Newly published data suggest that weight loss surgery can prevent cancer. After 20 years, the landmark Swedish Obesity Study (SOS) has provided research showing that weight loss surgery is associated with a reduction in the incidence of primary cancer diagnoses. This reduction is shown especially in female-specific cancers, predominantly endometrial cancer. The findings of this study is revolutionising ongoing research into weight loss surgery.
This year, an estimated 134,000 Australians will be diagnosed with cancer. The relationship between obesity and cancer is, therefore, a vital one. In 2014, 63.4% of Australians were overweight — well over half the population. The new data from the Swedish Obesity Study suggests that the incidence of certain cancers in people with obesity can be reduced by weight loss surgery.
The Swedish Obesity Study looked specifically at the long-term effects of bariatric surgery on female-specific cancers in women with obesity. A cohort of 1420 women underwent bariatric surgery, while 1447 matched controls received conventional obesity treatment (controlled diet and exercise).
Primarily, the study confirms that conventional treatments for obesity (diet and exercise) are less effective than weight loss surgery in achieving significant, sustained weight loss. The patients in the study who underwent conventional weight loss programs experienced an initial dip in median weight, before spending the following decade heavier than they were before the study. The cohort who undertook bariatric surgery experienced faster weight loss, which they were able to sustain long-term. The data suggests that surgical weight loss is the best option for significant, rapid, and prolonged weight loss.
The study demonstrates what was previously only suggested in retrospective studies and meta-analysis — that weight loss surgery is associated with a reduction in primary cancer diagnoses. It shows that this is especially true in female-specific cancers, notably endometrial cancer. Weight loss surgery is also potentially associated with a reduction in all medical causes of death. Weight loss surgery is linked with reduced rates of multiple health risks including diabetes, stroke, heart attacks, heart rhythm disorders, gout and overall mortality.
It is possible that surgery for weight loss may be less effective in some individual cases or have more upfront or overall costs. However, it may also provide more long-term benefit and cost savings by treating the root cause of multiple health problems. Going forward, deciding on the best methods of cancer prevention will require continued investment into the biology, psychology, and epidemiology of weight gain and weight loss.
The Swedish Obesity Study will have ongoing and significant implications for the investigation of surgical weight loss in relation to cancer risk reduction. It has shed light on the direct connection between weight loss surgery and reduced incidence of cancer diagnosis, especially in female-specific cancers. This new information will inform cancer studies and treatment into the future.
The list of cancers that can be directly attributable to carrying excess weight currently stands at 13:
• Colorectal cancer
• Breast Cancer (in women after menopause)
• Ovarian cancer
• Uterine cancer
• Thyroid cancer
• Brain tumour (meningioma)
• Blood cancer (multiple myeloma)
• Kidney cancer
• Stomach cancer
• Oesophageal cancer
• Liver cancer
• Gall bladder cancer
• Pancreatic cancer