In small nonstick skillet, toast cumin over medium heat, stirring constantly, 2 minutes, until fragrant; transfer to large shallow bowl.
Add corn, tomatoes, jicama, scallions, juice and salt to toasted cumin; toss to combine. Set aside.
Sprinkle chicken on all sides with Cajun seasoning. Spray large iron skillet with nonstick cooking spray; heat. Add chicken; cook over medium-high heat, turning once, 8 minutes, until browned on all sides and juices run clear when chicken is pierced with fork.
Arrange cooked chicken breasts on top of corn mixture.