It is the most feared cancer, a silent killer with few symptoms, but progress is being made in treating it, writes RONAN McGREEVY
THERE IS NO cancer more feared than lung cancer. Not only does it kill more people than any other cancer in Ireland, 1,800 last year alone, it has proved to be stubbornly resistant to many of the treatments that have dramatically improved survival rates for other cancers.
Where a sizeable number of patients have a reasonable expectation of still being alive five years after diagnosis for most cancers nowadays, the survival rate for lung cancer is just 12 per cent.
The potency of lung cancer as a killer is a direct result of its tendency to attack one of the vital organs in the body and its status as a silent killer. Lung cancer does not manifest itself in most cases until it is too late for unfortunate sufferers.
In Ireland, 70 per cent of lung cancer patients present with advanced symptoms of the disease. The other 30 per cent present with lung cancer which is resectable; that is a part of the lung is removed – the most effective way of curing the illness.
This operation is only possible if the patient is fit enough to undergo such treatment and many are not because of age or the damage that smoking has done to their lungs.
All is not lost though. According to Prof Ken O’Byrne, one of the leading experts on the disease in Ireland, solid progress is being made at home and abroad in treatment of this deadly disease.
Prof O’Byrne, a consultant oncologist at St James’s Hospital, says this is a time of “great optimism” in lung cancer. Treatment for patients has rapidly improved with the assembly of multidisciplinary teams to tackle the disease in all of the country’s eight centres of excellence.
One type of multidisciplinary team is involved in the diagnosis and treatment of patients. This involves surgeons, radiation oncologists, specialist nurses and palliative medicine specialists, and the aim is to get patients into treatment within eight weeks.
The other type of multidisciplinary team provides support during treatment. They include specialist nurses, dieticians and physiotherapists to provide a holistic approach to treatment.
This approach ensures the optimal treatment can be given to patients at the earliest possible opportunity, prolonging life expectations and ameliorating the symptoms of this disease.
The source of greatest optimism surrounds sub-sets of patients who have small mutations or abnormalities in their tumours. Those gene mutations cause “oncogene addiction” where the tumour is addicted to the signalling provided by a mutated gene.
“It is a bit like a light switch. When you have this mutation, the light switch is switched on permanently. Those tumours are addicted to that gene,” he explains.
Between 13 per cent and 15 per cent of patients with lung cancer now have a genetic mutation for which there is a treatment.
Approximately 10 per cent are receiving epidermal growth factor receptor drugs which have doubled the life expectancy of those who present with the advanced stages of the disease, albeit from a low base. Previously the average life expectancy of those patients was 10 to 12 months; now it is two years.
Similarly, between three and five per cent of lung cancer patients have an anaplastic lymphoma kinase (ALK) protein that stimulates cancer cells to grow.
A drug called Crizotinib blocks the protein from over-stimulating the cancer cells and stops the tumour growing for a time. This manages to halt the growth of the cancer cells for about nine months, prolonging the life of suffers for two years.
It is far from a cure, but O’Byrne says they are at the start of a process which could dramatically improve the life-expectancy of lung cancer patients.
About 55 per cent of lung cancer patients carry a specific gene abnormality, and researchers have drugs in clinical trial for two types of these patients.
“We’re beginning to increasingly understand the molecular biology of lung cancer and the genes that drive this address. We are now understanding that patients have different genetic abnormalities that drive the cancer,” he explains.
“We are discovering more and more of these with time and it is happening very quickly now. We believe we are going to have a whole range of drugs to treat this disease.”
The goal is to move towards “personalised medicine” where biopsies are carried out and analysed for these genetic markers. The results should show if it will then be possible to decide whether or not these new targeted treatments or chemotherapy – or a mixture of both – are most appropriate. These drugs have offered hope for lung cancer patients, but the greatest way to avoid the disease is not to smoke.
Lung cancer is overwhelmingly related to tobacco use, with 85 per cent of those who contract the disease being current or ex-smokers.
The biggest cause of lung cancer’s deadly advance is the lateness of diagnosis. Most lung cancer symptoms are mistaken for more common ailments such as a bad cough or a chest complaint and the eventual diagnosis is devastating.
To date, there has been no effective screening programme for the disease, but new research in the US could lead to a breakthrough. Because of its association with smoking, at-risk people are relatively easy to identify.
In the US, a national lung-screening trial, the results of which were published in the New England Journal of Medicine last month, found that screening using a CT scan reduced the number of people dying of lung cancer by 20 per cent. A CT scanner has proved to be much more efficient than chest X-rays in picking up the disease at an early stage.
“That represents a potentially major breakthrough, but we need more data,” O’Byrne cautions.
A similar trial, called the Nelson trial, is being carried out in Europe and it will report more updated results soon. It found that CT detected four-fifths of participants’ lung cancers at stage one – in time to effect a curative resection.
O’Byrne stresses that while medical breakthroughs are offering hope for patients, lung cancer is avoidable if people do not smoke, and none of the treatments involved offer a licence for those at risk to continue smoking.
O’Byrne says that if everybody stopped smoking and there was no new smokers for the next 20 years, the incidence of lung cancer would be halved.
“No cigarettes and lung cancer disappears, pretty much,” he says.
