Although no one will ever admit it, this week’s announcement that Gov. Jerry Brown is being treated for prostate cancer puts California’s top job very much in play.

Sure, that’s a terrible thing to say, especially when the governor’s doctor is saying the cancer was caught early and that the chances of a full recovery are very, very good.

But politics is all about timing and when a 74-year-old governor is found to have a serious illness, California politicians can be forgiven for thinking, even just for a moment, “What if …?”

And don’t think Brown doesn’t know that. When he had a common and generally harmless skin cancer removed from his nose last year, he vanished from public view until the bandage was removed and he was looking and feeling better.

For an aging officeholder, any illness, however slight, can be potentially fatal to your political well-being.

Back in 2000, Dianne Feinstein broke her leg and severed a tendon in a fall at her Aspen, Colorado, vacation home. It was a nasty injury that required a long and rugged rehab.

Suddenly, the senator began looking every one of her 67 years. And just as quickly, rumors began spreading about how the end could be near for the former San Francisco mayor’s political career.

Well, that didn’t happen and last month Feinstein, now a healthy and robust 79, was elected to a new six-year-term in the Senate. Still, it’s a good bet that the senator was mighty happy she didn’t need to share a debate stage with Elizabeth Emken, her 49-year-old GOP opponent.

With Brown, Feinstein and 72-year-old Sen. Barbara Boxer holding the state’s three top elective offices, there are plenty of younger pols wondering when it will be their turn to reach for the top rung on the ladder. Democrats like Lt. Gov. Gavin Newsom, Attorney General Kamala Harris, Controller John Chiang and Los Angeles Mayor Antonio Villaraigosa are just a few of those who look in the mirror each morning and see a governor or a senator staring back.

Even before the cancer diagnosis, there was plenty of speculation that Brown might be content to be a one-more-term governor, especially if he felt he had the state moving back in the right direction. True or not, that possibility has been enough to keep plenty of Democrats poised to move into full campaign mode at a moment’s notice.

The governor’s illness, serious or not, does nothing to lower that readiness level.

Brown knows any political leverage he has with the Legislature will disappear the instant he says he’s not running for re-election. And even if he hasn’t decided whether to put up with the aggravation of another campaign in 2014, Brown still has plenty he wants to get done in the next two years.

That’s one reason he and his team are downplaying his bout with cancer, talking about his “short course” of radiation therapy, his “excellent” prognosis and, of course, his plan to continue to work a full schedule. His spokesman even went out of his way to say that Brown was doing chin-ups in his Sacramento office with Sacramento Mayor – and former NBA star — Kevin Johnson last week.

“Healthy as a horse,” was the unspoken message to all the state’s gubernatorial hopefuls. “Move along, nothing to see here.”

John Wildermuth is a longtime writer on California politics.