Fewer teen-agers are going to the movies these days. At most times over the past decade, that sentence would have been bad news for Hollywood, which relied heavily on high schoolers to see movies three or four times and make big hits out of teen-oriented formula pictures. But surprisingly, the drop in teen attendance hasn't hurt the overall box office picture this year -- in fact, it's now clear that 1987 will set a record of about $4.2 billion in total movie grosses, breaking 1984's mark by almost $200 million. Last month was the top-grossing four-week October in motion picture history; this fall was the biggest fall ever. The year to date is up more than 12 percent from last year -- and crucially, that's not just because movie tickets cost more than they used to. So far, the year has seen a nearly 10 percent increase in the number of tickets sold -- and when you consider that increase comes at a time when teen-age attendance is declining, it means Hollywood may actually figure out that it's profitable to make movies for adults.

If more and more money is being made these days, so are more and more movies. For the third consecutive year, the number of films rated by the Motion Picture Association of America rose sharply: 466 movies were rated between Nov. 1, 1986, and Oct. 31, 1987, a 17 percent increase over the previous year and a 41 percent jump over the year before that. But don't credit the major studios with those increased totals: The figures, compiled by Daily Variety, also show that the number of films submitted by major studios has declined lately, and independent producers have taken up the slack. Major studios are now responsible for only 31 percent of the movies submitted, their lowest share in a decade -- though they still get the lion's share of box office dollars.

Mirror Images

First there was the movie. Then there was the book about the making of the movie. Now there's going to be the movie based on the book about the making of the movie. Director Carlo Lizzani's upcoming "Celluloid" will be based on a book written by Ugo Pirro about the making of Roberto Rossellini's and Sergio Amidei's neorealist classic "Open City." Scenes from the original "Open City" -- a 1946 drama about Italian resistance during the Nazi occupation of Rome -- will be used in the new film, which Lizzani says will concentrate on the personal struggles of the "Open City" directors.

While we're on the subject of new movies somehow based on old movies, Danny DeVito is the unlikely man who will turn Jean Renoir's 1931 film "La Chienne" into a modern American movie. DeVito will both direct and star in the Warner Bros. update of Renoir's film -- which has already been remade once, when Fritz Lang used it as the basis for his 1945 film "Scarlet Street." That film, starring Edward G. Robinson and Joan Bennett, was serious business; the new one, as you might guess from DeVito's involvement, will lean more toward monkey business. Production isn't due to start for almost a year.

Viet Vogue

If there's any doubt that the Vietnam war has become a completely safe and mainstream subject for moviemakers, here's the final bit of proof: Middle America's boy next door, Michael J. Fox, will play a troubled Vietnam soldier in "Casualities of War." The Paramount film will be the next project for "The Untouchables" director Brian De Palma and producer Art Linson -- and while the script for that film was written by playwright David Mamet, this time around they're turning to playwright David Rabe.