Young girls who grow taller and thinner than their sister are more likely to develop breast cancer, suggests a study.

Having signs of puberty earlier than a twin sister and a smaller waist to hip ratio at 20 also suggested an increased risk, said researchers.

The team, from the Institute of Cancer Research, is hoping that the study, which involved 400 sets of twins, will help them work out what causes breast cancer.

We were able to gain new data on the way in which factors in childhood may affect cancer risks decades later

Professor Anthony Swerdlow, Institute of Cancer Research

Researchers believe that growth patterns during various points in early life could well play a role.

The study, published in the Journal of the National Cancer Institute, found that girls who were lighter yet taller than their twin sister before the age of 10 were significantly more likely to get breast cancer later in life.

Professor Anthony Swerdlow, who led the research, said: "Comparing twins was an exceptional way to gain information about women at a young age.

"It is usually difficult to gain reliable information about possible causal factors in childhood from adults with cancer.

"We were able to gain new data on the way in which factors in childhood may affect cancer risks decades later, and, we hope, to improve our understanding of the causes of this disease."

Professor Peter Rigby, the chief executive of the Institute of Cancer Research, said: "The results of this unique study bring us a step closer to understanding the factors which can lead to the development of breast cancer."

Most common

More than 37,000 cases of breast cancer are diagnosed in the UK each year, making it the most common cancer in women.

Although there are some risk factors for the disease, such as excessive drinking, relatively little is still known about why some women get it, and some do not.

The twin study is evidence that a factor linked to age at puberty, and growth rates during childhood may be involved.

The data analysis was funded by Cancer Research UK.