St. John’s coach Steve Lavin was host of the Women’s Coaches vs. Cancer Luncheon at the Final Four in Houston last week.

Little did most of those in attendance know that Lavin was all too familiar with the subject.

Lavin was diagnosed with prostate cancer in the fall and St. John’s announced Friday that he will begin treatment immediately.

Lavin, 46, will continue his coaching duties without interruption. April is a crucial month in recruiting and Lavin has plans in place to see several recruits.

“My family feels fortunate that through annual health exams, we detected my condition at an early stage,” Lavin said. “This past fall I didn’t want to distract our team, but with the season behind us, we are now working with medical experts and taking the proper steps to tackle this health challenge head on.”

Lavin is at least the third active Big East coach to have been diagnosed with prostate cancer. Connecticut’s Jim Calhoun and Syracuse’s Jim Boeheim have been successfully treated.

“I talked to him at length,’’ Boeheim, whose wife Juli is a driving force in Coaches vs. Cancer and helped organize the event, told The Post. “It sounds like they got it early, which is the most important factor. Steve was very positive and he has every reason to be.’’

Lavin coached St. John’s to a 21-11 record in his first season and the school’s first trip the NCAA tournament since 2002. He flew back to New York on Tuesday evening, posing for pictures with fans when his JetBlue flight landed at JFK Airport.

Boeheim said he was back coaching eight days after surgery in December 2001. Calhoun told The Post he was back coaching in 14 days.

“Jim [Boeheim] and I were a lot older when we were diagnosed than Steve,’’ said Calhoun, who rang the opening bell on Wall Street on Friday morning. “A lot of younger guys get too caught up in what they’re doing and don’t go for an annual checkup or disregard the classic symptoms.’’

“Steve can serve as a great example to younger men,’’ Calhoun added. “He went and got medical attention, which is the most important thing you can do.”