Being thinner helps beat breast cancer: Risk of disease returning rises in step with weightStudy in New York show weight loss after treatment may help decrease risk
23:05 GMT, 26 August 2012
Women who suffer from obesity when treated for breast cancer are more likely to relapse
Obese women treated for breast cancer are more likely to suffer a relapse than slimmer patients.
A study has shown for the first time that overweight women have worse outcomes from the most common form of the disease.
It found women who are obese when diagnosed have a higher chance of dying prematurely. Researchers believe the causes are hormonal.
Their results suggest that extra body fat causes hormonal changes and inflammation that may drive some cases to spread and recur, despite treatment.
Previously, it has been suggested that a greater risk of the disease returning in heavier women might be due to under-treatment with chemotherapy drugs.
It was feared they may have been receiving doses aimed at slimmer sufferers because their body size had not been taken into account.
The latest study of almost 7,000 female patients was led by Dr Joseph Sparano, of the Albert Einstein College of Medicine’s Montefiore Medical Center, in New York.
‘We found that obesity at diagnosis is associated with about a 30 per cent higher risk of recurrence and a nearly 50 per cent higher risk of death, despite optimal treatment,’ he said.
‘Treatment aimed at interfering with hormonal changes and inflammation caused by obesity may help reduce the risk of recurrence.’
The study compared the health outcomes of obese and overweight patients with others who took part in three trials sponsored by the National Cancer Institute.
Participants had to have normal heart, kidney, liver, and bone marrow function, excluding patients with other significant health problems. As a result, researchers were able to disentangle the influence of obesity from other factors.
Losing weight after diagnosis may reduce insulin which may be effective in cutting the risk of recurrence of breast cancer
The researchers found that increasing body mass index – or BMI, the relationship between weight and height – significantly increased women’s risk of cancer recurrence and early death. This was despite optimal treatment including chemotherapy and hormonal therapy.
There was a stepwise relationship between increasing BMI and poor outcomes only in women with hormone receptor-positive breast cancer. This is the most common type and affects two-thirds of sufferers.
Dr Sparano said it was ‘biologically plausible’ that increasing weight leads to greater risk of recurrence via higher insulin levels.
It was uncertain if losing weight after diagnosis could cut the risk of recurrence, but some studies suggest it reduces insulin levels, which ‘might be effective’, he added.
Catherine Priestley, clinical nurse specialist at Breast Cancer Care said: ‘We know a healthy weight is beneficial for reducing the risk of a range of health conditions.
‘So, while this study may be useful, it’s important to put this into perspective. There are a number of key features of breast cancer that will influence the risk of it coming back and each person’s predicted outlook will vary.
‘For those who have been diagnosed, there is emerging evidence that maintaining a healthy weight, as well as being physically active may help reduce the risk of the disease returning.
‘However, this can be really difficult as weight gain can be a common side-effect of treatment.’
Dr Stuart Griffiths, head of commissioned research, Breast Cancer Campaign, said: ‘The findings provide further evidence that obesity can have a detrimental effect.
‘Maintaining a healthy weight can reduce the risk of breast cancer, particularly after menopause.
‘Obesity can also affect the chances of survival for those with the most common type of breast cancer, so it is vital patients are given support on how to control their weight.’
The findings are published online in CANCER, a journal of the American Cancer Society.