While she worked at Shaw Brothers, her popularity grew and she became one of the first stakeholders in the up and coming TV broadcast station TVB. In 1967, Shum's stardom took off with the popular television variety show Enjoy Yourself Tonight. She first sang in the Cantopop group the Four Golden Flowers. Later, she played a Shanghai woman in the 1970s. She also sang as the partner of Roman Tam from 1971 to 1973.
By August 1972 she was sufficiently regarded to be one of the first Chinese to ceremonially ride through the Cross-Harbour Tunnel on its opening day. TVB general manager Stephen Chan has said that there was no substitute for Lydia Shum, and that every person who worked with her professionally eventually became well known in Hong Kong. Her openness to appearing in sport bikinis and ballet costumes despite her weight earned her respect in image-conscious Hong Kong.
Shum has been established mainly as a comic and dramatic actress but is not limited to films in those genres. Kung fu fans will recognize her from her role as Yuen Cheung-Yan's dominating wife in the film Drunken Tai Chi. She also appeared as Richard Ng's wife in the all-star comedy Millionaire's Express, as well as a major role in It's a Mad Mad World. Her 1997 film Fitness Tour is utilized her weight for its plot.
She took a leave from her movie career in 1997, and hosted a talk show in Hong Kong, along with numerous telethons and variety shows on TVB. She returned to films in 2004 with the comedy In-Laws Outlaws.
Due to the hurried circumstances of their marriage and Shum's size, there was insufficient time to prepare for a wedding gown, so Shum wore a Chinese cheongsam instead. Shum later said in a 2006 interview in Hong Kong that one of her greatest regrets was to not have put on a wedding gown for her marriage.
Lydia Shum was the sister of fashion designer Alfred Sung.
Prior to a cholecystectomy done in 2002, she suffered bile duct inflammation in 1978 and again in 1989. On September 22 2006, the inflammation recurred. Four days later, it had complicated her liver and she went into a coma until October 1. Once again, on January 29 2007, she entered the operating room to remove a liver tumor which weighed 2.7 kg. On March 8 2007, the tumor was found to be growing so she had another cholecystectomy.
On November 1 2006, a 24-year-old Indonesian domestic helper, Triyuliarti Yuyun, was convicted of violating the Hospital Authority Ordinance and sentenced to four weeks in jail. Yuyun entered a ward at the Queen Mary Hospital (QMH) on October 1 2006 where Shum had been receiving treatment, and attempted to take photographs of Shum. Later, it was confirmed that Yuyun was a domestic helper to one of the employees of the local magazine, East Week, but she had not been authorized to take photographs of Shum. East Week's senior management did not approve of the action and offered an apology to Shum. Magistrate Colin Mackintosh determined that Yuyun's actions were premeditated and done for financial gain and that the serious infringement of the patient's privacy warranted a custodial sentence. On that occasion, Shum was discharged from the hospital in July 2007.
On October 11 2007, Shum collapsed at home with pleural effusion, and was rushed to Queen Elizabeth Hospital (QE) for emergency treatment. Later that day, Shum was transferred to QMH. She was discharged from that hospital on October 16 2007.
Shum was admitted to the intensive care ward at QMH on January 22, 2008 and checked out four days later. Shum's mother died in Canada, while Shum was in the hospital. She was once again admitted to the intensive care ward at QMH on February 2 2008, where her condition worsened. On February 19, at 3am, her family decided that Shum's life support should be withdrawn. It was decided that her breathing apparatus would be removed and that her family spend time with her by her bedside. Shum died at 8:38 a.m. (local time) on February 19 2008.
Prior to her death, she was known to be suffering from liver cancer which she had fought for two years. As part of the treatment for her illness, she underwent chemotherapy and several rounds of kidney dialysis treatment.
On February 24 2008, escorted by her daughter Joyce, Shum's body was taken by a Cathay Pacific passenger flight from Hong Kong to Vancouver, Canada. On February 27, Shum was buried at Burnaby's Forest Lawn Memorial Park in a private ceremony. Video footage of the funeral was played at a memorial event at the Hong Kong Coliseum on March 2.