By Kate Kelland

LONDON (Reuters) - Scientists have found two distinct genetic "signatures" for prostate cancer that may help doctors predict which patients have aggressive tumors, and designed experimental blood tests to read those genetic signs like barcodes.

The teams, whose work was published on Tuesday in the Lancet Oncology journal, believe tests developed from the signatures could eventually be used to tell which patients need immediate treatment.

"Prostate cancer is a very diverse disease - some people live with it for years without symptoms but for others it can be aggressive and life-threatening," said Johann de Bono, who led a study at Britain's Institute of Cancer Research. "So it's vital we develop reliable tests to tell the different types apart."

Researchers in Britain and the United States found that by reading the patterns of genes switched on and off in blood cells, they could accurately detect which advanced prostate cancer patients had the worst survival rates.

Prostate cancer is the second most common cancer in men after lung cancer. There were 899,000 new cases diagnosed worldwide in 2008, the last year for which there is full global data, according to the World Health Organisation's International Agency for Research on Cancer.

While many cases can progress quickly, spreading to other organs and becoming deadly, experts say as many as half of prostate cancers are likely to remain confined to the prostate and are unlikely to become life-threatening.

The problem has always been knowing accurately, and at an early stage, which tumors are most likely to kill.

Although tests for aggressive forms of prostate cancer already exist, experts say they are only moderately accurate.

De Bono said scientists can learn more about prostate cancers by the signs they leave in blood. This allowed his team to develop a test potentially more accurate than those available now and easier for patients than taking a biopsy, he said.

"Our test reads the pattern of genetic activity like a barcode, picking up signs that a patient is likely to have a more aggressive cancer. Doctors should then be able to adjust the treatment they give accordingly," he said in a statement.

GENE ACTIVITY

For his study, De Bono's team scanned all the genes in blood samples from 100 patients in London and Glasgow with prostate cancer. They included some already diagnosed with advanced cancer and some thought to have low-risk, early-stage cancer.

Using statistical modeling, the team divided the patients into four groups according to patterns of gene activity and, after almost two-and-a-half years, they found patients in one group had died significantly earlier than those in the others.

They pinpointed nine key active genes shared by all patients in that group, and when they tested another 70 Americans with prostate cancer, they again found these genes identified patients who survived for a shorter time - around 9 months compared to over 21 months for those without the gene pattern.

The second study by researchers in the United States identified a set of six genes linked to a more aggressive form of prostate cancer in a group of 62 patients at the Dana-Farber Cancer Institute in Boston. The signature divided patients into two groups: one with an average survival time of 7.8 months and the other with an average survival of at least 34.9 months.

The British team said their signature included several genes involved in the immune system - suggesting the immune system is suppressed in patients whose cancers spread around the body.

Commenting on the work in The Lancet Oncology, Karina Dalsgaard Sorensen at Denmark's Aarhus University Hospital, who was not involved in either study, said the findings were welcome and significant.

"These results suggest that a few selected genes in blood samples from patients...can significantly improve the prediction of outcomes," she said. (Reporting by Kate Kelland, editing by Andrew Heavens)

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  • Jerry Orbach

    The long-time "Law & Order" star announced his prostate cancer diagnosis in late 2004, at the age of 69. His manager said that he had been <a href="http://today.msnbc.msn.com/id/6765565/ns/today-entertainment/t/law-order-star-jerry-orbach-dies/#.T42htzLLzac" target="_hplink">receiving treatment since the spring</a>, and the series creator Dick Wolf told "People" that Orbach was <a href="http://www.people.com/people/article/0,,845383,00.html" target="_hplink">expected to make a full recovery</a>, but he <a href="http://gothamist.com/2004/12/29/farewell_jerry_orbach_has_died.php" target="_hplink">died just a few weeks later</a>.

  • Robert De Niro

    Little was disclosed about the actor's battle with prostate cancer, other than his 2003 diagnosis and the fact that <a href="http://articles.cnn.com/2003-10-20/entertainment/deniro.cancer_1_prostate-cancer-stan-rosenfield-full-recovery?_s=PM:SHOWBIZ" target="_hplink">doctors predicted a full recovery</a>, according to De Niro's spokesman. <a href="http://www.usatoday.com/news/health/2003-10-21-prostate-cancer-cover_x.htm" target="_hplink">His father died of cancer</a> in 1993 at the age of 71, according to <em>USA Today</em>, but De Niro was given a clean bill of health, even <a href="http://www.everydayhealth.com/prostate-cancer-pictures/famous-men-who-battled-prostate-cancer.aspx#/slide-2" target="_hplink">becoming a father for the sixth time in 2011</a>.

  • Nelson Mandela

    The former South African president was diagnosed with prostate cancer in July 2001, at the age of 83. Sixteen years earlier, he had surgery to remove some <a href="http://www.everydayhealth.com/prostate-cancer-pictures/famous-men-who-battled-prostate-cancer.aspx#/slide-11" target="_hplink">benign tumors on his prostate</a>, but a spokeswoman said the tumor was "microscopic" and would not require surgery this time. Instead, Mandela was treated with <a href="http://news.bbc.co.uk/2/hi/africa/1454103.stm" target="_hplink">seven weeks of radiation</a>.

  • Rudy Giuliani

    The former New York City mayor's father died of prostate cancer, so when he was diagnosed, he told <em>USA Today</em>, "I wished it would just go away." He said he didn't have any symptoms, but after a routine physical his doctor wanted him to see a urologist. After he was diagnosed, he opted for hormone therapy and radiation treatment and <a href="http://www.usatoday.com/news/health/spotlighthealth/2002-10-14-giuliani_x.htm" target="_hplink">urges all men over 50 to get screened</a>.

  • Joe Torre

    "In 1999 when I was first diagnosed <a href="http://www.usatoday.com/news/health/spotlighthealth/2003-06-10-torre_x.htm" target="_hplink">I had no symptoms</a>," the retired baseball manager, told <em>USA Today</em>. "When my prostate was removed, it was actually very normal looking. That's why they call it a silent killer." He was 58 at the time -- and his daughter only 3. "I wanted to be around for her," he told the <em>New York Times</em>, opting for <a href="http://www.nytimes.com/2011/05/29/sports/baseball/joe-torre-and-baseball-putting-the-focus-on-prostate-cancer.html" target="_hplink">aggressive surgery</a>. He has since spoken out in hopes of raising awareness.

  • Colin Powell

    The former Secretary of State had successful surgery in 2003 to <a href="http://articles.cnn.com/2003-12-15/us/powell.surgery_1_prostate-cancer-slow-growing-cancer-hormone-therapy?_s=PM:US" target="_hplink">remove his prostate</a> at age 66. Doctors didn't expect him to require much further care after <a href="http://www.webmd.com/prostate-cancer/news/20031215/colin-powell-undergoes-prostate-surgery" target="_hplink">two weeks of recuperation after the operation</a>.

  • John Kerry

    The senator underwent surgery in 2003 to remove his prostate, after being diagnosed with the disease that <a href="http://www.salon.com/2003/02/13/kerry_7/" target="_hplink">killed his father only three years earlier</a>. "Senator Kerry is a poster boy for early detection," his surgeon said in a statement. "We caught this very early and for that reason the prognosis couldn't be more optimistic." "It may sound strange to some of you, but I really feel very lucky as I stand here," Kerry said at a news conference, the <em>New York Times</em> reported. "And the reason I feel lucky is that <a href="http://www.nytimes.com/2003/02/12/us/kerry-to-undergo-surgery-for-prostate-cancer-today.html" target="_hplink">I'm going to be cured</a>."

  • Andrew Lloyd Weber

    In 2009, at age 61, the composer behind musicals including "The Phantom of the Opera" and "Evita" announced he was being treated for <a href="http://www.people.com/people/article/0,,20315334,00.html" target="_hplink">early stage prostate cancer</a>. In 2010, after getting a clean bill of health, Lloyd Weber, who was <a href="http://www.foxnews.com/story/0,2933,569475,00.html#ixzz1sK0TNL9f" target="_hplink">knighted in 1992</a> and named to Britain's House of Lords in 1997, spoke out in favor of prostate cancer <a href="http://www.webmd.boots.com/prostate-cancer/news/20100720/lloyd-webber-demands-prostate-cancer-screening" target="_hplink">screening for all men over 50</a>.

  • Arnold Palmer

    The golf legend was in the news recently after being hospitalized for <a href="http://www.huffingtonpost.com/2012/03/26/arnold-palmer-high-blood-pressure-hypertension-medication_n_1379959.html" target="_hplink">high blood pressure as a result of a new medication</a>, but he also made health headlines for beating prostate cancer in 1997. Deciding to have surgeons <a href="http://www.everydayhealth.com/prostate-cancer/0606/arnold-palmer-tees-up-for-prostate-cancer-awareness.aspx" target="_hplink">remove his prostate completely</a>, Palmer later told WebMD, "was probably the best thing I ever did."

  • Dennis Hopper

    The actor, best known for starring in "Easy Rider," lost his battle with prostate cancer in 2010 <a href="http://www.people.com/people/article/0,,20337801,00.html" target="_hplink">at the age of 74</a>. He <a href="http://latimesblogs.latimes.com/gossip/2010/01/dennis-hopper-divorce-prostate-cancer.html" target="_hplink">filed for divorce</a> in the middle of his illness, just as he began a round of chemotherapy, saying in a statement "I... only want to spend these difficult days surrounded by my children and close friends." He was honored with a <a href="http://articles.latimes.com/2010/may/30/local/la-me-hopper-20100530" target="_hplink">star on the Hollywood Walk of Fame</a> in March, just months before passing away.

  • Bob Dole

    The now-retired Kansas senator was diagnosed and treated for prostate cancer in 1991. He credits <a href="http://articles.chicagotribune.com/1992-05-18/news/9202140781_1_prostate-cancer-early-detection-dole" target="_hplink">early detection</a> as key to beating the disease, and afterward gave interviews, appeared in TV ads and spoke to Congress to promote communication between men and their doctors about <a href="http://www.cbsnews.com/2100-204_162-9004.html" target="_hplink">prostate-related problems</a>.

  • Harry Belafonte

    In the mid-90s, the singer was diagnosed with prostate cancer after a routine checkup. Surgeons successfully <a href="http://www.people.com/people/article/0,,20142089,00.html" target="_hplink">removed his prostate</a> and he began to speak out in hopes of raising public awareness of a disease he called "an epidemic." He focused in particular on how men in the past seemed <a href="http://articles.latimes.com/1997-04-21/news/ls-50829_1_prostate-cancer" target="_hplink">too "macho" to discuss prostate cancer</a>. He told the <em>LA Times</em>: <blockquote>The prostate is something that attacks that central part of the male body that men are very preoccupied with. Somehow, any disorder there means your life is over, you can't be a man anymore, you are now something less.</blockquote>

  • Francois Mitterand

    The former president of France was diagnosed with prostate cancer soon after he was elected in 1981, but didn't announce his illness to the public for more than 10 years, after he had <a href="http://www.nytimes.com/1996/01/10/news/10iht-mitt.t_0.html" target="_hplink">surgery in 1992</a>. Only <a href="http://www.time.com/time/magazine/article/0,9171,984025,00.html" target="_hplink">one in 10 men with his diagnosis survives</a> longer than a decade, according to "Time," but he did, thanks to a treatment regimen of hormones and other therapies, according to the <em>New York Times</em>, until his <a href="http://news.bbc.co.uk/onthisday/hi/dates/stories/january/8/newsid_4489000/4489322.stm" target="_hplink">death in 1996</a>, at 79, from the disease.

  • Eddie Montgomery

    Country musician and member of Montgomery Gentry band said in a statement that he had been <a href="http://www.people.com/people/article/0,,20443662,00.html" target="_hplink">diagnosed with prostate cancer in 2010</a>. "I will be undergoing surgery to remove the cancerous tumor in December," he said. "I will be back in January ready to rock for all the fans!" "People" reported.

  • Don Imus

    The controversial radio host announced his diagnosis of <a href="http://www.huffingtonpost.com/2009/03/16/don-imus-i-have-prostate_n_175203.html" target="_hplink">Stage 2 prostate cancer</a> on his morning show in 2009. He <a href="http://www.people.com/people/article/0,,20265826,00.html" target="_hplink">said the prognosis was positive</a>, and that he had great faith in his doctors, People.com reported. "I'll be fine. If I'm not fine, then I won't be fine. And it's not a big deal," he said.

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