Shannen Doherty’s poignant message to Princess Kate has been unearthed in the wake of the actress’s death. The Charmed and Beverly Hills 90210 star died aged 53 on Saturday after a nine-year battle with cancer, her publicist confirmed. Doherty was first diagnosed with breast cancer in 2015 and was an outspoken campaigner on the disease. Following the Princess of Wales’s cancer admission, the actress sent a personal message of support to the royal. She wrote on her Instagram story back in March: “Being a public figure does not mean the public owns that person. “We ALL have the right to go throu…