By a Cambridge Medical Student
Below is a table showing the estimated data for several of the most well-known cancers in the UK in 2012 for both sexes.
The incidence of a cancer is the number of new patients diagnosed each year per 100,000 people. So, with lung cancer, for every 100,000 people in the UK, 30 of them were diagnosed with lung cancer.
The mortality rate is the number of deaths each year per 100,000 people. So, with lung cancer, for every 100,000 people in the UK, 25.4 died from lung cancer.
The incidence to mortality rate ratio essentially represents the likelihood of one dying after having been diagnosed with a cancer. For example, with Kaposi Sarcoma, for every 34 people diagnosed with the cancer, 1 person will die; this cancer shows a very high survival rate. However, with lung cancer, the very low incidence to mortality rate ratio of 1.18 essentially shows that for every 118 people diagnosed with lung cancer, 100 of them will die; lung cancer then has a very low survival rate.
This low incidence to mortality rate ratio is one of the main reasons why lung cancer is one of the most common causes of death in the UK. Looking at the table once more, we can see that the (age standardised) incidence of lung cancer isn’t the greatest out of all the cancers, yet the (age standardised) mortality rate is; meaning that whilst lung cancer isn’t the most common cancer in terms of the number of individuals that have it, it still, nevertheless, causes the most deaths out of all the other cancers. This section examines the current healthcare system in the UK to find out why so few people are surviving the disease after having been diagnosed.
Before we look at current treatment for the disease and examine its effectiveness, we must look at how lung cancer is diagnosed in the first place.
A patient will usually come to their GP with symptom(s) of lung cancer, such as a persistent cough, breathlessness or coughing up blood. The patient would then be sent off to have a blood test to rule out other possible causes of their symptom(s), such as a chest infection. Once these other possible causes have been ruled out, the patient is referred for a chest X-ray.
Most lung tumours show up on chest X-rays as a white/grey mass, however a definitive diagnosis cannot always be given since chest X-rays cannot always distinguish between cancer and other conditions. Therefore, if the chest X-ray suggests the patient may have lung cancer, the patient is referred to a specialist in chest conditions who will arrange for more tests that will establish whether the patient really does have cancer and, if they do, what type and stage it is.
The next step after a chest X-ray is to have a CT scan. If the results of the CT scan indicate the patient has lung cancer at an early stage, a PET-CT scan will follow to determine how active the cancer cells are. If the results of a CT scan show cancer in the central part of a patient’s chest, a bronchoscopy will follow. In this procedure, a bronchoscope examines the patient’s lungs and takes a biopsy.
Once all these tests have been taken, the stage of the disease can be determined and the treatment is carefully planned around this and soon follows.
All this seems very efficient, however, the reality is that the average waiting time between GP referral and initiation of lung cancer treatment was around 60 days in 2007. Government guidelines currently state that patients should wait no longer than 62 days before starting treatment after an urgent GP referral, however in 2013, it was found that, across England, only 80.4% of lung cancer patients were meeting this guideline with proportions varying between providers.
Reasons for long waiting times include long waiting lists for various diagnostic tests (e.g. CT scans), limited availability of radiotherapy facilities, scarcity of trained thoracic surgeons and limited theatre time. For certain patients, multiple investigations are required to diagnose and stage the cancer and multiple MDT meetings may also be required before starting treatment. This all adds to the waiting time for such a patient.
In this long waiting time, the cancer may grow and begin to spread, making the disease much harder to treat. Thus, long waiting times can be argued to be one of the reasons why lung cancer is such a common cause of death in the UK: patients cancer’s may grow and spread during the long periods of time they idly wait to begin treatment, worsening their prognoses.
It should also be mentioned that there is a lot of overlap in early stage lung cancer symptoms with symptoms of other health conditions and so patients aren’t routinely sent for X-rays and CT scans. Also, when a patient is sent for an X-ray, the lesion can sometimes be very small and so may not be detected. Both of these factors lead to a delay in the diagnosis of the disease which, again, worsens the prognosis for the patient.
The waiting time between onset of symptoms and beginning of treatment isn’t the only period of time that can be blamed for the high mortality of lung cancer; the time between the first cancerous change and the onset of symptoms is also very lengthy, with patients often only becoming symptomatic when the tumour has become large. Thus, when patients do become symptomatic, the cancer is most likely to be at a more advanced stage and so is less treatable. The table below, consisting of data obtained by the Anglia Cancer Network, shows the percentage of patients diagnosed with each stage of lung cancer. Number and Proportion of Cases Diagnosed at Each Stage, Adults 15-99, Former Anglia Cancer Network
As we can see, the majority of patients diagnosed with lung cancer have an advanced stage of the disease (III or IV). This is due to patients being asymptomatic for a very long time and the overlap of early stage lung cancer symptoms with symptoms from other health conditions.
The graph and associated table below visually demonstrates that surviving lung cancer very much depends on the stage of the disease upon diagnosis, with advanced stage lung cancers having poor prognoses.
One-Year Relative Survival Rates by Stage, Adults Aged 15-99 Years, Former Anglia Cancer Network
Thus, we can conclude that another reason why lung cancer is such a common cause of death in the UK is because the majority of patients diagnosed with the disease have an advanced stage lung cancer which, unfortunately, is less treatable and have worse prognoses than early stage lung cancers.
One way to overcome this problem is by lung cancer screening (testing people for lung cancer before they have any symptoms). This would allow early stage lung cancers to be identified, thus increasing the chance that the patient can be cured. There is currently no national screening programme for lung cancer in the UK. Cancer Research UK gives the following reasons for this:
Lack of a sensitive enough test
Low number of cancers that would be found
High costs involved
Risk of current tests
Researchers are currently trying to find a suitable test to be used on groups of people who are at a high risk of developing lung cancer (long-term smokers, people with previous lung disease, people who have been exposed to asbestos etc.).
So, in the near future, tests such as a Spiral CT (low dose CT scan), fluorescence bronchoscopy (use of blue and white light to examine the lining of the airways) and even tests that look at chemical changes in the body that may be indicative of lung cancer may become part of a national screening programme. But, for the time being, lack of such a screening programme is another reason why lung cancer is such a common cause of death in the UK; early stage lung cancers are rarely being detected, leading to more deaths.
Having now looked at the diagnosis of lung cancer and the problems associated with it, we will now look at current treatment for the disease and examine how well it is destroying the cancer and thus preventing death.
3.2 Current Treatment
Treatment is planned around the type and stage of the cancer, where it is located within the lung, the patient’s general health and the patient’s own wishes. As a result, treatments vary significantly between lung cancer patients.
For early stage SCLC, the patient is likely to have chemotherapy and then radiotherapy to the lung, with fairly fit patients having both at the same time. For patients whose lung cancer shrinks with this treatment, radiotherapy to the brain usually follows to kill any cancer cells that may have spread there. For SCLC that has spread to other areas of the body, treatment also involves chemotherapy and radiotherapy but the patient could alternatively have treatment that only relieves symptoms (palliative care) if the cancer is deemed to be incurable.
For early stage NSCLC, a lobectomy or pneumonectomy is usually carried out, followed by chemotherapy to lower the risk of the cancer coming back. If the patient is unable to undergo surgery, radiotherapy or chemoradiation is offered.
For stage 3 NSCLC, surgery may be offered depending on the location of the cancer. If surgery isn’t offered, then radiotherapy/chemotherapy will be.
For stage 4 NSCLC, treatment aims to control the cancer, not cure it, by shrinking the tumour to reduce symptoms. Some patients may be offered targeted cancer therapy drugs (these act on molecular targets associated with cancer to prevent the growth and spread of the cancer), such as erlotinib, to control symptoms. These drugs have been shown to improve patient survival rates in clinical trials and they are likely to form a greater part of cancer treatment in the future.
Five year survival rates are shown and it further emphasises the fact that advanced stage cancers have a far worse prognosis than early stage ones.
Five-Year Relative Survival Rates by Stage, Adults Aged 15-99 Years, Former Anglia Cancer Network
These saddening figures show that current treatment for lung cancer, whilst it appears to be very structured and organised, is proving to be largely ineffective at preventing death, particularly for patients with advanced stage cancers; this ineffective treatment is another reason why lung cancer kills so many people.
One of the reasons why treatment often fails to cure patients, ignoring the stage of the disease for one moment, is because the majority of lung cancer patients are smokers and most of these smokers have various other health conditions which means they often simply aren’t well enough to manage their lung cancer treatment. As a result, they may have to be taken off treatment so that their condition doesn’t worsen. This eventually leads to the cancer killing them. This unfortunate fact is another reason why lung cancer is such a common cause of death.
However, as more targeted cancer therapies that attack cancer at a molecular level are being introduced, we can expect five year survival rates to go up, particularly in more advanced stage cancers. 70 Furthermore, if a national screening programme for high risk individuals were to be introduced, this would allow more early stage cancers to be diagnosed; improving the prognosis for these patients (as treatment would be more effective) and thus reducing the total number of lung cancer deaths. Further Reading:
1. (2014). Targeted Therapies Improve Prognosis for Lung Cancer Patients. Available: http://www.uchospitals.edu/news/features/lung-targeted-therapies.html. Last accessed 27th August 2014.
2. Devbhandari, M et al. (2007). UK waiting time targets in lung cancer treatment: are they achievable? Results of a prospective tracking study. Journal of Cardiothoracic Surgery. 2:5