Where on her body a woman carries fat may affect her likelihood of developing a certain type of breast cancer, a study has found.
Apple-shaped women - who carry visceral fat around their internal organs - are more at risk of developing a deadlier form of breast cancer than those with other body shapes.
In contrast, pear-shaped women - who store fat on their hips, bottom and thighs (subcutaneous fat) - are more likely to develop a more treatable form of the disease.
Researchers from Shandong University carried out the study on 1,316 women aged between 25 and 70 from Northern and Eastern China who had recently been diagnosed with breast cancer.
They were compared with a control group of healthy women.
The pear-shaped women were more likely to have a form of the disease called ER+ (oestrogen-receptor positive) breast cancer.
According to MacMillan, about 70 per cent of breast cancers are ER+. They can be influenced by oestrogen, as the hormone can attach to proteins in cancerous cells to stimulate growth.
ER+ breast cancer responds well to treatment with hormonal therapies and patients are regularly given Tamoxifen, a drug which works by blocking oestrogen.
Apple-shaped women, however, are more likely to have ER- breast cancer.
This form of the disease can’t be treated with hormones and so patients usually go down the route of chemotherapy.
The researchers found that even if they weren’t obese, women with high waist-to-hip ratios still had a higher risk of developing ER- breast cancer.
As well as the differences in the type of breast cancer women were predisposed to based on their body shapes, the researchers found that being obese before the menopause raised breast cancer risk in these women.
The study found that women who weighed more than 62 kg, for example, had a 34 per cent increased risk of ER- breast cancer and a 21 per cent increased risk of ER+ compared to those who weighed less.
Researchers are not certain of the reason why body shape influences predisposal to breast cancer type.
“A possible reason is that subcutaneous fat is involved in oestrogen production, which may promote ER+ breast cancer,” lead researcher Dr Zhigang Yu said.
“Visceral fat is more closely related to insulin resistance and may be more likely to promote ER- breast cancer.”
Around one in eight women will develop breast cancer in their lifetime.