Viruses found in lung tumours

[Guest guest]

So is this going to be another reason to justify the HPV and MMR vaccines...

?

http://www.nature.com/news/2008/080425/full/news.2008.779.html?s=news_rss

Viruses found in lung tumours

Common viruses might contribute to lung cancer.

Heidi Ledford

Researchers have found evidence that two common viruses may be lurking

behind some cases of lung cancer: human papilloma virus (HPV), already

recognized as a cause of cervical cancer, and the measles virus.

The results, which will be presented today at the European Lung Cancer

Conference in Geneva, Switzerland, are preliminary: while viruses have been

found associated with lung tumours, there is no direct evidence that the

viruses are actually causing the cancer. But the notion that a virus could

contribute to some cases of the disease is a plausible one, says

Galloway, a virologist at the Fred Hutchinson Cancer Research Center in

Seattle, Washington, who was not affiliated with the new studies.

As much as 20% of the world’s cancers have been linked to infections. In

addition to the connection between HPVs and cervical cancer, chronic

infections by hepatitis-B and -C viruses contribute to liver cancer, and the

bacterium Helicobacter pylori has been associated with stomach cancer.

In February, researchers reported viral genome sequences found in an

aggressive form of skin cancer called Merkel cell carcinoma1, although it

remains to be seen precisely how the virus contributes to skin cancer, if at

all. And some have proposed that a virus similar to the ‘mouse mammary tumor

virus’ — which causes breast cancer in mice — could also be associated with

breast cancer in humans2.

“There’s reason to believe that there are more tumours that have a viral

origin,” says Galloway. “I think there’s growing interest in this field.”

Determining whether there is an infectious cause of a cancer can have an

effect on treatment and prevention strategies. Widespread use of a vaccine

against HPV, for example, has been proposed to lower rates of cervical

cancer. Though smoking is clearly still the main cause of lung cancer,

identifying other contributors to the disease could help keep incidence down

Virus hunters

Ariad of the Soroka Medical Center in Beer Sheva, Israel, and his

colleagues began by analyzing tumours taken from 65 lung cancer patients.

They found evidence of measles virus proteins in about half of their samples

The work provides the first hint that the measles virus may contribute to

lung cancer, and follows on Ariad’s previous studies showing a possible

association between the measles virus and a cancer of the lymph tissue

called Hodgkin’s disease3.

In addition, Arash Rezazadeh of the University of Louisville in Kentucky and

his colleagues tested 23 lung cancer tumours for HPVs. In five cases, the

samples tested positive for the virus’s DNA. Others have previously shown a

possible link between the virus and lung cancer, but, as in this case, have

relied on small sample sizes.

The cancer connection

The studies leave a number of unanswered questions. Ariad speculates that

the measles virus may not be the root cause of lung cancer, but may somehow

facilitate progression of the disease once it has already started. But it is

difficult to understand how the virus would achieve this and why it would

act in the lungs, notes Galloway.

Nevertheless, the risk of lung cancer rises dramatically in patients whose

immune systems are not functioning well: a hallmark that Galloway looks for

when gauging whether a cancer may be caused by infectious agents. Although

overall cancer risk rises when the immune system fails, the link is stronger

with some cancers — including skin, lung and cervical cancer.

The studies are preliminary, but warrant additional follow-up, says Dusty

, a virologist at the Fred Hutchinson Cancer Research Center in

Seattle, Washington. “The problem is that these are associations,” he says.

“And there’s no way that you’re going to put those viruses into people to

test them.” Establishing a causal link between a virus and cancer — if there

is one — can take decades.

References

Feng, H. , Shuda, M. , Chang, Y. & , P. S. Science 319, 1096-1100

(2008).

Mok, M. T. , Lawson, J. S. , Iacopetta, B. J. & Whitaker, N. J. Int. J.

Cancer 122, 2864-2870 (2008).

Benharroch, D. Et al. Br. J. Cancer 91, 572-579 (2004).