Doug Fister recently had surgery to remove skin cancer from his neck.

Matt Williams said players and coaches are very aware they're at risk for the disease.

"It's a big issue because you're forced to be in the sun, a lot," Williams said.

"I know (Nationals third-base coach) Bobby Henley's had similar mini-surgery ... where they take it out, and so he wears a lot of sunscreen. We put it on every day when we're out there in the daylight hours, making sure we're protected as much as possible," he said.

Fister pitched six innings Friday night in a 10-3 loss to San Francisco, ending Washington's 10-game winning streak.

Asked about what appeared to be a cut on his neck, Fister said: "I had some skin cancer removed a couple of days ago, and it had no effect tonight."