Tuesday October 14 2014
A persistent cough is often the first sign of lung cancer
"Doctors in Britain are 'missing opportunities' to spot lung cancer at an early stage," BBC News reports. A study found around a third of people with the condition die within 90 days of their initial diagnosis.
The study looked at the medical records of more than 20,000 adults who had been diagnosed with lung cancer in the UK between 2000 and 2013.
They found people were more likely to die early if they were male, over the age of 80, currently smoking, were socioeconomically deprived, or lived in rural areas. They were also less likely to have had a chest X-ray requested by their GP in the four months before diagnosis.
While the study found associations between factors, it cannot say for certain whether symptoms were missed. For example, there may be a variety of reasons why a chest X-ray was not requested – some people may not have had or reported symptoms of lung cancer, or may not have wanted further investigations.
Smoking is still the biggest risk factor for developing lung cancer, so visit the NHS Choices Stop Smoking guide for ways to help you quit.
You should always visit your GP if you develop a persistent cough, cough up blood, or have persistent breathlessness.
Where did the story come from?
The study was carried out by researchers from the University of Nottingham and Nottingham City Hospital. It was funded by the Roy Castle Lung Cancer Foundation.
The study was published in the peer-reviewed medical journal Thorax on an open access basis, so it is free to read online (PDF, 727.2kb).
The media focused on blaming GPs for missing or delayed cancer diagnosis without considering that this research cannot tell us for certain what the causes of early lung cancer deaths are. It can only identify links that need to be investigated further.
This could include collecting details the current study did not have on individual patients, such as why they were visiting their GP, other illnesses, if they had any symptoms, and also whether the lung cancer was actually the cause of death.
There are anecdotal reports that many "hard core" smokers mistake the persistent cough associated with lung cancer for a "smoker's cough". This could contribute towards the pattern of late diagnosis seen in this study.
What kind of research was this?
This was a cohort study looking at the factors linked with early death from lung cancer in the UK. This included looking at whether there was any link with the number of GP visits and if a chest X-ray had been performed in the four months prior to diagnosis.
The researchers say the UK has poor lung cancer survival rates compared with other countries, and this could be associated with late diagnosis.
This type of study is appropriate for looking at this question, and it benefits from using data recorded at the time.
However, as the data wasn't collected expressly for this study, there may be information missing that the researchers would have liked to have but didn't get (for example, why the person went to the GP in the first place).
The main limitation is that although the study can identify associations between factors, it cannot show with certainty whether they definitely contributed to the outcome (early death).
What did the research involve?
The researchers looked at the records of adults over the age of 30 who had been diagnosed with lung cancer between January 2000 and January 2013.
They compared people who survived for more than 90 days following diagnosis with those that did not in terms of:
- characteristics (gender, socioeconomic level and smoking status)
- number of visits to the GP in the four months before the lung cancer diagnosis
- if a chest X-ray had been requested by the GP in the four months before diagnosis
People were excluded from the study if they had been registered with their GP for less than 12 months.
The researchers obtained the data from a database called The Health Improvement Network (THIN), which contains data on symptoms, diagnoses, prescriptions, medical investigations and their results entered by GPs during appointments or based on information sent to the GP by secondary care.
What were the basic results?
The researchers identified 20,142 people who had been diagnosed with lung cancer from 444 GP practices. Of these:
- 5% were only diagnosed once they died (diagnosis only on their death certificate)
- 10% died within 30 days of the diagnosis
- 15% died between 30 and 90 days of diagnosis
- 70% survived for longer than 90 days
People who died early (within 90 days of diagnosis) had visited their GP on average (median) five times in the four months before diagnosis, compared with four times for those who survived for longer. People who had a chest X-ray requested by their GP were less likely to die within 90 days.
When looking at each GP practice as a whole, people registered at practices that requested more chest X-rays were more likely to die early (comparison of practices with highest rates versus those with the lowest: odds ratio [OR] 1.41, 95% confidence interval [CI] 1.29 to 1.55).
Characteristics associated with an increased likelihood of dying early were:
- being male (OR 1.17, 95% CI 1.10 to 1.24)
- being a current smoker (OR 1.43, 95% CI 1.28 to 1.61)
- being older (aged 80 years or more compared with aged 65 to 69: OR 1.80, 95% CI 1.62 to 1.99)
- being socially deprived (Townsend quintile five [most deprived] versus one [least deprived] OR 1.16, 95% CI 1.04 to 1.30)
- living in a rural area (OR 1.22, 95% CI 1.06 to 1.41)
How did the researchers interpret the results?
The researchers concluded that, "Patients who die early from lung cancer are interacting with primary care prediagnosis, suggesting potentially missed opportunities to identify them earlier.
"A general increase in CXR [chest X-ray] requests may not improve survival; rather, a more timely and appropriate targeting of this investigation using risk assessment tools needs further assessment."
This study found people who die early after their lung cancer diagnosis (within three months) were less likely to have had a chest X-ray and tended to have more GP visits on average in the four months prior to their diagnosis than those who lived longer.
The researchers suggest that this could indicate there are "missed opportunities to identify them earlier", and this is what the media has focused on.
While the study found an association with the number of GP visits, the difference is relatively small (one visit on average). There are many factors that could have accounted for the number of visits made to the GP, as well as other issues that were not assessed in this study. These include:
- whether the people in each group actually had (or reported to their GP) symptoms of lung cancer
- whether the lung cancer was the cause of death or the person died from other causes
- whether there were any other (non-cancer) illnesses present that may have been the reason for the GP visits
- whether a patient preferred not to have investigations such as a chest X-ray
The researchers also did not have information on the stage of people's lung cancer when they were diagnosed to confirm that these people were diagnosed late.
Some of the other findings of the study – such as the fact that those dying early tended to be older, male smokers who lived rurally and in more socially deprived areas – have not been focused on by the media. These findings may offer insights into those who might, for example, be targeted for lung cancer symptom awareness.
Lung cancer remains one of the most common types of cancer in the UK, and has one of the lowest survival outcomes. Important research such as this investigates reasons why this might be, and how the outlook could be improved.
One of the problems with lung cancer is there are usually no signs or symptoms in the early stages of the disease. The symptoms that people may develop later on include:
- a persistent cough
- coughing up blood
- persistent breathlessness
- unexplained tiredness and weight loss
- an ache or pain when breathing or coughing
You should always see your GP as soon as possible if you have any of these symptoms.
Smoking is still the biggest risk factor for developing lung cancer – if you smoke, quitting is the best way to reduce your chances of developing this disease. Visit the Stop smoking guide for ways to help you quit.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.