(ShareCast News) - Assura was working to reassure shareholders about the health of the company, and its chief executive, on Friday.The FTSE 250 firm had revealed on 9 February that Graham Roberts had been diagnosed with cancer.On Friday, the board confirmed that Roberts had now taken a leave of absence as he received further treatment.Assura said the chairman, Simon Laffin, had become executive chairman in the interim, adn was working closely with the executive team.