Young people would rather use social media or talk online to people they do not know than have a conversation face to face, research has suggested.
Those aged 18 to 24 are around 20 times more likely to never speak to their neighbours, than those aged 55 and over, a survey carried out on behalf of Cancer Research UK found.
Experts said the research showed an increasing generational divide between how millennials and baby boomers prefer to communicate.
The charity said that while social media can be helpful in building up contacts, studies show that young adults with high social media usage can feel more socially isolated than those who use it less.
Nearly half (44%) of 18 to 24-year-olds said they felt more comfortable using social media, messaging apps and online to talk to people they did not know, the research found.
Just two in five (37%) of 18 to 24-year-olds said they would be more comfortable speaking in person, compared to two-thirds (67%) of over 55s.
And more than a quarter (27%) of the younger age group said they have never spoken to someone they did not know on public transport – more than five times the rate of those aged 55 and over (5%).
Nearly half (47%) saying they prefer to listen to music on their headphones instead.
The charity is also encouraging people across the country to come together in person to unite against cancer, and wear Unity Band wristbands to show their support.
Dr Rebecca Beeken, a behavioural scientist working on cancer prevention at the University of Leeds, said: “This research shows an increasing generational divide between how millennials and baby boomers prefer to communicate.
“While it is no surprise that young people are embracing new ways to chat, and there are supportive communities online, it is important they don’t lose the art of talking to the people around them.
“Social isolation can be associated with poor health and poorer health behaviours, and we know social support is important for adopting healthy lifestyle changes.
“These changes can play an important role in helping to prevent cancer. That’s why Cancer Research UK is encouraging people to unite with each other for World Cancer Day and get together to wear a Unity Band to help fund life-saving research.”
A report released by the Jo Cox Loneliness Commission last month found that loneliness is as harmful to health as obesity or smoking 15 cigarettes a day.
The online survey for Cancer Research UK saw YouGov sample 2,163 adults, of which 252 were aged between 18 and 24.