The first major trial to see if losing weight reduces the risk of cancers coming back is about to start in the US and Canada with aproximately 3,200 women being involved, with half of them losing a tenth of their body weight.
Researchers believe achieving a healthier weight could cut the risk by a fifth in breast cancer, with experts saying that they ” have known now for many years that women who are overweight or obese and are diagnosed with breast cancer have a higher risk of their cancer recurring and ultimately dying.”
This trend has been seen in more than 100 studies, and preliminary evidence showed that losing weight after diagnosis could be helpful, however that being said the idea has never been tested in a large randomised trial, which is considered the gold-standard when it comes to medical research.
The two-year trial will start recruiting overweight and obese patients, with a BMI of at least 27, in August. After their cancer therapy is completed, the women will have regular advice from dieticians to help them reduce their calorie intake to 1,200-1,500 calories per day and then eventually, they will also exercise for up to 250 minutes a week.
For every 100 women in the study who do not lose weight, they expect to see 23 have a recurrence of the tumour.
If the researchers are right, then they expect only 19 in every 100 women who did shift the pounds to have a recurrence.
It is far from clear what changes inside an obese body could be leading to cancer recurrence, but there are theories around levels of the hormone insulin or inflammation, both of which are altered with weight gain and if the idea is confirmed then it could apply to a wider range of cancers.
Prostate and colorectal cancer incidence is already known to be closely connected to waistline, however, patients with tumours such as lung or skin cancers, which are linked to carcinogens, may not benefit.
Meanwhile, a study presented at ASCO has suggested chemotherapy is less effective in obese women with breast cancer.
A team at a Turkish hospital analysed data from 295 patients to show obese women were both less likely to respond to treatment and more likely to see their cancer return.
One of the researchers in this stydy commented: “It tells us obesity is an adverse factor when it comes to chemotherapy before surgery. Obesity puts you in a more disadvantaged situation.”
SOURCES: Dana Farber Cancer Institute, BBC, American Society of Clinical Oncology
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