A cutting insert, comprising: non-identical, opposing front and back end surfaces (22, 24), each of the front and back end surfaces (22, 24) having a rectangular shape in a respective end view thereof, a peripheral side surface extending between the front and back end surfaces (22, 24), the peripheral side surface including two opposing major side surfaces (28a, 28b) and two opposing minor side surfaces (30a, 30b), a first axis intersecting the front and back end surfaces (22, 24), a first plane located between the two opposing minor side surfaces (30a, 30b), the first plane containing the first axis, a second axis perpendicular to the first plane and intersecting the two minor side surfaces (30a, 30b), a second plane located between the two opposing major side surfaces (28a, 28b), the second plane containing both the first axis and the second axis and being perpendicular to the first plane, a median plane located between the front and back end surfaces (22, 24), the median plane being perpendicular to the first axis, and at least one front major cutting edge formed at the intersection of the front end surface and the two major side surfaces (28a, 28b), wherein: the front end surface has two diagonally opposed front raised corners (R F) and two diagonally opposed front lowered corners (L F) with respect to the median plane, characterized in that the back end surface has two diagonally opposed back raised corners (R B) and two diagonally opposed back lowered corners (L B) with respect to the median plane, and in a cross-section taken in the first plane, the front end surface has a concave shape and the back end surface has a convex shape. non-identical, opposing front and back end surfaces (22, 24), each of the front and back end surfaces (22, 24) having a rectangular shape in a respective end view thereof, a peripheral side surface extending between the front and back end surfaces (22, 24), the peripheral side surface including two opposing major side surfaces (28a, 28b) and two opposing minor side surfaces (30a, 30b), a first axis intersecting the front and back end surfaces (22, 24), a first plane located between the two opposing minor side surfaces (30a, 30b), the first plane containing the first axis, a second axis perpendicular to the first plane and intersecting the two minor side surfaces (30a, 30b), a second plane located between the two opposing major side surfaces (28a, 28b), the second plane containing both the first axis and the second axis and being perpendicular to the first plane, a median plane located between the front and back end surfaces (22, 24), the median plane being perpendicular to the first axis, and at least one front major cutting edge formed at the intersection of the front end surface and the two major side surfaces (28a, 28b), wherein: the front end surface has two diagonally opposed front raised corners (R F) and two diagonally opposed front lowered corners (L F) with respect to the median plane, characterized in that the back end surface has two diagonally opposed back raised corners (R B) and two diagonally opposed back lowered corners (L B) with respect to the median plane, and in a cross-section taken in the first plane, the front end surface has a concave shape and the back end surface has a convex shape. the front end surface has two diagonally opposed front raised corners (R F) and two diagonally opposed front lowered corners (L F) with respect to the median plane, characterized in that the back end surface has two diagonally opposed back raised corners (R B) and two diagonally opposed back lowered corners (L B) with respect to the median plane, and in a cross-section taken in the first plane, the front end surface has a concave shape and the back end surface has a convex shape.