LONDON (AP) — Britain’s King Charles III has been diagnosed with cancer and has begun treatment, Buckingham Palace said Monday. Less than 18 months into his reign, the 75-year-old monarch will suspend public engagements but will continue with state business, and won’t be handing over his constitutional roles as head of state.

The palace didn’t disclose what form of cancer the king has, but said it’s not related to his recent treatment for a benign prostate condition.

The palace said “a separate issue of concern was noted” during Charles’ treatment for an enlarged prostate last month, when he spent three nights in a London Hospital.

“Diagnostic tests have identified a form of cancer,” it said in a statement.