociodemographic information, symptom scores using Edmonton Symptom Assessment Scale (ESAS), performance score using Eastern Cooperative Oncology Group (ECOG) scale, dyspnea by Cancer Dyspnea Scale (CDS), and quality of life (QoL) of the patients using European Organization for Research and Treatment of Cancer QoL Core 15 Palliative (EORTC QLQ-C15-PAL) questionnaire.

RESULTS

A sample of 500 patients was recruited for the original study, of which 42 (8.4%) had primary cancer of the lung.

DISCUSSION

This study shows that breathlessness is a common symptom in patients with advanced lung cancer (seen in 71.43%) – higher than seen in a systematic review (19%–51%).[3] This is probably because none of the research articles included were from India and can also be attributed to differences in patient selection, lack of clear symptom definition, and variation in dyspnea measurement techniques. In our study, patients reported the perceived sense of effort of breathlessness as most bothersome. This was also associated with multiple other symptoms – fatigue, anxiety, appetite, and loss of well-being items on ESAS and lower QoL in the patients. These were consistent with a study done by Polanski et al.[7] Scoping search on breathlessness in lung cancer in the Indian context showed no published literature. Major strengths of this study lie in its prospective design and usage of validated tools. There are a few limitations – these results are from a subset analysis of the original larger study, and there are chances of selection bias. To overcome it, we matched the relative proportion of lung cancer patients in our cohort with annual hospital data which was comparable. There might be contributory thoracic pathology which might overestimate the prevalence of dyspnea; however, as a part of standard care, most of our patients would have been treated for underlying correctable causes for dyspnea. The use of single-item tool (ESAS) to measure anxiety and depression might be inadequate; instead, a more specific tool such as the Hospital Anxiety Depression Scale would have been better.[8] The temporal relationship between dyspnea and QoL cannot be evaluated in this study because both were assessed at the same time.

Future studies should consider longitudinal designs on wider populations, also qualitative research to gain a deeper understanding of the issues affecting breathlessness.

CONCLUSIONS

The prevalence of breathlessness in lung cancer patients was high (71.43%). Patients described it as an increased sense of effort for breathing, and it was associated with multiple factors such as fatigue, anxiety, and low QoL.