Kleybanova, the world number 28, is suffering from Hodgkin's Lymphoma.

"It's my birthday today and I want to thank all of you for the wonderful messages. I haven't written anything for a long time about why I haven't been on tour, so that's why I'm writing this today," she said in a statement.

"It's not an easy time for me right now. I've been a bit unlucky with my health. I have Hodgkin's Lymphoma, a form of cancer.

"I've been having treatment in Italy and it has been going well, but it takes lots of patience and I've had to be really strong to get through this. The good news is after I do treatment for a few more months, if I feel well, there's a chance I'll be able to play tennis again.