Madonna's Brother Christopher Ciccone Dead at 63

10:13 AM PT -- According to Christopher's obituary ... he died peacefully surrounded by his husband, Ray, and loved ones. The obit notes Christopher's loving spouse was faithfully by his side during the final stages of cancer that would ultimately end his life.

Another death in Madonna's family ... and this time it's her younger brother, Christopher Ciccone.

Madonna's brother died Friday in Michigan due to cancer ... his rep tells TMZ.

It's the second death in as many weeks for Madonna's family ... just last month, her stepmother Joan Ciccone died after a battle with what was described as a very aggressive cancer.

Christopher and Madonna were tied at the hip when her career was just getting started, and he famously served as one of her backup dancers.

He later graduated to being the show designer and backstage dresser for Madonna ... and he was the art director for Madge's "Blonde Ambition" world tour.

Christopher was also Madonna's tour director for "The Girlie Show" ... and he directed music videos for Tony Bennett and Dolly Parton.

Madonna and Christopher, who also enjoyed a career as an interior designer, had a public beef back in 2008, when he ripped her in his biography, "Life With My Sister Madonna," which became a New York Times best seller.

The two eventually made up and in 2012 released his own footwear line.

Christopher was 63.

RIP