Judy Blume, author of many popular teen fiction books such as "Are You There God? It's Me, Margaret," announced on her blog Wednesday that she was diagnosed with breast cancer this summer and has already undergone treatment.

Blume, 74, revealed on her blog that the breast cancer diagnosis came as a complete shock.

"Wait -- me? There's no breast cancer in my family," she wrote. "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."

Six weeks after Blume received the results of her biopsy, the author underwent treatment on July 30. Her cardiologist and gynecologist cautioned her against radiation treatment, leaving a mastectomy and reconstruction as her best option.

Even in the face of cancer, Blume retained her trademark sense of humor. "I have small breasts (a la Margaret Simon)," she wrote. "A-cups? The breast surgeon asked at our first meeting. She nailed it. I told her the exercises didn't work for me. Not sure she got my attempt at a joke."

At the same time, Blume approached the situation pragmatically, writing, "the idea of mastectomy wasn't a difficult emotional decision for me. Maybe because my breasts have never defined my sexuality."

One month after the surgery, Blume said she is living healthily in New York, "feeling stronger every day, walking a couple of miles in the park each morning and going out to early dinners with George [her husband George Cooper]."

Due to her surgery, Blume has had difficulty resuming work on her latest book but hopes to be back writing soon. "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," she wrote, "but I'm thinking about getting back to it after Labor Day, kind of like starting school."

Blume's blog post ended with her encouraging all women to be regularly checked for breast cancer, stating that she was lucky hers was caught at a very early stage.

Blume's books became famous for their frankness in dealing with tough subjects for a young readership. As a result, "Tales of a Fourth Grade Nothing," "Tiger Eyes," and "Are You There God? It's Me, Margaret" all became huge hits in the young adult fiction world. Blume's books earned her many adult fans as well.

In April, Blume told the Los Angeles Times, "When I started to write there was no such thing as YA books. I was never trying to write for teenagers. Nobody ever said to me that books were off-limits. Reading was good, this is a positive thing, Judy likes to read, this is good."