Filtered or unfiltered ground coffee? I recall other studies that correlated protection or risk of cancer with coffee to different studies with different cultur

Filtered or unfiltered ground coffee? I recall other studies that correlated protection or risk of cancer with coffee to different studies with different cultural groups, and noticed that the studies showing negative effects where all cultures that typically drank unfiltered coffee. Which, as an instant coffee drinker, left me in the dark. This study does check type of coffee, but does not differentiate filtered or unfiltered ground coffee. Not that it helps me, as I think I need another coffee before I can make sense of the instant vs. ground comparisons (first reading it seems contradictory, so I'm assuming I'm misreading or missing some nuance).