The young adult author, 74, wrote a blog post today (September 5) titled '!@#$% Happens', recalling the moment she received the news.
"A visit to the radiologist on June 12 for a routine ultrasound (dense breast tissue) led to a core biopsy," she wrote.
"Not that I didn't try to jump off the table and tell Dr. S I'd have the biopsy at another time because I had a really busy summer coming up. Oh, yeah--I actually did that, saying I'd discuss it with my GYN and get back to her. She convinced me, in her very quiet way, that my GYN would tell me to have the biopsy. Now.
"The biopsy report came back a few days later while I was with my GYN in her office (a long standing appointment).
"It was good that I wasn't alone and that she, who has been my doctor for seventeen years, could explain it to me. Very early. Very small. Well differentiated. All good news. But it was invasive ductal carcinoma."
Blume admitted that she was shocked by the news since there was no family history of breast cancer, while she has never smoked, doesn't drink alcohol or eat read meat, exercises daily and has been the same weight her "whole adult life".
She added that she decided to have a mastectomy and reconstruction after discussing it with her cardiologist and GNY.
"Now it's one month post surgery -- I'm still in NY and feeling stronger every day, walking a couple of miles in the park each morning and going out to early dinners with George," Blume wrote.
"Have seen movies and a couple of plays, as you know if you follow me on Twitter. I'm able to read again without falling asleep. Which doesn't mean I don't need a nap every day.
"I'm not working on my book yet (have just been given permission to type an hour at a time with arm exercises in between) but I'm thinking about getting back to it after Labor Day, kind of like starting school."
Blume also took to her Twitter today to update her followers on her recovery.
She posted: "Tweeps--thanks for all your messages. I'm feeling fine. Almost embarrassed to say how quickly I was out and about. (Not battling) Lucky!"
Blume is famous for her literary work in children and young adult fiction, writing Iggie's House; Are You There God? It's Me, Margaret; Then Again, Maybe I Won't; and It's Not the End of the World.