Legendary rapper Guru (born Keith Elam), 43, of seminal hip-hop duo Gang Starr, died on Monday (April 19) of cancer-related causes—about two months after undergoing surgery following a heart attack.

According to a press release issued by Solar—the Boston-bred MC’s longtime business partner, music collaborator and friend—Guru had been quietly suffering from cancer for a long period of time.

Before passing, Guru addressed his fans one last time in a letter provided by Solar. “I, Guru, am writing this letter to my fans, friends and loved ones around the world,” he wrote. “I have had a long battle with cancer and have succumbed to the disease. I have suffered with this illness for over a year. I have exhausted all medical options.”