Sadly, cure cancer is a 7th level spell. Better keep leveling if you want to save Grandma.

We have a new guide to 5th level cleric spells for you all.

With 5th level spells, clerics gain the ability to raise the dead, one of the best crowd control spells in the game, and an effective aoe damage spell. A cleric at this point of ability is not a offensive juggernaut, but has reached the point where almost any negative effective that can be cast upon party members can be removed. The only ability missing is the ability to remove feeblemind, which comes with the heal spell at later levels.

See the full guide at Ten Ton Hammer's DDO site.