"The Terry Fox Story" breaks with a longstanding TV-movie tradition, the one that maintains that anyone victimized by a fatal disease turns instantly into a chirpily inspirational Pollyanna. Terry Fox, a young Canadian athlete stricken with cancer that cost him a leg in 1977--and, finally, his life in 1981--faced crisis not only with courage but also with resentment and bitterness, according to the film. He became to friends and relatives, at times, the big pain in the neck that critically ill people can be.

And yet this relatively realistic approach to his plight makes him all the more a hero and his story uncommonly haunting. Terry Fox's triumph engenders other triumphs now: one for Home Box Office, which cofinanced "The Terry Fox Story" as the pay TV network's first original filmmaking venture, and another for Eric Fryer, the young actor in the title role giving it his proverbial all. His physically and emotionally exhaustive portrayal seems as much a great feat as a great performance.

HBO premieres the film Sunday at 8, then repeats it on Wednesday, next Saturday and Tuesday, May 31 and on additional dates in June.

To be sure, "The Terry Fox Story" has its inspirational aspirations, but the writer, Edward Hume, and the director, R.L. Thomas, tend to be a bit more subtle about them than the average TV stricken-youth movie is. Terry Fox did not in fact "conquer" cancer; it conquered him. And he never did realize his dream of making a symbolic 5,150-mile marathon run across Canada; he merely gave it a gallant try.

Fryer's portrayal conveys the suffering, the occasional insufferability and the courage. It happens that Fryer is an amputee himself; clever editing of early scenes (including an under-the-credits one-on-one basketball game) makes it appear he has two legs but, later, the stump and the prosthesis are real. Fryer's performance should be judged, however, from the neck up. It seems a complex, thoughtful and honest one.

And it has to make up for a screenplay deficient in character definition and dialogue. Fox's parents, for instance, seem barely to exist, and a promising romance with a buoyant young woman named Rika (Rosalind Chao) is curiously dropped in an unconsummated state. Since the producers admit they fictionalized Fox's story to some extent (and such stories always undergo embellishments), it hardly makes sense to introduce the relationship and then toss it away.

Where the movie risks irking HBO viewers is in the prominence of Robert Duvall's name, above the title, in the credits, since Duvall doesn't put in an appearance until 58 minutes into the 96-minute film, and then in the perfunctory role of a Canadian Cancer Society public relations man who helps Fox perk up when his spirits are flagging and prods an apparently sleepy Canadian press into attention.

Duvall does a satisfactory job, but the film seems more dependent on his name than his prowess as an actor. In fact, the part is really a little too soft for him; he looks like he's hanging around waiting for his next role. The cast also includes, as Fox's brother, Christopher Makepeace, the young avenger of "My Bodyguard," who has now grown up and lost his charm. It happens. More pivotal and strikingly on-the-level is Michael Zelniker as Fox's friend Doug, who drives the van on the trans-Canada run and endures Fox's humiliating abuse until he just can't take it any more.

Their reconciliation in a cemetery during a rest stop is a beautifully constructed insight into friendship and the peculiar stresses imposed by serious illness or handicap.

Although the real Terry Fox was quite articulate in explaining his desire to make the marathon run in interviews he gave reporters, the script is oddly vague on this point. Director Thomas also goes haywire when depicting Fox's revulsion at the pain he sees around him in a hospital during chemotherapy treatments. Thomas fails to establish that we're seeing it through Fox's point of view, so it looks like the place really is something out of an old Karloff picture. It's not advisable viewing for anybody about to undergo surgery.

There are other miscalculations--including a ridiculously inappropriate food fight--but the recoiled power of Fryer's performance accumulates; it grows stronger through every minute of the picture, and when the film is over, it lingers and can't be shaken. "The Terry Fox Story" shares a beautiful memory with the world.