South Korea’s largest food and entertainment conglomerateCJ Group said Thursday that its incumbent chairman has undergone a surgery to remove a cancerous tumor from his lung, raising fresh concerns of potential instability in the group’s top management.

CJ Group chairman Sohn Kyung-shik, 76, received surgery at Seoul National University Hospital in central Seoul on Tuesday, and is now in a stable condition and recovering, CJ Group spokeswoman Yoon Yeo-jin said.

Doctors had discovered the malignant tumor in May and decided this week to conduct the surgery to prevent the tumor from spreading to the rest of Sohn’s body, according to Yoon.

“Chairman Sohn is not in a serious condition as the cancer is in its early stages and has not spread to other parts of his body. He is fast recovering and will likely return to his post in a few days,” she said, dismissing concerns of a prolonged vacuum in the group’s leadership.

Sohn is the uncle of Lee Jay-hyun, the ailing CJ Group co-chairman who was indicted in August 2013 over charges of embezzlement, breach of trust and tax evasion. Since then, Sohn has been leading CJ Group in place of Lee, who remains away from his post due to his deteriorating health and unfulfilled jail term.

Since his indictment, Lee Jay-hyun, who is currently hospitalized, has had his jail term suspended several times due to surgery and poor health.

Lee, 56, has been suffering from Charcot Marie Tooth Disease, an inherited neurological disorder, CJ Group said. In August 2013, he received a kidney transplant after postponing his imprisonment.

Despite CJ’s efforts to lighten the ruling, the Seoul High Court sentenced Lee Jay-hyun to 2 1/2 years in jail and a fine of 25.2 billion won ($21.6 million) in December last year. He has since appealed the verdict to the Supreme Court, which has yet to make a decision.

Given his health conditions, the court has pushed back Lee’s imprisonment to July 23. With just weeks left, CJ Group “plans to request the court to delay his imprisonment once again before the deadline” as the chairman continues to suffer from many health problems, according to Yoon.

Other members of CJ Group’s founding Lee family are said to be suffering from severe illnesses as well, preventing them from overseeing the group’s businesses. Lee Jay-hyun’s older sister Lee Mie-kyung, the 58-year-old vice chairwoman of CJ Group, is reportedly in poor health and residing in the U.S. to receive treatment.

CJ Group’s chief advisor and Lee Jay-hyun’s mother Sohn Bok-nam, 84, suffered a stroke, a cerebral infarction, in December 2015 and remains unconscious.

Lee Chae-wook, the chief executive officer of CJ Group, is reportedly receiving treatment for a lung-related disease as well. He is not a member of the group’s founding family.

By Sohn Ji-young (jys@heraldcorp.com)