Time Warner Cable chairman-CEO Glenn Britt has had a recurrence of cancer but will continue to run the cable operator through the end of the year, he announced in a memo to employees Tuesday.

In July, Time Warner Cable announced that Britt will retire at the end of 2013. Rob Marcus, currently president and COO, will take over the top job at the start of next year.

In the memo, Britt said he recently underwent tests to determine the cause of an ongoing issue with his voice since mid-summer. A few weeks ago, “the doctors determined that I have cancer,” he wrote. The exec is a cancer survivor, having recovered from melanoma five years ago.

“I have begun treatment and am getting terrific care,” Britt wrote in the memo. “I feel good and am optimistic about my prognosis. I have no intention of letting this cancer slow me down, and will continue to work until my retirement at the end of the year.”

Britt said the transition to Marcus’ taking over as CEO was well under way before his diagnosis. “The transition has been seamless so far and is nearly complete,” he wrote. “Your well wishes mean the world to me, so thank you for all you have done and will continue to do to support me as I fight this illness.”