According to researchers from the University of Southampton and Macmillan Cancer Support in the UK, people with colorectal cancer saw a reduction in affection, social interaction and practical and emotional support after surgery - and for up to two years afterwards, researchers said.
Those that lacked social support, such as having someone to talk to or help with practical tasks like household chores, were at a greater risk of a poorquality of life, they said.
At diagnosis, 1 in 20 (5 per cent) patients said they had little or no affection. Two years after diagnosis, this had almost trebled to 1 in 8 (13 per cent).
For those lacking emotional support, such as having someone to confide in or to ask for advice, as well as being almost three times as likely to have clinical depression, they were also twice as likely to have clinical anxiety.
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They were more than three times as likely to experience poorer wellbeing.
The research, which followed more than 1,000 people with colorectal cancer from before their surgery until five years afterwards, also showed that the odds of a patient having clinical anxiety or clinical depression are doubled if they live alone compared to those who do not.
The study highlights the needs of people affected by cancer, beyond their medical treatment, researchers said.
They need emotional and practical help and not just while they are going through treatment but for however long they need it afterwards.
Without this, people are left struggling with anxiety, depression, and poorer well-being.
"It is so important for people to have the help and support they need to manage the consequences of cancer after being diagnosed and treated," said Professor Claire Foster, from the University of Southampton.
"People can feel isolated following their treatment and those with limited social support are at greater risk of this. More needs to be done to identify and help people who are struggling in the months and years following cancer treatment," said Foster.