Obesity and cancer: How bariatric surgery reduces the risk of 12 cancers

Obesity is a significant health crisis that we have known for years, causing conditions such as diabetes and heart disease. However, a connection between excess weight and cancer risk is also emerging as recent studies have revealed a shocking fact that obesity is a major risk factor that increases susceptibility to at least 12 forms of cancer. The International Agency for Research on Cancer (IARC) Working Group (2016) has also provided sufficient evidence linking 13 cancer types with obesity, showing that the absence of obesity has a preventative effect. With India observing an alarming rise in obesity among both urban and rural populations, there is a need for timely intervention for not just weight control but also for cancer prevention.

The link between obesity and cancer

Fat cells are not merely passive storage units for energy; they also function as active endocrine glands, secreting hormones such as estrogen and insulin-like growth factors (IGF-1) and inflammatory proteins. These hormones have the potential to support the growth and multiplication of cancer cells, and they can build an environment favorable to the growth of cancer. Moreover, obesity often leads to chronic inflammation, which is a known driver of tumor growth. Cancers of the breast (post-menopausal), uterus, colon, kidney, pancreas, gallbladder, liver, esophagus, and thyroid, and others have all been associated with obesity.



In women, after menopause, when the ovaries stop producing estrogen, body fat becomes the main source of this hormone. Obesity increases the production of bioavailable estrogen from both residual ovarian tissue and peripheral fat, which stimulates breast and endometrial cells and raises the risk of post-menopausal breast and endometrial cancers. Excess body fat also alters androgen metabolism, creating hormonal imbalances that encourage the development of hormone-sensitive cancers such as breast, endometrial, and prostate cancer, further strengthening the link between obesity and cancer risk.

The role of bariatric surgery

Traditional approaches like diet and exercise can feel overwhelming and exhausting for many. Bariatric surgery has emerged as a powerful and efficient tool for people with severe obesity. Gastric bypass and sleeve gastrectomy are not only cosmetic operations; they are life-changing surgeries that help decrease body weight significantly and enhance metabolic conditions. The impact of this surgery on cancer risk is significant. A recent study by the National Library of Medicine (NLM) found that patients who underwent bariatric surgery had a 25% lower risk of developing cancers. The reduction in cancer risk has been documented across multiple tumor types, such as uterine, colorectal, breast, hepatic, and pancreatic cancers.

The advantages of Bariatric Surgery

Bariatric surgery causes a significant and long-term decrease in weight that subsequently lowers the cancer-stimulating hormones and inflammatory indicators. The surgery lowers the body’s fat deposits, which in turn quiets down the harmful biological signals that would otherwise encourage cancer growth.

Here’s how the surgery helps on different levels:

• Hormonal Balance: It regulates hormones through decreased fat mass, which makes the body contain less estrogen and insulin-like growth factor (IGF-1), which is connected to cancer cell growth.
• Decreases Inflammation: The surgery helps in reducing chronic inflammation, which is a condition that may lead to tumor growth and development.
• Improves Metabolic Health: Bariatric surgeries tend to correct insulin resistance, which is a typical obesity condition, and reduce insulin levels that can contribute to cancer proliferation, as well.
• Regulates Gut Hormones: The surgery regulates the secretion of some gut hormones, which in turn can influence the appetite and metabolic processes in a positive way towards the body, but may also offer protection against cancer.

Bariatric surgery is a great step toward winning the battle against obesity related cancers. Once viewed only as a weight loss measure, this procedure can actually deliver lasting benefits that extend well beyond weight management. While surgery is helpful to obese people to reduce their weight for overall health, it offers a chance to reclaim their health while lowering their risk of a serious cancer diagnosis.


Dr. Sandeep Aggarwal, Chairman - Manipal Institute of Minimal Access, Bariatric, GI & Robotic Surgery, Manipal Hospitals Dwarka, New Delhi