mesothelioma

When Sue Kernaghan underwent chemotherapy for aggressive breast cancer, she'd been warned severe side-effects were par for the course.

This is because the toxic drugs that are used to attack the cancer cells also affect the healthy cells, causing temporary problems such as hair loss, dry mouth, sickness, lethargy and forgetfulness.

Indeed, during her seven months of chemotherapy, Sue suffered all these symptoms.

But what she had not anticipated was to be still experiencing dry mouth and, more significantly, cognitive problems six years after her treatment.

'After my chemotherapy, I was in a state of shock because I was trying to cope and couldn't. Then it dawned on me that I wasn't getting my cognitive skills back,' says Sue, 56, a single mother, from Ellesmere Port, Cheshire.

'I would forget things I shouldn't forget, such as conversations I'd had with people, even when they reminded me. I couldn't multi-task in the way I used to.

'People said my loss of memory was my age or changes in hormones, but it is more than that. I never got my brain back.

'Recently, I went to watch a football match and two days later I wasn't able to remember the score. I really have to think about things to recall them and because I can't always remember things, it makes me worried and anxious.'

As a result of her cognitive problems, Sue, who has a 27-year-old daughter, had to give up her senior managerial position in the NHS.

'My job required lots of multi-tasking and I couldn't do it any more. They were very good and tried to rehabilitate me, but I just couldn't cope and I applied for another job,' she says.

Sue is one of many thousands who suffer from chemobrain: an impairment to their memory, concentration and the way they think caused by chemotherapy.

This can occur as a short-term problem - Kylie Minogue complained at the time of her treatment for breast cancer that chemo had made her forget everything - but for many patients it never improves.

For years, doctors and scientists have concentrated their work on trying to improve cancer survival rates, with much success.

Figures published last month by Cancer Research UK, for instance, showed the number of women dying of breast cancer fell to less than 12,000 in 2007 - the lowest number since records began in 1971.

Indeed, as a result of medical advances, there are two million cancer survivors in Britain.

But as a result of their treatment - surgery, chemotherapy and/or radiotherapy - around a third have long-term side effects. These can include incontinence, tiredness and chemobrain, says Macmillan Cancer Support.

Yet despite the huge numbers involved, 'not enough attention has been given to the effects cancer treatment has on the daily lives of patients', says Professor Jessica Corner, chief clinician at the charity.

'There has been a tendency for health professionals not to give patients enough detail and information about how they will be affected by cancer treatment,' says Professor Corner.

'This means they haven't been prepared for it, nor are they able to plan around it.'

That is now changing, and cancer charities provide patient information about the possibility of long-term chemobrain before they start their treatment.

Last year, the Department of Health also launched the National Cancer Survivorship Initiative to look at these issues.

But our understanding about chemobrain (also known as chemo fog) is still in its infancy.

Breast cancer patients were the first to report long-term chemobrain, and so far most of the research - around 100 published medical papers worldwide - have concentrated on these women.

According to Cancer Research UK, up to 50 per cent of breast cancer patients who undergo chemotherapy suffer from chemobrain. While for most patients, symptoms go or really improve within a year of ending treatment, research published in the Journal Of Clinical Oncology found brain dysfunction continued for up to ten years in some breast cancer patients.

Swedish research published last year found that men undergoing chemotherapy for testicular cancer also experienced a range of thinking problems.

About one in three who had chemotherapy between four and 21 years previously had language problems, compared with one in six men who hadn't had any chemotherapy.

One theory is that chemotherapy affects the brain's ability to grow cells.

This could explain why chemobrain is more likely in older patients, whose brains are also affected by age-related deterioration, and those receiving more intensive treatment.

But, as Professor Corner explains: 'It is difficult to predict who it is going to affect. Some people sail through the treatment; others say they experience long-term problems.'

According to Cancer Research UK, taking aspirin - which maintains or increases blood flow to the brain cells and so increases their oxygen supply - may be a way of preventing or treating chemobrain in the short term. Another possibility is stimulants given to people with chronic fatigue syndrome.

Long-term, the charity recommends keeping your mind active by doing puzzles, exercising and eating healthily, making lists and keeping life simple.

However, some experts are not convinced that chemotherapy itself causes cognitive problems - long-term or short-term.

Professor Karol Sikora, former clinical director of cancer services at London's Hammersmith Hospital and now medical director of the independent organisation CancerPartnersUK, says there is still a question as to whether the condition is real.

'It is the same issue as with ME (chronic fatigue syndrome). Is this condition real?' he says.