'The Office' star Jenna Fisher had triple-positive breast cancer. What is it?

Actor Jenna Fisher, best known for her role as Pam Beasley revealed on “The Office” that she was diagnosed with stage 1 triple-positive breast cancer last year, adding that she was recently “cancer free” after months of treatment.

Triple-positive breast cancer, which Fisher describes as an “aggressive” but treatable disease, makes up about 10 percent of female breast cancers, according to the nonprofit Breastcancer.org. In an Instagram post to mark Breast Cancer Awareness Month this week, Fisher said: “As anyone who's been diagnosed with cancer knows, your life changes immediately … suddenly everything in your life revolves around one thing: fighting cancer.”