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Joe Biden looked frail in his first public appearance since Hunter Biden revealed his father is in great pain as his prostate cancer has spread to other parts of his body.

Hunter said in an interview earlier this week that it has become 'really sad to watch' as his 83-year-old father continues to battle the disease.

The President was seen Saturday in his native Delaware being escorted by Secret Service as he walked to enter a BMW following mass at Saint Joseph on the Brandywine Church in Wilmington.

The former President wore a blue button down shirt underneath a light blue jacket and tan slacks.

Biden regularly attends Catholic mass in his home state, was seen speaking with fellow parishioners as he left and appeared to smile as he got into his car to head out.

Son Hunter grew emotional as he discussed his father's deteriorating condition earlier this week, describing it to BBC as very sad to watch.

'The cancer has spread, metastasized into his bones and further,' he said. 'It's very painful and it's very debilitating in many respects.'

The former president revealed his cancer diagnosis in May of last year, less than four months after he left the White House.

Hunter Biden said the diagnosis had been tough on the family.

Joe Biden looked frail in his first public appearance since Hunter Biden revealed his father is in great pain as his prostate cancer has spread to other parts of his body

The President was seen Saturday in his native Delaware being escorted by Secret Service as he walks to enter a BMW following mass at Saint Joseph on the Brandywine Church in Wilmington

Biden is seen talking with parishioners as he leaves mass

'It's really sad to watch,' Hunter said. 'The only thing that I'd say about my dad, about his health right now, is I wish he would complain more, because it's not good.

'He is the center of our family... He is our rock.'

The update comes after former First Lady Jill Biden told Today her husband would 'live with cancer the rest of his life.'

'I think if he had just been diagnosed with prostate cancer, that’s one thing because that can be cured, but the fact that it metastasized to his bones, that makes it a whole different story,' she said in June.

'So I think Joe will live with cancer till the rest of his life.'

Joe has previously undergone radiation and hormone treatment. He also had surgery to remove cancerous skin cells in September.

Hunter said his father remains 'out there,' speaking publicly about the issues that are important to him.

'He's still doing his thing,' he said. 'He so believes in this country.'

Biden walked on a sidewalk passing tombstones as he attends Mass at Saint Joseph

Biden appeared to crack a smile as he got into his BMW to head out

Son Hunter said in an interview earlier this week that its become 'really sad to watch' as his 83-year-old father continues to battle the disease

'It's really sad to watch,' Hunter said. 'The only thing that I'd say about my dad, about his health right now, is I wish he would complain more, because it's not good'

Joe Biden was the oldest man to serve as US president and his age was a source of concern for much of his four years in office.

He and his White House advisers have faced intense criticism for allegedly concealing the extent of his problems, especially after he was forced to abandon his bid for re-election after a disastrous debate with his eventual successor, President Donald Trump.

However, the former president has been open about his politics since leaving office, and will publish a memoir, Promise Me, America, after the midterm elections.

Earlier this year, Joe's inner circle were concerned that the Democrat was showing the strain of cancer treatment while still appearing publicly.

Two former Biden officials and an elected Democrat told The Washington Post in February that the former president at times appeared more fatigued in private interactions since announcing his health issues.

Another source at the time told The Post that Biden remains 'encouraged and positive about his prognosis given his positive response to treatment.'