A study of women who had gastric sleeve or bypass surgery for obesity has found that precancerous tissue in their womb reverted to normal tissue when they lost weight.
Doctors have long known that womb cancer is caused by obesity, but until now, the effect of losing weight on precancerous changes in the womb have been poorly studied.
The research led by University of Manchester and Salford Royal scientists was funded by the NIHR Manchester Biomedical Research Centre and has been published in International Journal of Cancer.
Around 9,000 women a year are diagnosed with womb cancer, and 2,300 women die. Pre-menopausal women treated for womb cancer by surgery lose the ability to have children.
In the study, 72 women with an average BMI of over 50 – considered to be super obese – had biopsies taken from their wombs during gastric sleeve or bypass surgery.
Of the 72, four were found to have womb cancer, which was treated by hysterectomy. A further six patients had atypical endometrial hyperplasia, a precancerous condition that causes the overgrowth of cells in the womb.
Of the six women with endometrial hyperplasia, three had no signs of the condition when re-tested at eight weeks, after losing around three stone in weight.
The remaining three were treated by a Mirena coil, which releases the hormone progesterone into the womb and reverses precancerous changes. Two were shown to be free of the condition after six months.
Six monthly checks over four years revealed the precancerous tissue did not return for these five women; the last had a hysterectomy.
The remaining 62 women had normal womb tissue at the time of weight loss surgery, but it was high risk for an abnormality, with fast growing cells, cancer-causing pathways switched on and cancer-stopping pathways switched off.
By 12 months after surgery, when the women had lost around seven stone in weight, the high risk changes had reversed.
Dr Emma Crosbie, Clinical Senior Lecturer from The University of Manchester, led the study. She said: “We know that super obese women are at much higher risk of womb cancer than normal weight women.
“But we didn’t expect such a high proportion of women having treatment for their obesity to have womb cancer and pre-cancer they didn’t know about.
“Thanks to this study, we now know that helping obese women to lose weight can reverse pre-cancerous tissue changes.
“It’s clear that for super obese women, quick access to weight loss surgery has benefits beyond improving diabetes and risk of heart disease. It can also reduce womb cancer risk.
“Losing weight through dieting is also likely to be effective, but we know that dieting is very hard to do and weight lost is often re-gained.”
Obese post-menopausal women produce oestrogen from their fat stores. But as they no longer ovulate, the lack of progesterone allows the cells in the womb to grow – which increases the risk of cancer.
Inflammatory responses and Insulin production are also changed in obese women and can cause cells in the womb to grow.
“Because the reversal of precancerous changes in the womb was so quick, we think the metabolic consequences of weight loss surgery was crucial,” added Dr Crosbie.
Dr Akheel Syed is a Consultant Physician in the Department of Diabetes, Endocrinology and Obesity Medicine at Salford Royal and a co-author of the report. He said: “The number of women (and men) with clinical obesity that is damaging to health has been increasing over the years. It has been widely recognised that obesity increases the risk of health conditions such as diabetes, high blood pressure, high cholesterol, sleep apnoea and arthritis, and that losing weight can reverse this risk. In fact, weight loss surgery is the most effective strategy for reversing or improving diabetes and associated health disorders.
“What has been less widely known is that obesity increases the risk of various cancers, including cancer of the endometrium (the inner lining of the womb). In this study we were shocked to find a number of women with obesity who were having weight loss surgery had already developed symptom-less pre-cancerous or cancerous changes in the endometrium. It was, however, heartening to find that pre-cancerous changes can be reversed by massive weight loss as happens after bariatric surgery.
“Bariatric surgery is not for everyone. Changes in lifestyle, diet and behaviour remain the cornerstones of losing excess weight, and bariatric surgery will only be right for a small number of severely obese people. Women (and men) who are concerned about their weight should speak to their GP and ask to be referred to weight management programme where they can be considered for weight loss surgery if and when clinically appropriate.”