Rising levels of obesity in women could be causing a significant increase in cases of kidney cancer, research suggests.

New figures from Cancer Research UK show that cases of kidney cancer have increased by 22% over the last 10 years.

This rate overtakes the rise in female breast, skin and lung cancers during the same period.

The figures have been released ahead of the UK's first Kidney Cancer Awareness Week, which aims to raise the profile of a disease causing 3,000 UK deaths each year.

Possible symptoms

Blood in urine Lump in abdomen High blood pressure Recurring fevers not linked to cold or flu Swelling of ankles and legs Weight loss

Cigarette smoking is a major risk factor for kidney cancer but experts said that as there had not been a rapid rise in lung cancer, it was unlikely to be the sole explanation.

Obesity is gradually rising in Britain and more than 20% of the female population is classed as obese.

Dr Nick James, a kidney cancer expert at the Queen Elizabeth Hospital in Birmingham, said: "Being overweight causes changes in hormones in the body, particularly for women and it could be this hormone imbalance that increases the risk of kidney cancer."

Fat cells produce excess amounts of the female hormone oestrogen, which can speed up the natural process of cell division and so lead to a higher risk of a cancer cell being formed.

Lifestyle factors

Scientists at Cancer Research UK's Cancer Epidemiology Unit in Oxford are looking at data on diet and weight gain during adulthood in relation to kidney cancer.

They are also considering other lifestyle factors that may contribute to the disease and hope to announce preliminary results early next year.

Possible signs and symptoms of kidney cancer include: blood in the urine, low back pain unrelated to injury, a lump in the abdomen, fatigue, weight loss, recurrent fevers not associated with cold or flu, high blood pressure, and swelling of the ankles and legs.