Preston, who received the official diagnosis on Tuesday, says she has no intentions of resigning or even taking a medical leave.
She intends to remain involved with day to day operations at the county, even participating in meetings via Skype when she's in New York City receiving treatments at Sloan-Kettering Cancer Center.
The cancer was discovered during some routine testing in advance of unrelated foot surgery.
"You know, I've faced many challenges in my life over the years. And I've always faced them head-on. I've never backed down on any fight in my life. Of course, you win some and you lose some. But, I'm here to tell you today, that this fight against cancer is the one that I intend to win," said Preston.
Preston has been a cigarette smoker for many years but is now quitting. While her doctors don't say there's a connection, she believes it is a factor and plans to use her experience as a warning for other smokers.
"You know I'm a smoker. Everybody knows I'm a smoker. I'm not denying that. Did it have an impact on this? Yes, it probably did. I'm not going to deny that, it did. I think there's a story to tell on this as we move forward," said Preston.
There's still a lot doctors don't yet know about the severity of her condition or what treatment course they'll recommend.
Preston says she would have preferred to wait to disclose her illness, but rumors and misinformation was spreading and she felt the need to set the record straight.
Her husband Paul is a prostate cancer survivor.
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