Summary: The death rate from cancer has dropping slowly but surely each year (at about %1.5-%16 rate). This last reported year was largest single percentage drop in that process - 2%. That could also be phrased as 98% of the deaths happened the previous year (2016) also happening that year (2017). Half-full, half-empty, etc.

So it's a blip but an encouraging blip. At the same time, the headline makes this sound much more extreme and excite.