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She helped a generation of young tweens find their way through puberty and adolescence in classic books like "Are You There God? It's Me, Margaret " and "Superfudge," and now author Judy Blume is revealing her own cancer diagnosis to help others realize it could happen to them too.

In an entry posted on her blog today, Blume, 74, says she was diagnosed with invasive ductal carcinoma earlier this summer after undergoing a routine ultrasound as she was preparing to depart for a five-week stay in Italy.

READ MORE: Are You There Twitter?, It's Me, Judy

"As I've told my friends who've also been treated for breast cancer, I've joined The Club - not one I wanted to join or even thought I would ever be joining - but here I am. I'm part of this Sisterhood of the Traveling Breast Cells (apologies to Ann Brashares). Medical diagnoses can leave you feeling alone and scared. When it comes to breast cancer you're not alone, and scary though it is, there's a network of amazing women to help you through it," she writes.

Instead of writing in Italy, Blume, who also revealed she was diagnosed with cervical cancer 17 years ago and had a subsequent hysterectomy, found herself preparing for surgery.

"Wait - me?," she writes in the post, titled "!@#$% Happens." "There's no breast cancer in my family (recent extensive genetic testing shows no genetic connection). I haven't eaten red meat in more than 30 years. I've never smoked, I exercise every day, forget alcohol - it's bad for my reflux - I've been the same weight my whole adult life. How is this possible? Well, guess what - it's possible."

Blume, whose adult and children books have sold more than 80 million copies and hit the New York Times bestseller lists, underwent a mastectomy July 30, six weeks after she first received the diagnosis.

In describing her decision to opt for a mastectomy and reconstruction, Blume weaved perhaps her most famous book character, Margaret, into the discussion.

"I have small breasts (a la Margaret Simon)," Blume writes. "Like Margaret I used to think bigger was better. But my dense, small breasts aged well. They stayed perky while other body parts sagged. I'd become quite fond of them. Still, the idea of mastectomy wasn't a difficult emotional decision for me… I was focused on having as little anesthesia as possible, and the quickest recuperation."

Today, one month post-surgery, Blume says she is at home in New York City and "feeling stronger every day," returning to normal activities like walking, going to dinner with her husband, George, and venturing out to movies and plays.

Blume is also optimistic about her future in writing, something her millions of fans will love.

"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," she writes.