Our repair functions stop doing their job well as part of senescence. Increasing the chance and speeding up the development of tumors.

Those repair functions working better than normal is one of the hallmark signs of cancer, specifically telomerase being reactivated. Senescence is anti cancer, not pro cancer. You know those HeLa cells that are immortal? Cancer cells. Having a time limit or replication limit on cells through senescence is a great way of limiting tumors.