Some lung cancers linked to common virus
Washington: A common virus known to cause cervical and head and neck cancers may also trigger some cases of lung cancer, according to new research led by an Indian-origin scientist.
The study by Fox Chase Cancer Center in US examined tissue samples from lung cancer patients and found that nearly 6 per cent showed signs they may have been driven by a strain of human papillomavirus (HPV) known to cause cancer.
If HPV indeed plays a role in lung cancer in some patients, the next step is to better understand those tumours so they can be treated more effectively.
"The ultimate goal is to determine if we can target our therapies to the specific characteristics of these tumours," said study author Ranee Mehra, attending physician in medical oncology at Fox Chase.
Studies from Asia have shown that lung tumours are frequently infected with HPV. The pattern makes sense, explained Mehra - the lungs are located near the head and neck region, which is known to be at risk of tumours upon exposure to some strains of HPV.
To investigate, she and her colleagues examined 36 tissue samples from people diagnosed with non-small cell lung cancer who had never smoked, part of the Fox Chase Cancer Center Biosample Repository.
The reason they chose non-smokers, Mehra explained, is that smoking is a major cause of lung cancer - but in non-smokers, the explanation is often less obvious.
The researchers found that 4 out of 36 samples had signs of infection from two strains of HPV known to cause cancer, 16 and 18. Looking more closely at the two samples infected by HPV 16, Mehra and her team saw signs the virus had integrated into the tumour`s DNA - which is even more suggestive that the infection caused the tumour.
Although this suggests that HPV drives lung cancer in less than 6 per cent of non-smoker patients, making it a relatively rare occurrence, lung cancer is very common, Mehra noted - killing more than 1 million people every year.
Approximately 10 per cent of cases occur in non-smokers.
"Given how many patients develop lung cancer, if even a small percentage of those tumours stem from HPV, that ends up being a large number of patients," she said.
It`s not clear how HPV reaches the lung, she said; patients may simply breathe it in. And just because these patients have evidence of an HPV infection that does not necessarily mean the infection caused their tumours, Mehra cautioned.
"It could simply be a coincidence that they had both lung cancer and HPV. But the presence of both simultaneously, and the integration of the virus into the tumour`s DNA, fuels the hypothesis that they are related," she noted.
The study was presented at the annual meeting of the American Association for Cancer Research in US.