Answer based on context:

Hoping to keep slim playoff hopes alive, the Bengals traveled to the Louisiana Superdome for a Week 11 fight with the Saints. In the first quarter, the Bengals drew first blood as quarterback Carson Palmer completed a 41-yard touchdown pass to wide receiver Chad Johnson. The Saints would reply when quarterback Drew Brees completed a 72-yard touchdown strike to wide receiver Joe Horn. Midway through the second quarter, Cincinnati took the lead, when kicker Shayne Graham booted a 21-yard field goal. After a scoreless third quarter, New Orleans still trailed by three points. In the fourth quarter, Saints kicker John Carney tied the game with a 24-yard field goal. The Bengals offense awoke, and Palmer and Johnson connected with each other two times on 60-yard and 4-yard touchdown passes. The Bengal defense scored too, when rookie defensive back Ethan Kilmer returned a Brees interception 52 yards for a touchdown.  The Saints offense could only manage one more score , when Brees completed a 27-yard touchdown pass to wide receiver Terrance Copper. The Bengal defense then blocked the extra point attempt. Even though the Bengals were out-gained 595 yards to 385 yards, the Bengals snapped their three-game skid, and their record improved to 5-5.

What was the longest touchdown play?
72-yard