Complex sentence: On July 20 the singer announced via Twitter that she was again cancer free, while on October 1,2013 to coincide with Breast Cancer Awareness Month, Anastacia informed the media that she had undergone a double mastectomy.
Split into simpler sentences: On July 20 the singer announced via Twitter that she was again cancer free. While on the 1st of October 2013 to coincide with Breast Cancer Awareness Month, Anastacia informed the media that she had undergone a double mastectomy.