A 36-26 success at Emerald Headingley saw the Tigresses complete a league double over the Rhinos as well as earn some revenge for their Challenge Cup defeat by the same team.
They were tested again as they had to recover from a slow start in which they found themselves 6-0 and 12-4 down, but came through to maintain their 100 per cent Super League record in 2019.
Char Booth opened the scoring for Leeds and although Lucy Eastwood replied Madison Laverick charged over for the hosts. Courtney Hill's second goal made it 12-4.
Cas stuck to their task and Shona Hoyle's try plus a conversion by Tara Stanley brought them to within two points.
Rhiannion Marshall then crossed against her former team to nudge the Tigresses in front.
Hill's try and conversion, however, had the rhinos 18-14 ahead at the interval.
Cas needed a big second half and got it, beginning with Maisie Lumb scoring to level the scores.
Georgia Roche put the Tigresses ahead and when Lumb crossed for her second try soon afterwards the Tigresses looked in control.
Back came Leeds with Hill collecting her second try, but Cas finished the stronger to clinch victory through further tries by Marshall and Lacey Owen and a Claire Garner conversion.
Ellie Frain scored the final points for Leeds, but it proved merely a consolation as the Tigresses had their tenth league victory of the season.