* The Toronto Stock Exchange's S&P/TSX fell 107.55 points, or 0.65 percent, to 16,435.46, the index also closed the week down 0.65 percent, snapping a two-week winning streak. * Leading the index were Cameco Corp, up 4.1 percent, Eldorado Gold Corp, up 3.5 percent, and Labrador Iron Ore Royalty Corp , higher by 3.1 percent. * Lagging shares were West Fraser Timber Co Ltd, down 8.1 percent after its quarterly results, Interfor Corp , down 6.1 percent, and Canopy Grow