K-drama star Kim Woo-bin has been diagnosed with a rare form of cancer.

His agency, Sidus HQ, said in a statement Wednesday: "Kim Woo-bin wasn't feeling good and recently visited a doctor. We found out that he has nasopharyngeal cancer. He started receiving drug treatment and radiation therapy. Please cheer for and support him."

Kim Woo-bin is best known for his role in "The Heirs," which aired in ABS-CBN dubbed back in 2014, and " Uncontrollably Fond." He was said to have visited the Philippines in June last year.

His condition is considered rare as it is found in one in every 100,000 people in North America. It is said to be more common in China.

According to WebMD, nasopharyngeal cancer is a type of head and neck cancer, which starts the upper part of your throat, behind the nose.

Moments after the news broke, Kim Woo-bin quickly became the most talked about topic on Twitter locally, with many of his Filipino fans expressing their concern.