The public hearing on a proposed $80-million cancer center in Danbury has been closed by the Planning Commission.  During their meeting last week, members set the date for a vote on the application as July 21st.  The state Office of Health Strategy is still considering Danbury Proton's bid to create Connecticut’s first cancer center to use proton therapy.  The single-story 16,000-square-foot facility would sit on 3-acres on Wooster Heights Road.  The technology aims to kill tumors with a minimum of damage to healthy tissue.  The specialized treatment center would add 300 trips a day.