It has been announced that NEWS will have a special anniversary event in the Tokyo Dome in September this year to celebrate the group's tenth anniversary.
Oricon Style (Japanese)
Honestly it is always in question when NEWS officially debuted. Even though their first single was released in November of 2003 it was a release that was only sold in 7-11s so there are no sales figures for it. Their first major debut is with the single Kibou ~Yell~, which was released in May of 2004. But it looks like the group is side stepping that issue by instead by using the month the group was formed instead.
I am just glad the group is celebrating an anniversary as this will be the first time they will have done so. Though I would say the tenth anniversary is probably more important than the fifth anyway.
And while I would normally be worried about the group being able to fill up the Tokyo Dome since this is an event and not a concert I think Johnny's must have some idea to make sure there are not going to be a lot of empty seats for it.