Kathy Bates' doctor helped her to turn her breast cancer diagnosis into something positive.

The 'American Horror Story' actress, who underwent a double mastectomy three years ago, was angry when she developed lymphedema - a build-up of soft body tissues - after having the surgery, but she then decided to become an ambassador for the Lymphatic Education & Research Network [LE&RN].

The 67-year-old star explained to PEOPLE magazine: ''About three years ago I discovered I had breast cancer and underwent a double mastectomy. After the surgery, I developed lymphedema. I have a very mild case, but I have to wear compression garments from time to time. My doctor helped me turn my anger about having this debilitating disease into something positive - she told me about the LE&RN, and I've become an ambassador.

''Now when I attend social events wearing my [compression] sleeves, I feel less self-conscious. I want people to ask me about it. Lymphedema affects up to 10 million Americans. Hopefully more people will come out of the shadows and talk about it.''

Kathy previously admitted she was looking forward to getting back to work after her diagnosis in 2012.

She at the time: ''My doctors have assured me I'm going to be around for a long time. I'm looking forward to getting back to work doing what I love.''