A cancer doctor has started a campaign for the Democratic nomination for the congressional seat now held by Republican Dan Burton, who is facing four prominent challengers for the GOP nomination.

Nasser Hanna of Fishers says he'll formally announce his candidacy for the 5th District seat next week during stops in Noblesville, Indianapolis and Marion. Hanna is an oncologist specializing in the treatment of lung cancer at Indiana University's Simon Cancer Center in Indianapolis.

The district is heavily Republican and Burton has typically won since 1982 with two-thirds or more of the vote. But Burton narrowly won the 2008 GOP primary, and two current or former state legislators and two former congressional candidates have organized campaigns for the May primary.