Dolly Parton Cause of Death Revealed

Dolly Parton died following a brief battle with cancer ... TMZ has confirmed.

Parton’s reps said in a statement to TMZ ... she was surrounded by loved ones at Vanderbilt-Ingram Cancer Center in Nashville when she died.

Her reps say Dolly spent her life bringing "joy, laughter, hope and integrity" to everything she touched, and point to her enormous generosity through Imagination Library and her support of medical research.

They add her unconditional love for others was the driving force behind the lasting impact she leaves behind.

The icon died Tuesday at 80 ... and the news hit especially hard because, as TMZ reported, her death was sudden even for loved ones who knew she'd been dealing with health issues.

Sources told us Dolly's family and friends knew she was sick ... but still believed she'd pull through, making her death a shock to those closest to her.

Dolly had been hospitalized in Nashville for four days before her death after battling a number of health problems in recent months.

Celebrities quickly paid tribute to Dolly ... sharing emotional messages and memories of the legend -- including two of her closest famous friends, Jane Fonda and Reba McEntire.

Jane -- Dolly's "9 to 5" costar and longtime friend -- remembered her as funny, generous, and completely one of a kind.

Reba also mourned Dolly ... saying there would "never ever be another" and sharing memories from their decades-long friendship.

Of course, Dolly leaves behind one hell of a legacy ... she spent more than 6 decades in showbiz ... becoming one of the biggest names country music has ever produced with classics like "Jolene," "9 to 5" and "I Will Always Love You."

And her reach went way beyond music ... Dolly became a movie star, businesswoman, and beloved philanthropist, with her Imagination Library giving books to millions of children.

From humble beginnings in Tennessee to country music royalty ... Dolly became a true American icon.