Joe Biden has vowed to “cure cancer” if he is elected as president.

The Democratic hopeful made the bold pledge at a 2020 election campaign rally in Iowa.

The former vice-president, whose son died of brain cancer in 2015, told supporters on Tuesday: “I promise you if I'm elected president you’re going to see the single most important thing that changes America. We’re going to cure cancer.”

His words were met with cheers and applause at the event in the city of Ottumwa.

Improving cancer care has long been a focus of Mr Biden, whose eldest son Beau battled the disease for years before his death at the age of 46.

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During his time in Barack Obama’s administration, Mr Biden unveiled a “cancer moonshot” agenda with a stated ambition of making “a decade’s worth of advances in cancer prevention, diagnosis, and treatment, in five years”.

After leaving office in 2017, he established the non-profit Biden Cancer Initiative as “a response to the lack of a cohesive, comprehensive and timely approach to cancer prevention”.

Mr Biden’s vow to end cancer unsurprisingly raised eyebrows on social media, where some accused him of giving people "false hope".

There are more than 100 types of cancer and it is unlikely scientists could establish a single cure for them all.

Science journalist and geneticist Rob Arthur said Mr Biden's vow was a "lofty goal but a dumb thing to promise". He added: "There is not and for the foreseeable future cannot be a single ‘cure for cancer’. Cancer is an incredibly heterogeneous disease – breast cancer is not like brain cancer is not like leukaemia, and no cure would work on all of them.”

Others wanted Mr Biden to instead focus his attention on pursuing universal healthcare for Americans.

“My grandpa is dying of cancer right now and can’t live with my grandma anymore because their insurance won’t cover mixed-care living facilities,” wrote one Twitter user. ”Curing cancer is completely irrelevant if that cure is locked away within the current healthcare system.”

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But some defended Mr Biden and said his vow was "obviously personal for him" and "clearly aspirational".

Journalist Sam Stein tweeted: "There’s plenty to go after Biden about. But his pledge/promise to cure cancer doesn't strike me as one of them."