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Wait, if it's the movie I' m thinking about, the object is a suitcase with a lot of vials that contained a formula/elixir/potion-thing that the neighbor used to live longer, but there was only one dose left (which he gives to the other boy). The neighbor died because he decided to stop drinking them because he had lived enough already, yada yada. I think he said that each dose was enough to gain "one full, healthy life", or something like that.
EDIT: I think I found it! http://movies.tvguide.com/mr-rices-secret/review/134999
It's known both as 'Mr. Rice's Secret' and 'Exhuming Mr. Rice' And ohmygodDavidBowieisinitwhywasn'tIinformedofthis

Okay. So I saw this movie years ago and I've been trying to find it since. Anyway, the main character is a young boy who has a fatherly relationship with a neighbor. I'm pretty sure his actual father was out of the picture for some reason. Another kid the MC knows is a boy with cancer who is frequently ridiculed by others and held back from activities because of said illness. I specifically remember a baseball scene in which the boy with cancer is disallowed from playing. At some point the fatherly neighbor dies and the boy with cancer (I think) relapses and winds up in the hospital. But, the MC is left something in the fatherly neighbor's will. So, he goes to retrieve it and I want to say it's hidden in a birdhouse in the neighbor's yard. I can't recall what the exact object is...but it's imbued with some sort of supernatural power. The MC could use it for selfish gain, but in the end he uses it to cure the other boy's cancer.
Thanks in advance.