MEDICAL MATTERS:Research offers hope to victims of the disease
THE RECENT media focus on cancer of the pancreas is a reminder that, despite the enormous strides made in cancer treatment in recent times, some cancers continue to have a poor prognosis. Lung cancer, the third most common cancer in Ireland is one of these; less than 10 per cent of people with the disease are still alive five years after diagnosis. It is the most common cause of death from cancer in this country; some 1,623 Irish people died of lung cancer in 2006.
Why such a miserable outcome? There are several reasons. Lung cancer is especially prevalent in working class areas where smoking levels are highest; it is usually diagnosed quite late in the illness, meaning the disease has had time to spread; there is no reliable screening test for lung cancer; and because of its close link with smoking it is seen, to some extent, as self-inflicted, a characteristic that has promoted a certain public and professional nihilism towards the disease.
With more women smoking than before, female lung cancer rates are on the rise. And there has been an interesting change in the type of cancer diagnosed in both sexes, with a drop in squamous cell cancers and an increase in adenocarcinomas. Some experts have linked this to a reduction in the use of unfiltered cigarettes.
There has also been a reduction in the risk of dying from the disease. Latest National Cancer Registry figures show the risk of dying from lung cancer for men younger than 75 has dropped from one in 18 to one in 26.
A report in last week's British Medical Journalconfirmed that, despite the introduction of a cancer control plan for England in 2000, there is still evidence of inequalities in cancer care. It found that more than one half of lung cancer patients were admitted as emergencies, a proportion that had increased over the decade.
And older people, women and those from deprived areas were more likely to be admitted as emergency cases rather than for planned treatment.
The British Thoracic Oncology Group (BTOG) is holding its annual meeting in Dublin this week. Its chairman, Prof Ken O’Byrne, says the programme promises some good news for patients. A consultant oncologist at St James’s Hospital in Dublin, O’Byrne points to advances in molecular biology and diagnosis as key areas of progress.
“Recent advances in our understanding of the molecular biology of non small cell lung cancer [NSCLC], how the cancer develops, grows and spreads, has led to the identification of a number of important growth factors that can be targeted with novel agents.
“These include monoclonal antibodies and small molecules that directly switch off growth signals in the cancer cells. A number of these have made the important step from the bench-to-the-bedside and, as a result, have improved the outlook for patients with the disease.”
These drugs include erlotinib (Tarceva) and gefitinib (Iressa). They target the epidermal growth factor receptor (EGFR) and work by switching off growth signals in cancerous cells.
According to O’Byrne, recent studies have shown dramatic tumour shrinkage in more than 70 per cent of cases. Although not curative, these agents appear to add about 18 months to overall survival in a sub-group of patients with advanced inoperable disease.
“We are also recognising that the histology of the cancer is important in determining the treatment we should administer. A recent trial has shown that patients with squamous cell cancer of the lung, a subtype of NSCLC, are probably best treated with gemcitabine while non-squamous cell NSCLC, including adenocarcinomas, probably benefit from the drug pemetrexed,” O’Byrne notes.
What about diagnosing lung cancer at an earlier stage? A recent conference organised by the American Association for Cancer Research heard about progress in the development of biomarkers in the form of a blood test offering the prospect of more accurate diagnosis.
Could there be light at the end of the lung cancer tunnel?
mhouston@irishtimes.com