Trial to investigate link between weight, fitness and cancer recurrence
Scientists to test hypothesis that a weight loss programme for breast cancer patients after medical treatment lowers risk of disease returning
A large trial is being launched this summer to establish whether diet and exercise regimes should be prescribed by doctors for women who have had breast cancer in the same way that they prescribe drugs, to prevent the disease returning and potentially save lives.
Women who are overweight or obese have a higher risk of breast cancer. But accumulating evidence suggests that becoming fitter and losing some pounds after a diagnosis could cut the chances of a recurrence and even lower the risk of death.
A number of small studies looking at the benefits of exercise and weight loss on cancer by researchers at Yale University in the US are being presented at the American Society of Clinical Oncology meeting (ASCO) in Chicago.
Prof Melinda Irwin, associate director at Yale Cancer Center and professor of epidemiology at the Yale School of Public Health, said: We found a strong connection between exercise after diagnosis and mortality afterwards.
Most interestingly, it showed the impact on changes in activity on mortality even if youve never been active before taking regular exercise seemed to show a great impact.
The studies followed women who went on a diet and started taking exercise after cancer but they did not randomly assign women to a fitness regime or not, so it is possible those who did well were also better at taking their drug treatment.
But I am in the camp that says this association is causal and reversible and thats what these latest studies indicate, said Irwin.
They show that losing weight and taking up exercise have a significant effect on the biomarkers of cancer. They are showing that its causal that by changing activity or weight loss it could improve your prognosis. This is crucial.
Among these small studies is one involving 144 women with ovarian cancer who did 150 minutes of aerobic exercise each week for six months. Early results show they had a drop in the levels of certain hormones linked with the growth of tumours, compared with women who did not exercise.
Another study of 221 women with breast cancer found those who lost weight on a diet had a drop in the levels of a protein that fuels tumour growth.
The trial of 3,200 women in Canada and the US, which will start on 1 August, will seek to answer the questions raised by these small studies. It will be a randomised controlled trial, allocating the participants into two groups to compare their progress. One group will be put on a diet and exercise regime, supervised and supported by a fitness coach who will speak to them regularly on the phone. The other group will be given advice on healthy eating and activity.
We have known for many years that women who are overweight or obese and diagnosed with breast cancer have a higher risk of their cancer recurring and ultimately dying from breast cancer as compared to leaner women with similarly sized tumours at a similar stage with similar treatment, said Dr Jennifer Ligibel, of the Dana-Farber Cancer Institute in Boston,who is leading the breast cancer.
We dont really know why that is the case but its been seen over and over now in more than a hundred studies.
There is some preliminary evidence that helping women to lose weight after theyve been diagnosed with breast cancer could be helpful. Thats never been tested in the setting of a large-scale randomised trial.
So we are very interested in testing the hypothesis that if you take women who are overweight or obese, complete their standard treatment for breast cancer and you have them take part in a weight loss programme that that would lower their risk of breast cancer recurrence.
The aim is for women to lose 10% of their starting weight, through a diet of 1,200 to 1,500 calories and bout 150 minutes of activity a week over first six months. Then for women who attain that try to get them more up to 220 to 250 minutes if we can because thats really the level thats been shown to help keep weight off after youve lost it, she said.
They can choose any activity they like and she expects walking to be popular. Its a very accessible form of exercise. It doesnt cost anything. You just need a pair of shoes. My patients always ask me whats the best form of physical activity and honestly the answer is the one that youll do, she said.
The results of the trial will not be known for several years, but if it is successful, she hopes to see doctors prescribing exercise and weight loss diets as well as drugs where necessary. This would be the first time that a lifestyle programme was really something that was standardly prescribed as part of cancer treatment, she said.