Britain’s King Charles III is thanking those who have sent messages of support in his battle with cancer and on Saturday made his first public appearance since being Buckingham Palace earlier this month made public his diagnosed with the disease.

“I would like to express my most heartfelt thanks for the many messages of support and good wishes I have received in recent days,” Charles said in a statement. “As all those who have been affected by cancer will know, such kind thoughts are the greatest comfort and encouragement,” Charles said.

Charles, 75, had been diagnosed with a form of cancer less than 18 months into his reign.

In his first public outing since the diagnosis, Charles attended church on Sunday.

The announcement of the diagnosis Monday followed Charles having spent three nights in hospital last month for a benign enlarged prostate.