Saint Agatha, who died about 251 AD, is one of the founders of the long tradition of sado-erotic iconography of the Catholic martyrs. Though actually burned to death, she is more famous for previously having her breasts chopped off, and she is usually shown at this moment (as in the illumination above), or else carrying them on a platter.
She is the patroness of wet nurses and breast cancer victims, as well as bakers (there is a long tradition of baking buns shaped like her breasts, often complete with cherry nipples.) Since her severed breasts are depicted as bell-shaped, she is the patroness of bell-founders, too. And her symbol is the scissors.
This fascination with the torture she underwent as the point of symbolic attachment was common for the early Christian saints. I suppose Agatha should be the patroness of breast torture, as well, but the church seems to be silent on this subject.