Breast cancer awareness month: What impact obesity has on breast cancer

Over 600 million adults across the world are said to be living with obesity, which constitutes approximately 13% of the world’s population. The negative impact of obesity is well elicited on metabolic diseases like diabetes, high blood pressure and heart disease.

However, obesity is now also implicated as a risk factor for multiple cancers like that of the food-pipe, stomach thyroid, pancreas, large intestine, prostate, gallbladder, uterus, ovary, breast and multiple myeloma.

Breast cancer is one of the commonest cancers in women and the second leading cause of death from cancer in women. Obesity has emerged as an important risk factor for developing breast cancer in women especially after menopause. Obesity is also said to be associated with worse disease outcomes for women in all ages, hence it is very important to understand the impact of obesity on breast cancer.

Obesity impacts breast cancer genesis, diagnosis and treatment in multiple ways:

• Fat is a metabolically active tissue and is considered as an endocrine organ by itself. Women with obesity have higher fat levels which can lead to excess estrogen production. This has been implicated as a possible mechanism for poorer outcomes in breast cancer.
• Women with large and heavy breasts are less likely to be able to feel smaller lumps in the breast during self-breast examination.
• Women with obesity are less likely to have regular screening mammography. This can be attributed to lack of compliance or sometimes hesitation due to a negative body image associated with obesity.
• There is a higher level of fear of death, low self-esteem and embarrassment in women with obesity and many times this can prevent them from seeking care from the healthcare system and lead to a delay in diagnosis.
• Healthcare providers may sometimes reflect negative perceptions and preconceived biases against women with obesity and this may have an adverse effect on decision making.
• Patients with obesity have a higher risk of complications after anesthesia and surgery for cancer. Many a times they also have other co-morbidities like diabetes, high blood pressure, breathing issues, heart disease etc, thus putting them in the high-risk category. The operative times are also longer.
• Women with obesity are poorer candidates for reconstructive surgery after removal of breast cancer. They are 2 times more prone to develop surgical complications after reconstructive surgery. They are also said to experience more dissatisfaction from the esthetic results of surgery.
• Patients with large breasts may need higher dose of radiotherapy which may have a greater adverse impact on the heart and lungs.
• Lymphoedema is a dreaded complication after breast cancer surgery and is seen to be more common in women with obesity as compared to normal women.
• Appropriate dosing of chemotherapy is challenging in patients with obesity. Underdosing may have an impact on the overall disease outcome and lead to poorer disease-free survival in these patients.

Women with obesity and breast cancer present unique challenges. Obesity is associated with delayed diagnosis and difficulties with treatment. Efficacy of treatment is also lower as compared to normal weight women with breast cancer.

Impact of weight loss on breast cancer:

In a recent study that looked at 180,885 women over a period of ten years, it was observed that losing even a small amount of weight was associated with a significantly decreased risk of developing breast cancer. Women who lost 2 to 4.5 kg had a 13% lower risk of breast cancer. Women who lost 9 kg or more had a 26% lower risk of developing breast cancer.

However, getting to a healthy weight or losing weight is not an easy task for most people. Most of the times patients are advised to lose weight but are not guided about “how” to lose weight.

Obesity must be treated according to the disease severity in order to effectively reduce the adverse impact of the disease. Patients in overweight category and those with grade 1 obesity (BMI 27.5 to 32.5 Kg/m2) may benefit from a supervised diet and lifestyle management, drug therapy or endoscopic therapies for weight loss.

However, with increasing weight and BMI, these therapies alone may not work effectively. Patients with grade 3 obesity (BMI ≥ 37.5 Kg/m2) and those with grade 2 obesity (BMI ≥ 32.5 Kg/m2) with associated co-morbidities may benefit more from metabolic/bariatric surgery.

According to a recent study that reviewed the data of 1,670,035 patients with a BMI ≥ 30 Kg/m2, bariatric/metabolic surgery cut the overall risk of developing cancers linked to obesity by 20 percent. In another study of 88,625 patients grade 3 obesity it was shown that bariatric/metabolic surgery was associated with a 33 percent lesser risk of developing any type of cancer, and a 40 percent reduced risk of being diagnosed with a cancer associated with obesity.

Weight loss has significant favourable implications for prevention of all types of cancers and especially breast cancer. There is compelling evidence now that weight loss induced by bariatric/metabolic surgery also plays an important role in cancer prevention.

In this day and age where chronic lifestyle diseases are a leading cause for death, both patients and doctors must be unbiased and open to considering appropriate treatment options when it comes to management of obesity.

The author is a Bariatric and laparoscopic surgeon, Saifee, Apollo Spectra, Namaha and Currae Hospitals, Mumbai

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