Fasting every day may protect against breast cancer, research suggests.
A study found allowing obese mice to only eat within a strict eight-hour window ‘dramatically’ reduced their risk of the disease.
This was even true among rodents injected with breast-cancer cells or those which were genetically at-risk of the disease.
The time of eating was also found to be more important than what was consumed, despite a high-fat diet and obesity both being linked to a greater risk of breast cancer.
Restricting when we eat may lower our insulin levels, with excessive amounts of the hormone previously associated with the disease.
Fasting every day may protect against breast cancer, research suggests (stock)
The research was carried out by the University of California, San Diego, and led by Dr Manasi Das, a postdoctoral scholar of medicine in the school of health sciences.
Around one in eight women in the US and UK will develop breast cancer at some point in their lives, statistics reveal.
The scientists set out to determine how a woman’s metabolic health may influence her risk.
Metabolic syndrome is the medical term for a combination of diabetes, high blood pressure and obesity, according to the NHS.
To better understand how metabolic health relates to our cancer odds, the researchers carried out three experiments on mice.
All the rodents had no ovaries to mimic a post-menopausal state.
Menopause itself does not cause cancer, however, our risk of developing the disease rises with age, according to the MD Anderson Cancer Center.
Postmenopausal women are therefore more at risk because they are older.
In the first experiment, mice were made obese by consuming a 60 per cent fat diet for ten weeks.
They were then divided into two groups – one with 24-hour access to food and the other with eight-hour access at nighttime.
Due to mice being nocturnal, nighttime is when they are most active.
Both these groups of obese rodents were then compared against lean mice with access to a low-fat diet for 24 hours a day.
All the animals were injected with breast-cancer cells three weeks into their eating plans.
In the second study, mice that were genetically modified to develop breast cancer were divided into two groups – one with constant access to a high-fat diet and the other with restricted access.
For the third and final study, mice on a low-fat diet were fitted with either an insulin pump or a saline control.
These were compared against rodents on a fatty eating plan that had their insulin levels reduced by having the drug diazoxide – which blocks the hormone’s release – added to their feed.
Mice in all three of the studies underwent ultrasound scans to determine any tumours.
The overall results revealed time-restricted eating had a ‘dramatic’ effect on the rodents’ risk of breast cancer.
Only eating within a strict window delayed the development of tumours.
It also reduced the growth of cancerous cells in the obese mice on a high-fat diet to be the same as that of lean rodents.
According to Breast Cancer Now, a woman’s risk of developing breast cancer increases if she is overweight or obese after the menopause.
The mice implanted with an insulin pump also experienced faster tumour growth, while those fed diazoxide were less at risk.
Full results will be presented on Saturday at ENDO 2019, the Endocrine Society’s annual meeting, in New Orleans.
‘The results suggest the anti-tumor effect of time-restricted eating is at least partially due to lowering levels of insulin, suggesting this intervention may be effective in breast cancer prevention and therapy,’ Dr Das said.
‘Exploring the ability of time-restricted eating to prevent breast cancer could provide an inexpensive but effective strategy to prevent cancer impacting a wide range of patients and represents a groundbreaking advance in breast cancer research.’
Insulin triggers cells – including cancerous ones – to grow, previous research has suggested.
And other hormones related to insulin may also be higher among the obese, which could trigger breast cancer, scientists have previously said.
WHAT IS BREAST CANCER, HOW MANY PEOPLE DOES IT STRIKE AND WHAT ARE THE SYMPTOMS?
Breast cancer is one of the most common cancers in the world. Each year in the UK there are more than 55,000 new cases, and the disease claims the lives of 11,500 women. In the US, it strikes 266,000 each year and kills 40,000. But what causes it and how can it be treated?
What is breast cancer?
Breast cancer develops from a cancerous cell which develops in the lining of a duct or lobule in one of the breasts.
When the breast cancer has spread into surrounding breast tissue it is called an ‘invasive’ breast cancer. Some people are diagnosed with ‘carcinoma in situ’, where no cancer cells have grown beyond the duct or lobule.
Most cases develop in women over the age of 50 but younger women are sometimes affected. Breast cancer can develop in men though this is rare.
The cancerous cells are graded from stage one, which means a slow growth, up to stage four, which is the most aggressive.
What causes breast cancer?
A cancerous tumour starts from one abnormal cell. The exact reason why a cell becomes cancerous is unclear. It is thought that something damages or alters certain genes in the cell. This makes the cell abnormal and multiply ‘out of control’.
Although breast cancer can develop for no apparent reason, there are some risk factors that can increase the chance of developing breast cancer, such as genetics.
What are the symptoms of breast cancer?
The usual first symptom is a painless lump in the breast, although most breast lumps are not cancerous and are fluid filled cysts, which are benign.
The first place that breast cancer usually spreads to is the lymph nodes in the armpit. If this occurs you will develop a swelling or lump in an armpit.
How is breast cancer diagnosed?
- Initial assessment: A doctor examines the breasts and armpits. They may do tests such as a mammography, a special x-ray of the breast tissue which can indicate the possibility of tumours.
- Biopsy: A biopsy is when a small sample of tissue is removed from a part of the body. The sample is then examined under the microscope to look for abnormal cells. The sample can confirm or rule out cancer.
If you are confirmed to have breast cancer, further tests may be needed to assess if it has spread. For example, blood tests, an ultrasound scan of the liver or a chest x-ray.
How is breast cancer treated?
Treatment options which may be considered include surgery, chemotherapy, radiotherapy and hormone treatment. Often a combination of two or more of these treatments are used.
- Surgery: Breast-conserving surgery or the removal of the affected breast depending on the size of the tumour.
- Radiotherapy: A treatment which uses high energy beams of radiation focussed on cancerous tissue. This kills cancer cells, or stops cancer cells from multiplying. It is mainly used in addition to surgery.
- Chemotherapy: A treatment of cancer by using anti-cancer drugs which kill cancer cells, or stop them from multiplying
- Hormone treatments: Some types of breast cancer are affected by the ‘female’ hormone oestrogen, which can stimulate the cancer cells to divide and multiply. Treatments which reduce the level of these hormones, or prevent them from working, are commonly used in people with breast cancer.
How successful is treatment?
The outlook is best in those who are diagnosed when the cancer is still small, and has not spread. Surgical removal of a tumour in an early stage may then give a good chance of cure.
The routine mammography offered to women between the ages of 50 and 70 mean more breast cancers are being diagnosed and treated at an early stage.
For more information visit breastcancercare.org.uk or www.cancerhelp.org.uk