Only one in five people with cancer receive any kind of formal support, with many left housebound or unable to wash or dress themselves, a charity has warned.
Macmillan Cancer Support said that with more and more people continuing to live with the disease, many have social care needs that must be recognised and dealt with.
It estimated that more than 100,000 people with the condition are constantly or often unable to wash themselves, dress or go to the toilet.
The charity said its research had also found an estimated 160,000 people are often or always left housebound due to a lack of support.
"People at all stages of the disease are lacking the care and support they desperately need, with devastating consequences for their health and dignity," the report warns.
"This lack of dignity is contributing to the huge emotional toll that cancer can inflict. People are living with constant feelings of fear, anger and isolation, not to mention depression and anxiety."
It adds that sufferers are not always aware of the practical, personal and emotional support that may already be available to them, and health and social care providers should offer clearer information to improve access to their services.
It wants the NHS, local councils and charities to work together to ensure those with cancer receive the help they need.
Lisa Grice, 55, who was diagnosed with womb cancer in 2012, said she received no support after being discharged from hospital confined to a wheelchair following a hysterectomy.
She said: "I was depressed and felt very alone, unable to wash myself or use the loo properly. I felt so hopeless that I didn't want to go for radiotherapy.
"My husband couldn't cope as he had his own physical issues. A discussion before leaving hospital about my support needs could have avoided this awful and debilitating situation."
Chief executive of Macmillan Cancer Support, Lynda Thomas, said: "There is a growing recognition that social care is often vital for people living with long-term conditions. But unfortunately people with cancer have been highlighted as a group that already have all of their needs met by the NHS, because they are thought to be purely medical in nature.
"Today's findings debunk this unfair myth. They show that people with cancer have needs which are far more widespread than we had even realised and that sadly the health and social care systems are too often failing to provide people with basic support.
"Macmillan is urgently calling on the NHS and local authorities to recognise that people with cancer do have social care needs and they desperately need more support. Macmillan is keen to work with these organisations to help people reclaim their lives - and dignity - from cancer."
A Department of Health spokeswoman said: "The NHS is rising to the challenge on cancer - dealing with 700,000 more admissions this parliament compared to the last, while at the same time survival rates have risen to record levels.
"In the last cancer patient experience survey most patients said they were given enough care and support - our £5.3 billion Better Care Fund will join up health and social care, reducing unnecessary visits to hospital and helping more people to live at home."
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