The star, known as the Queen of Disco, passed away in Florida, according to TMZ.
Sources say she had attempted to keep the extent of her illness from fans and was recently trying to finish up her latest album.
The news has not yet been confirmed by her spokesperson.
Summers, real name LaDonna Gaines, is best know for her string of 70s hits, including I Feel Love, Last Dance and Bad Girls.
She was a five-time Grammy Award winner and the first artist to have three consecutive double albums reach number one on the US Billboard chart.
She also charted four number-one singles in the United States within a thirteen-month period.
Summers married actor Helmuth Sommer in 1973 before giving birth to the couple’s daughter Mimi later that year.
Although the marriage crumbled in 1975, she kept an altered version of her ex’s surname to use as her stage name. She married Brooklyn Dreams musician Bruce Sudano in 1980 and the couple went on to have two daughters, Brooklyn, born in 1981 and Amanda the following year.