 It was not until doctors achieved greater understanding of the circulatory system in the 17th century that they could link breast cancer's spread to the lymph nodes in the armpit.The French surgeon Jean Louis Petit (1674–1750) performed total mastectomies which included removing the axillary lymph nodes, as he recognized that this reduced recurrence.Petit's work was built on by another French surgeon, Bernard Peyrilhe (1737–1804), who additionally removed the pectoral muscle underlying the breast, as he judged that this greatly improved the prognosis.