O'Dowd, Emma Louise
(2017)
Factors influencing the diagnosis and subsequent prognosis in patients with lung cancer.
PhD thesis, University of Nottingham.
Abstract
Background
The United Kingdom (UK) has poor lung cancer survival rates compared to other countries, and this is partly explained by differences in early mortality. In order to diagnose lung cancer at an earlier stage in the UK there is a pressing need to understand the management process from the recognition of symptoms by people with lung cancer, through the initial interactions with primary care to the referral to secondary care and the choice of the subsequent treatment plan.
Objectives
The aim of this thesis is to use mixed methods to identify some of the factors which may affect the diagnosis and prognosis in patients with lung cancer in the United Kingdom across the whole patient pathway.
Methods
Prospectively collected clinical data were used in conjunction with qualitative methodology. Primary care records were obtained from The Health Improvement Network, alongside data from the National Lung Cancer Audit (NLCA), linked to Hospital Episode Statistics and Office for National Statistics datasets. Case-control and cohort studies were conducted using multivariable logistic regression to look at independent associations with early mortality, likelihood of receiving surgery and place of death. Survival analyses were performed using Kaplan Meier curves and Cox regression and validation studies used area under the receiver operating curves (AUC). The Framework approach was used to identify themes and sub-themes arising from focus group interviews.
Results
Mixed methods were used to look at barriers to early diagnosis and attitudes towards lung cancer screening in a high risk population. A number of key practical and emotional barriers which may impact on screening uptake were identified, alongside the issue of smoking stigma and blame. Primary care data were used to look at predictors of early (0-90 day) mortality in the UK. Thirty per cent of patients with lung cancer died within 90 days of diagnosis. Increasing age, male sex, socioeconomic deprivation, rural versus urban location and current smoking were all independently associated with early death. Patients who had poorer prognosis did interact with primary care before diagnosis, suggesting missed opportunities to identify them earlier. NLCA data linked to organisational audit data highlighted inequities between Trusts, in particular with regards to variability in the workload of specialists and differences in access to diagnostic and therapeutic modalities. On site access to positron emission computed tomography, stereotactic ablative radiotherapy and video-assisted thoracoscopic lobectomy were independently associated with increased likelihood of receiving surgery for lung cancer. Records for patient who developed brain metastases following radical surgical treatment for lung cancer were reviewed. Those with more advanced disease stage, younger age and adenocarcinoma sub-type were more likely to develop metastases and modelling suggested that 71% may have been visible pre-operatively had magnetic resonance imaging of the brain been performed as part of the staging process. An internal and external validation was performed to assess the ability of two risk scoring systems to predict 90 day post-operative mortality. AUC values for internal and external validation of the NLCA score and validation of Thoracoscore were 0.68 (95% CI 0.63-0.72), 0.60 (95% CI 0.56-0.65) and 0.60 (95% CI 0.54-0.66) respectively. Post-hoc analysis was performed using NLCA records on 15554 surgical patients to derive summary tables for 30 and 90 day mortality, stratified by procedure type, age and performance status. Linked NLCA data were used to look at place of death from lung cancer. Thirty-five per cent of patients with lung cancer die in acute hospital beds, with male sex, old age (≥ 85 years), socioeconomic deprivation, WHO performance status 4 at diagnosis and emergency route to diagnosis all independently associated with increased likelihood of death in this setting. There is marked geographical variation in place of death, particularly with regard to provision of hospice services.
Conclusions
The studies described in this thesis use prospectively collected data to provide a snapshot of different aspects of the lung cancer patient journey which may impact on prognosis, alongside qualitative methodology to try to determine reasons for diagnostic delay and attitudes towards screening programmes. There remain some important clinical questions about lung cancer care and outcomes which need to be looked at to provide a greater understanding of where the inequities in the lung cancer patient pathway in the UK lie and to try to address modifiable factors with an aim to improve outcomes.
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