The Accent Jobs-Willems Veranda's rider came out on top of a sprint at the end of the 183km race, ahead of Stijn Neirynck and Frederic Amorison on the winner's podium.
A group of 16 kicked the event into high gear after 8km, with Jelle Wallays, Sep Vanmarcke, Sylvain Chavanel, Frederik Veuchelen and Kevin Hulsmans among the breakaway.
Though they were caught with 50km remaining, Wallays and Vanmarcke attacked once more with no success before Wallays launched a final attack which was countered by the Omega Pharma-Quick Step team.
In the resulting bunch sprint, Caethoven surged ahead with perfect timing to give his team their first international win of the year.
“Today I felt good at the start of the race”, said Caethoven.
“I could return easily after two flat tyres, it gave me strength to believe in the victory.
”When I felt during the last five laps that the race was going to explode, I placed myself in front.
"I was always one of the first to come back to Wallays and Vanmarcke. And when at the end Freire, Leukemans and Wallays were in the attack I didn’t panic and kept faith in my speed during the sprint.
“When it was clear for Wallays that he wouldn’t be the winner of the day, Stijn Neirynck came up front. But I passed him easily in the sprint. I am looking forward to Paris-Brussels and Fourmies now."