Hidden risks of weight gain after breast cancer
Women are gaining more than 20 kilograms after a breast cancer diagnosis and it's increasing the chance their cancer will return and the side effects from treatment.
Two in three women reported weight gain at an average of nine kilograms after a breast cancer diagnosis, the Australian study found.
And about one-in-five women (17 per cent) added more than 20 kilograms.
Breast cancer is the most common cancer in women and this year an estimated 20,168 Australians will be diagnosed with the condition.
Researchers from NICM Health Research Institute, Western Sydney University and ICON Cancer Centre, Sydney Adventist Hospital, Wahroonga, surveyed 309 women with breast cancer around the nation.
While many women gain weight as they age the survey found women with breast cancer put on more weight, half a kilo a year more, than women without breast cancer.
The survey also found:
* The proportion of women who were overweight or obese increased from 48 per cent at time of diagnosis to 67 per cent at the time of the survey;
*The proportion of women who were obese almost doubled from 17 per cent to 32 per cent;
*The majority (69 per cent) of women gained weight in excess of women without breast cancer - an additional 2.42 kilograms over five years.
"As doctors we really need to actively think about weight, nutrition and exercise and advise about possible interventions," said study co-author and breast cancer specialist Professor Boyages.
International studies had found chemotherapy treatment was linked to weight gain study author and Western Sydney University researcher Dr Carolyn Ee said.
Being younger at diagnosis and being pre-menopausal at diagnosis were also factors that increased the likelihood of weight gain after a breast cancer diagnosis, she said.
Oncologist Dr Boyages said women undergoing breast cancer treatment were less active because they lost their hair and were worried going to the gym could expose them to infection.
Chemotherapy could cause some women in their 40s to enter menopause and this was associated with slower metabolism that could cause weight gain.
Some treatments like steroids were linked to weight gain he said.
The hormone blocking therapy Tamoxifen many women use to treat breast cancer and prevent its recurrence could be a factor in weight gain but this is unclear.
"The jury is still out on whether hormonal treatments (for breast cancer) lead to weight gain, a lot of women believe that," Dr Ee said.
There could also be psychological factors behind the weight gain.
"Women may fear weight loss means their cancer is coming back," Dr Ee said.
The psychological trauma women with breast cancer are going through means they may binge eat comfort food, Dr Boyages said.
Most of the weight the women gained was put on in the first 12-18 months after diagnosis and this presented a key window of opportunity for doctors to encourage women to exercise more, Dr Ee said.
The weight gain problem is concerning medicos because there is clear evidence weight gain increases the chance of breast cancer returning.
Women who gained 2.7 kilos had a 40 per cent increase in their risk of cancer turning.
Those who gained 7.7 kilos had a 53 per cent increased risk of their cancer returning Dr Ee said.
Dr Boyages said weight gain added to self-esteem problems, increased the risk of heart disease and other cancers and several reports suggest it may affect prognosis and also increases the risk of arm swelling (lymphoedema).
"Prescribing a healthy lifestyle is just as important as prescribing tablets," he said.
The researchers plan to investigate reasons why women are gaining weight after breast cancer, including the type of treatment they receive, and whether or not they were menopausal before diagnosis and treatment.
Breast Cancer Network Australia CEO Kirsten Pilatti says many studies highlight the importance of exercise physiologists and nutritionists for breast cancer treatment plans, however they are often an unfunded component of follow-up care.
"For many breast cancer survivors, the cost of accessing the expertise of these specialists puts them beyond their reach," Ms Pilatti said.