Manu came off the bench in the 57th minute of Tonga's Rugby World Cup opener against England, which the latter won 35-3 in Sapporo on Sunday.
Last year, the former Highlanders captain had surgery to remove an abnormal growth, then endured months of chemotherapy, before receiving the all-clear to return earlier this year.
Manu was scheduled to play for Tonga in the Pacific Nations Cup, but a pectoral injury kept him out of action for that tournament and the 92-7 hammering from the All Blacks.
