Although the link between viruses and cancer has long been established, it is only recently with the introduction of vaccines against human papillomavirus (HPV) that in-roads have been made into exploiting this connection for preventative purposes. Now it seems that more cancers may have a viral link, in particular to HPV, raising the possibility that these tumours could be prevented by vaccination.
Scientists from the University of Louisville presented data at the 1st European Lung Cancer Conference, held from 23rd to 26th April, in Geneva, Switzerland, suggesting that HPV may contribute to the development of non-small cell lung cancer (NSCLC). The researchers examined 23 NSCLC samples from patients in Kentucky and found six tested positive for the presence of HPV, the virus that causes many cases of cervical cancer (CC), and is also known to be carcinogenic or co-carcinogenic in anogenital, oropharyngeal and oesophageal cancer. One sample was later shown to be CC that had metastasised to the lungs.
Of the remaining five virus-positive samples, two were found to be HPV type 16, two were HPV type 11 and one was HPV type 22. According to the study authors, the fact that five out of 22 NSCLC samples were HPV-positive supports the assumption that the virus contributes to the development of the disease. All the patients in this study were also smokers, leading the researchers to hypothesise that HPV has a role as a co-carcinogen, which increases the risk of cancer in a smoking population. Of particular interest to the investigators was the fact that the virus was present in the lung tumours themselves, but not in the surrounding tissue, lending credence to the suspicion that a causal relationship exists between the virus and NSCLC.
At present, the scientists do not have any evidence that non-smokers have an increased risk for NSCLC. However, one area of possible future scientific inquiry could be to sample NSCLCs from non-smokers to see if they have HPV. Although it could be an aetiology in non-smokers, the investigators suspect that it causes a higher risk in smokers to develop NSCLC.
Lead study author, Dr Arash Rezazadeh, a fellow of medical oncology and haematology at the University of Louisville, stated: "In terms of HPV, our finding is pretty controversial. And this is just the beginning of the road. There is much more work to be done. But it's important to know that being infected with this virus does appear to increase lung cancer risk."
The availability of a vaccine to prevent infection with HPV is being discussed widely in the US and many other countries, but almost exclusively in relation to its utility as a way to prevent CC, which occurs only in women. The possibility that HPV could be implicated in NSCLC raises the question of whether the vaccination should be used to prevent the disease and whether men should also be vaccinated; this is something that needs to be tested. Further studies are planned to look for signs of HPV infection in the respiratory tract of NSCLC patients and to explore the possibility for using HPV infection as a screening indicator for the disease. e that this syndrome differs from that caused by irradiation and thus may represent a new class of delayed CNS degenerative damage. Previous studies have linked various CT agents, including methotrexate, cyclophosphamide, adriamycin and cisplatin, with impaired cognitive function, although results have been variable. This new work is consistent with the clinical syndrome that is commonly observed in patients and will hopefully guide future studies into the mechanisms of acute and delayed injury to the brain from clinically-relevant exposure to CT agents.
Matthew Dennis - Editor, Cancer Drug News
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