This also happened to me. I don't recall my surgeon mentioning it as a possibility, but I had done some research and found out that it was a possibility, so I wasn't completely surprised. I had invasive lobular carcinoma, stage 1a. This type of cancer (ILC) is impossible to see visually until it gets pretty large (often stage 3). The surgeon doesn't know that it has been completely removed until the pathology results come back in about a week. My ILC was detected on mammogram due to unusual pattern of calcifications, so I was "lucky" it was found early. Since mine is pleomorphic (an unusual sub-type) the margins must be clear of "in situ" lobular carcinoma (LCIS). The surgeon I went to for a second opinion explained that this is a kind of "baby cancer" which is likely to develop into cancer if not removed. You might want to ask whether you have ductal cancer (85% of breast cancers) or lobular (about 10%, but the second most common kind). If you have lobular, it is not surprising what happened. I'm sorry you had to go through this.

Hopefully the radiation team will give you more info on moisturizing after treatment, but in a nutshell it's 4x per day (lotion-free during treatment). Diligence in this regard will save you all kinds of skin damage and pain. I used Udderly Smooth not only because it worked, but it is a light, fluffy consistency that goes on easily (no friction on tender skin), non-greasy and is much less expensive than a good lotion. After 33 treatments, it was nearly impossible to tell the treated breast from the untreated. Good luck.

Glad it went well! Drink lots of fluids, rest up! You got this! I had a few nodes removed the first surgery, the second was not as much cutting , they used the same incision. Rest up and kick its butt!