(Adds line from Kensington Palace on William's absence from memorial service in paragraph 7)
By Michael Holden and Arlene Eiras
LONDON, March 23 (Reuters) - The announcement by Kate, Britain's Princess of Wales, on Friday that she was having treatment for cancer should finally put to bed the speculation about her health, royal commentators said.
Rumours and gossip on social media, in newspapers and even some U.S. talk shows have abounded since Kate underwent abdominal surgery in January, meaning she had to take a leave of absence from royal engagements while she recovered.
"I would hope it would put the speculation to rest," royal biographer Claudia Joseph said in an interview.
"Obviously, they would hope the speculation ends but, in reality, it's social media and people are often incredibly viral and troll people left right and centre... They speculate and, and talk absolute nonsense."
Even though her office in Kensington Palace had said she was not expected to return to her public role until after Easter, which falls on March 31, Kate's absence did not stop the speculation spreading and making headlines across the globe.
This intensified after her husband, heir-to-the-throne Prince William, pulled out of attending a memorial service at Windsor Castle for his godfather, the late King Constantine of Greece, for an unspecified "personal matter".
Kensington Palace confirmed on Saturday that William's absence from the service was due to Kate's diagnosis.
When Kate apologised earlier this month after her office issued a photograph of her with her three children, which she had edited, to mark Mother's Day on March 10, the rumour mill reached fever pitch.
Even a video taken of her with William at a nearby farm shop last weekend failed to quell the conspiracy theories or demands for answers from the royals.
"The princess wanted to share this information when she and the prince felt it was right for them as a family," Kensington Palace said.
In her video message, Kate explained that she and William had been determined to protect her privacy and allow their children, Prince George, 10, Princess Charlotte, 8, and Prince Louis, 5, time to understand what was happening.
"It has been an incredibly tough couple of months for our entire family, but I’ve had a fantastic medical team who have taken great care of me, for which I am so grateful," said the princess, often still known by her maiden name Kate Middleton.
"This of course came as a huge shock, and William and I have been doing everything we can to process and manage this privately for the sake of our young family."