Apple-shaped women are at risk of a deadlier form of breast cancer (and those who store fat on their thighs, hips and buttocks are prone to a more treatable form of the disease)

Apple-shaped women are at risk of developing a deadlier form of breast cancer, a new study suggests. But those who have a pear-shaped figure, with fat stored on their thighs, hips and buttocks, are prone to a more treatable form of the disease.

For years, scientists have warned of the dangers of obesity due to evidence of its role in triggering breast cancer among other health risks. But the Chinese study shows the link between obesity and this form of the disease to be more complex than previously thought.

They discovered women with a higher BMI, which measured subcutaneous fat, were more likely to have ER+ (oestrogen-receptor positive) breast cancer. This form of the disease can be influenced by oestrogen, as the hormone can attach to proteins in cancerous cells to stimulate growth. Patients are often given Tamoxifen, a drug that costs 6p a day and which work by blocking oestrogen, which is known to stimulate the formation of tumour cells.

In contrast, those with a high waist-to-hip ratio, showing belly fat, were more likely to have ER- (oestrogen-receptor negative) breast cancer. This form of the disease can't be tackled with hormone blocking drugs, and have to go down traditional chemotherapy routes. The greater risk of developing ER- breast cancer for women with a high waist-to-hip ratio existed even if they weren't obese, Shandong University scientists noted.

Lead researcher Dr Zhigang Yu said: 'A possible reason is that subcutaneous fat is involved in estrogen production, which may promote ER+ breast cancer. 'Visceral fat is more closely related to insulin resistance and may be more likely to promote ER- breast cancer.' The researchers said that clinicians should assess ER- risk by assessing a woman's body shape before prescribing Tamoxifen, which is often given to those at high risk.

Experts stressed the findings, published in The Oncologist, were important as breast cancer is becoming a 'pandemic'. Around one in eight women will develop breast cancer in their lifetime and the illness is becoming increasingly prevalent as the population ages. There were 55,222 new cases recorded in the UK in 2014 and 11,433 deaths. In the US, 252,710 are expected to receive a diagnosis this year. Around 40,000 will die.

Researchers recruited 1,316 women who were newly diagnosed with breast cancer for the study. They were compared to a control group. Body measurements were taken, alongside details of their form of cancer - whether it was ER+ or ER- breast cancer.