on our broadcast tonight, don't test for cancer. a stunning recommendation from the government about one of the most routine screening tests for a leading cancer killer, and this is already causing an uproar. the day after. a violent confrontation in the streets. a major american city nearly shut down. we are live in the streets of chicago tonight. cry for justice. two mothers, two families caught up in a tragic case. tonight, the sentence for the college student who spied on his roommate with a webcam. and ring of fire. spectacular images from one of the greatest shows on earth. spectacular images from one of the greatest shows on earth. "nightly news" begins now. captions paid for by nbc-universal television good evening.

we begin tonight with an enormous game changer in how doctors and patients should now approach prostate cancer. a government panel says doctors should no longer offer routine psa tests to healthy men because what happens next often means more harm than good. we have all seen the public campaign to raise awareness for the psa test. the test itself is an annual ritual for a lot of men who want to avoid prostate cancer or catch it early. almost a quarter million american men are diagnosed with it every year and over 28,000 die from it. but this new recommendation clearly says the possible harm of treatment way outweighs the survival benefits of early detection. it is big news. it was expected to cause an uproar and it already has. we begin here tonight with our chief science correspondent robert bazell. >> reporter: since the psa blood

test came out in 1986 it has become one of the most common cancer screening tools in america. today the task force gave the test a grade of "d," concluding it does more harm than good. >> this has been one of the most gut-wrenching aspects of medicine we deal with on a day-to-day basis. >> reporter: why not screen for the second most common cancer killer in men? the reason, many experts say, is that prostate cancer is very different from most other cancers. in one form it can be a killer, but more commonly it presents no threat to a man's life, and doctors can't tell the difference between the two forms. when the psa test, followed by a biopsy, finds cancer, doctors and their patients usually want treatment, even if it comes with possibly serious side effects. >> the public perception of cancer is that all cancer is something that is potentially life-threatening and when a patient hears the word "cancer," the first thing they want to do

is get rid of it. >> reporter: two recent large studies -- one in the u.s. and one in europe -- found either little or no survival benefit among men getting regular psa testing. but the risks of treatment can be huge. 5 in 1,000 men die within a month from the complications of surgery. at least 20% to 30% of men getting treatments end up impotent or with urinary, bowel difficulties or all three, and often permanently. with this information some men like drew harris already have decided to stop having psa tests. >> i was getting caught up in the system of overtesting. >> reporter: others like bill roth will continue. >> we are keeping a close watch on psa levels. >> reporter: in a statement today the american urological association, whose members treat prostate cancer, called the recommendations inappropriate and irresponsible and said men should have the choice to be tested. but patients do still have a choice whether they want the test.

the panel only makes recommendations. increasingly doctors are telling men if they are diagnosed with prostate cancer it might not be life-threatening and they can safely wait to see if it progresses before they decide to have treatment. but, brian, that can involve a lot of anxiety. >> as we said, this is a huge potential game changer in the world of health and science tonight. robert bazell starting us off. thank you. in chicago tonight the nato summit wrapped up without the billy club-swinging fight we saw yesterday between protesters and police in the streets of chicago. a smaller march to boeing headquarters came off without incident today. and a news conference from the president who was host here who showed off his hometown even as most residents of chicago kept a very low profile. our coverage begins tonight with

nbc's john yang who is with us from chicago's famous michigan avenue. john, good evening. >> reporter: good evening, brian. the world may have come to chicago, but today it seemed like nobody was here to welcome them. the loop was a virtual ghost town. rush hour a fraction of what it is normally. it had the feel of a sleepy, peaceful day. but yesterday? not so much. the scene was quite different just 24 hours ago as police and protesters clashed two blocks from the nato summit. after a larger peaceful march, a small group tried to crash the meeting, pushing past police lines, throwing buckets and metal barricades. protesters swung sticks, police swung batons. 45 people were arrested, half the three-day total of 90. the head of the police department praised the department's performance. >> asking them to put themselves in harm's way knowing they will get assaulted and stand there and take it? these guys were amazing. >> reporter: by contrast today's smaller march on boeing's headquarters was peaceful and at times festive.

it seemed that the only people who came to work downtown today wore blue uniforms. normally packed commuter trains were empty. >> the 5:15 came and went here and we can tell you no one got on board. >> reporter: chicagoans were urged to work from home fearing traffic and security nightmares. even the city's most powerful citizen had to alter his plans. >> nobody would let me go home. i was thinking i would be able to sleep in my own bed tonight. they said i would cause even worse traffic, so i ended up staying in a hotel. >> reporter: just another chicagoan hoping to get back to his normal routine. john yang, nbc news, chicago. this is chuck todd where the serene, calm and secure scene inside the nato summit contrasted sharply with what took place on the downtown streets. >> shut it down! >> reporter: the president brushed off the disruptions and had nothing but praise for his former white house chief of staff turned mayor. >> this is a city of big shoulders. rahm, his team, chicagoans

proved that this world class city knows how to put on a world class event. >> reporter: as for the business of the summit it was about dotting the i's and crossing the t's of the president's pledge of ending the combat mission in afghanistan by the end of 2014. today a promise to speed up the transition even further, by the summer of 2013. >> afghan forces will take the lead for combat operations next year. >> reporter: similar to the agreement president obama signed with afghan president hamid karzai three weeks ago, nato agreed to keep security forces in the country after the 2014 deadline -- just not combat troops. >> we are ready to lead a new training, advising and assistance mission. >> reporter: the one piece of unresolved business convincing pakistan to re-open a key supply line on the border of afghanistan for nato and u.s. troops. the president met briefly with president zardari about the dispute and expressed cautious optimism. the president is on his way to

joplin, missouri, where he's scheduled to give the commencement address at the graduation ceremonies for joplin high school. it is expected to be pretty emotional. it's nearly one year to the day when those deadly tornadoes hit that -- what is turning into a resilient city. >> all right. chuck todd, part of our team at the summit in chicago. chuck, thanks. overseas tonight, a horrifying attack today in a place so many of the experts have been saying for so many years represents the next big threat to the united states. our chief foreign correspondent richard engel reports on one of the most violent days in a long time in yemen. [ explosion ] >> reporter: the suicide bomber was disguised as a soldier. he tucked into a crowd at a rehearsal for a military parade in sanaa, detonated a bomb, and

killed nearly a hundred people. yemen's defense minister narrowly escaped with his life. officials say it's likely the work of al qaeda in yemen. while the u.s. has decimated al qaeda elsewhere, the militant group has grown in yemen because the country hasn't had an effective government for a year. but the arab spring finally toppled yemen's former president saleh and the new president hadi is trying to re-establish order and crack down on al qaeda. u.s. military officials tell nbc news the new president has dramatically increased government-sanctioned u.s. drone attacks in yemen and american counterterrorism training. al qaeda clearly doesn't want to be driven out. experts say al qaeda is fighting to make yemen its new safe haven. this yemeni bomb maker is one of the world's most wanted terrorists. accused by u.s. officials of plotting last month to put a so-called underwear bomb on an american-bound flight. the united states, brian, spent

the last ten years and billions of dollars and thousands of lives to dislodge al qaeda from pakistan and afghanistan. now yemen has become the latest front and today's bombing shows the group isn't leaving without a fight. brian? richard engel reporting on today's violence from cairo. richard, thanks. and now we turn to domestic presidential politics. it's happened again. sunday morning on "meet the press" it was another comment by a politician that was rather stunning at first. still tonight it has both campaigns scrambling though it's been amended because it was a member of the obama team lobbing what looked like friendly fire at the obama campaign criticizing an attack on mitt romney he was expected to defend. our report tonight from nbc's peter alexander. >> reporter: the stinging critique of the obama campaign's attack on mitt romney's experience at private equity firm bain capital came from an unlikely source -- one of president obama's own surrogates -- newark mayor cory booker on "meet the press."

>> if you look at the record at bain capital, they have done a lot to support businesses, grow businesses. this, to me -- i'm very uncomfortable with. this kind of stuff is nauseating to me on both sides. it's nauseating to the american public. enough is enough. >> reporter: just hours later responding to pressure from fellow democrats booker backtracked. >> he's talked about himself as a job creator. therefore, it is reasonable and, in fact, i encourage it for the obama campaign to examine that record. >> reporter: still, republicans quickly tried to capitalize using booker's remarks to raise money. on a day when the obama campaign hoped to highlight romney's role at bain with a new web video featuring a bankrupt company where hundreds lost jobs while bain profited. >> mitt romney didn't care about us as workers. they were looking at the mighty dollar. >> reporter: the president had to defend his campaign's focus on romney's business background arguing booker's comments weren't a distraction. >> if your main argument for how

to grow the economy is i knew how to make a lot of money for investors then you are missing what this job is about. my job is to take into account everybody, not just some. >> both sides are scrambling to imprint an image upon the voters about what the bain capital experience was good for romney or bad for other people. >> reporter: a senior adviser for the romney campaign says the bain attacks are, in his words, so old they have cobwebs. but it's clear the obama campaign plans to use them again. peter alexander, nbc news, washington. we reported here friday night on facebook's rough debut as a publically traded company after their ipo. it got worse today. in its second full day of trading facebook stock plunged to as low as $33 a share. $5 below the offer price of $38 before finishing at $34.03. it's probably not what the billionaire founder of facebook mark zuckerberg was hoping for, but it may not be the biggest

thing on his mind these days. he got married on saturday in a secret surprise wedding ceremony in his backyard. zuckerberg married his long-time girlfriend priscilla chan. the two met at harvard years ago. chan just graduated from med school and plans to be a pediatrician. facebook struggled today even as the larger markets snapped back hard from almost three straight weeks of losses. the dow was up 135 points. nasdaq surged more than 68. s&p was up almost 21. another warning tonight about young people and diabetes. a new study shows type 2 diabetes and something called prediabetes have skyrocketed among adolescents. for kids between 12 and 19, the number jumped from 9% in 2000 to 23% in 2008. one-third of adolescents in our country are now overweight or obese. we have a lot still to tell you about tonight. two mothers, two sons, two wrenching stories today about the tragedy on a college campus

that changed both families. and then a judge's controversial sentence. and, later, remembering one of the brothers who played a big part in creating the soundtrack of an entire era. ♪

very emotional day in court as a former rutgers university student learned his punishment for recording his roommate's sexual encounter on a webcam. this is a case that got the attention of the country after the humiliated college roommate, tyler clementi, took his own life by jumping off the george washington bridge. nbc's mara schiavocampo reports on the sentence and the two mothers who had their chance to speak today about this tragedy. >> reporter: dharun ravi showed little emotion in a new jersey courtroom. >> i do believe he acted out of colossal insensitivity. >> reporter: as a judge sentenced the former rutgers

university student to 30 days in jail and three years' probation for spying on his gay roommate with a webcam. in 2010 ravi streamed video of 18-year-old tyler kissing a man. using twitter, he encouraged others to watch. days after he learned of the spying incident, clementi -- an honors student and musician -- killed himself. >> i heard this jury say "guilty" 288 times. i haven't heard you apologize once. >> reporter: in today's sentencing hearing many court watchers expected the judge to give ravi the maximum ten years. >> let me go over each count. >> reporter: he was found guilty of 15 criminal charges including invasion of privacy and bias intimidation, a hate crime. before the judge's ruling clementi's heart-broken mother made an emotional plea for justice. >> i thought i knew him.

tyler and i had been very connected. so much so that i felt like a piece of me died in september 2010. >> reporter: ravi's family also appealed to the judge while the defendant openly wept. >> the media was ripping him apart. he was absolutely devastated. and broken into pieces. >> reporter: while clementi's suicide sparked a national dialogue about bullying, ravi was not charged in his death -- a fact reflected in the sentence. the judge seems to be saying let's remember what's charged here and what isn't charged here. a ten-year sentence, the judge obviously felt would be too harsh for the crimes here, but he wanted to send a message that he did take it seriously. >> reporter: after the sentencing each family consoled one another in a case the judge called a tragedy for everyone involved. mara schiavocampo, nbc news, new york. up next, why saturday may never be the same. remembering a pop icon and reliving perhaps the wildest moment of this past weekend. . [ alarm beeping, motor revving ]

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♪ which started the whole world crying ♪ [ cheers and applause ] >> the bee gees got their name from the abbreviation for brothers gibb. now just one brother remains after word from england this weekend that robin gibb has died. broin robin was the lead vocalist on so many of their songs. he also wrote many of them. as songwriters the bee gees are the only group to have number one songs in each of the last five decades. they enjoyed stratospheric success selling over 200 million albums, nine number one songs. they never fully won over some music elitists who believed disco defined the bee gees while true fans knew the difference. the brothers gibb -- robin, morris, and barry -- were born in england, lived in australia before moving back home. only barry survives now. robin gibb died of colon cancer. he was 62 years old. the man who changed the television business forever has died. eugene polley was an engineer during world war ii and worked on radar for the war department.

but then later working for zenith he came up with the first wireless tv remote control. he's the reason behind a lot of large behinds in this country but mostly electronic advances. eugene polley was 96. if you missed it over the weekend or only saw it once, what a finish at the preakness. this was the final call by track announcer larry collmus. >> it's bodemeister and i'll have another in a dramatic preakness. can i'll have another get there? here he comes. there's the wire! i'll have another did it! >> i'll have another edges out bodemeister and sets up a possible triple crown at the belmont stakes just 19 days from now. what a poignant, tear-streaked moment during the last act of the last "snl" of the season. this past saturday night, mick jagger presided over a sad farewell for kristen wiig leaving the show after seven years as the female anchor of

that cast. kristen was crying, her friends were crying. the last dance was with the boss lorne michaels. at least we get to see her in movies. up next tonight, the show was free but not everybody could see it from home.

for a brief time yesterday astronomy lovers yesterday were insanely jealous of the folks living in a narrow corridor of the country because the folks there got to see a rare and gorgeous sight when the moon slipped in front of the sun and created a ring of fire in the sky. watching from albuquerque was nbc's kristen dahlgren. >> reporter: at a time when it takes a cosmic event to get people to slow down. >> is that it? >> oh, yeah. there it is. >> whoo! >> reporter: sunday's solar eclipse was just the ticket. >> sometimes mother nature -- [ voice breaking ] i'm sorry, this is just great. >> reporter: from the philippines to vietnam, san francisco to albuquerque. >> it's pretty neat. >> reporter: a lucky few were able to see the moon pass in front of the sun in what's called an anular eclipse. the moon, at its farthest point

from the earth, doesn't completely block out the sun. >> you get this beautiful ring around the moon called the ring of fire. ♪ burn, burn, burn ♪ the ring of fire >> reporter: a rare event, it's been 18 years since one was last seen in the u.s., leaving watchers starry-eyed beneath the dark glasses, of course. >> you need special filtered glasses that makes everything else pitch black but the sun. >> reporter: for some, what may be a once in a lifetime sight left them contemplating the bigger picture. >> it just puts me in my place in the universe. >> reporter: what if you missed this one? well, you will be able to see a total eclipse in the u.s., but not until 2017. experts say that one should be visible from coast to coast. >> if anybody in north america doesn't take the trouble to see that eclipse, they're going to be deeply disappointed. >> reporter: just ask anyone who

stared mesmerized at this one, unable to turn away until the very last speck of sun slipped beneath the horizon. kristen dahlgren, nbc news, albuquerque, new mexico. >> that was the place to be yesterday. that's our broadcast on a monday night as we start off a new week. thank you for being here with us. i'm brian williams. and of course we hope to see you right back here tomorrow evening. right back here tomorrow evening. good night. good evening and thanks for joining us this monday. i'm raj mathai. >> and i'm jessica aguirre. they're supposed to be building blocks but, instead, a load of stolen legos may land a tech exec in a cellblock. >> it's a story you'll see only on nbc bay area news. kris sanchez joins us live. kris, this is a bizarre story to say the least, an executive from a high-profile company. >> reporter: it is a company you probably have heard about and perhap