The Black Cats are on a 12-match winless run and are just three points clear of the drop zone.
“When you have gone months without a victory, you know that you are in a relegation battle,” Cana told the Sunderland Echo.
“The table is tight and the other clubs around us have picked up points. But we are not thinking too much about a relegation battle – we are concentrating on getting a win and having a strong finish to the season.
“I think the team we have has enough quality to be higher up the table but over the last two-and-a-half months we have had so many problems with injuries or players coming back from injury and not being at their best level.
“In the Premier League you cannot get away with that.
“What we have to do is to keep the spirit high and try to pick up as many points as we can.”