Councilman Albus Brooks, who represents Denver’s District 9, announced Tuesday morning that he has cancer and will take a medical leave of absence for four to six weeks.

In a Facebook post, he said a chiropractor found a mass after he sought help with some muscle stiffness after running the Bolder Boulder.

Brooks said he has a good prognosis, and his doctors expect to be able to remove the tumor entirely with surgery.

Brooks gave no public sign that anything was wrong at Monday’s Denver City Council meeting as he oversaw several public hearings on land use issues affecting his district, including the creation of two new zoning districts for Arapahoe Square.

But he grew quiet and seemed contemplative at one point as he recalled taking over then-District 8 in 2011 after the death of Carla Madison from colon cancer and reading her extensive notes on ongoing issues.

“I learned a lot from Carla,” he said.