Singer-songwriter Ashley Monroe revealed that she is battling Waldenstrom macroglobulinemia, a rare blood cancer disorder, and that she is beginning treatment through chemotherapy. Monroe shared via Instagram on Tuesday, saying her positive mindset about her prognosis, and that she’ll begin chemotherapy on Wednesday, July 14.

Waldenstrom macroglobulinemia (referred to as “WM”), is a type of non-Hodgkin lymphoma (NHL). Between 1,000 and 1,500 people are diagnosed with it per year, or about three per million people per year. The chance of diagnosis with WM increases with age — the average age of diagnosis is 70, though Monroe is only 34 years old — and it’s more common in men than women.

Monroe is known both as a solo artist on albums such as The Blade and her latest, Rosegold, as well as her work with trio Pistol Annies, alongside Miranda Lambert and Angaleena Presley.  Monroe is married to John Danks, a former professional baseball player, with whom she shares one son, 3-year-old Dalton William Danks.