You can run a Communication Report with the Report Type set to Campaigns to check the status of all your campaigns, as well as cancel a scheduled campaign.
To run a Campaigns Communication Report:
You can check whether a campaign has been Sent, Scheduled or Cancelled in the Status column, as well as the scheduled send date in the Sent column. If a campaign is Scheduled but has not yet been sent, you can click Cancel Campaign to cancel it.
Hover over the data in the Recipients column to see a summary of the recipients:
Click on a campaign to see detailed information on recipients, recipient status, and credits used: