Obese Women See Uterine Cancer Risk Reduced Over 70
Percent After Bariatric Surgery
May not be senior age limit for surgery or Medicare
coverage if all other criteria met
March 22, 2014 - Bariatric surgery resulting in
dramatic weight loss in formerly severely obese women reduces the risk
of uterine cancer by 71 percent and as much as 81 percent if normal
weight is maintained after surgery. There is no specific age limit for
this surgery, nor for
Medicare coverage, if all other criteria is met. Generally, age is
covered by requiring patients to have “acceptable surgical risk.” The
Mayo Clinic says the risks increase for senior citizens over age 65.
The study, indicating obesity may be a modifiable
risk factor for endometrial cancer, and bariatric surgery a viable
option for eligible patients, will presented this weekend at the Society
of Gynecologic Oncology (SGO) Annual Meeting on Women’s Cancer in Tampa,
Fla., March 22-25.
The work by researchers at the University of
California, San Diego School of Medicine and Moores Cancer Center will
be published in a special issue on gynecologic cancer prevention,
treatment and survivorship in obese women in the April edition of the
journal Gynecologic Oncology.
The findings are based on a retrospective cohort
study of 7,431,858 patients in the University HealthSystem Consortium
database, which contains information from contributing academic medical
centers in the United States and affiliated hospitals. Of this total,
103,797 patients had a history of bariatric surgery and 44,345 had a
diagnosis of uterine malignancy.
Obesity is a widespread public health problem in
the United States, with an estimated two-thirds of the U.S. adult
population considered to be overweight or obese. The condition is
strongly linked to a host of health risks, among them heart disease,
diabetes and cancer, in particular endometrial cancer.
Radiographic imaging exposes relationship between
obesity and cancer in aging population; women with more overall fat
mass, more visceral fat had a higher risk of cancer; fat puts older men
at risk even with healthy BMI
“Estimating from various studies that looked at
increasing BMI and endometrial cancer risk, a woman with a Body Mass
Index (BMI) of 40 would have approximately eight times greater risk of
endometrial cancer than someone with a BMI of 25,” said first author
Kristy Ward, MD, the senior gynecologic oncology fellow in the
Department of Reproductive Medicine at UC San Diego School of Medicine.
“This risk likely continues to go up as BMI goes
Bariatric surgery is often the last resort for
obese patients after all other non-surgical weight loss efforts have
failed. To qualify, patients must be an acceptable surgical risk and be
defined as either severely obese with a BMI of 40 or greater or have a
BMI of 35 or greater with at least one related condition: diabetes,
obstructive sleep apnea, obesity-related cardiomyopathy or heart muscle
disease or severe joint disease.
Typically, bariatric surgery involves reducing the
size of the stomach using a constrictive gastric band, removing a
portion of the stomach or resecting and re-routing the small intestines
to a small stomach pouch. In all cases, the surgery must be followed by
lifestyle changes to ensure long-term weight loss success.
About BMI Measurement
The National Heart, Lung, and Blood Institute (NHLBI) has classified
overweight people into groups based on Body Mass Index (BMI is the body
weight in kilograms divided by the body height in meters squared):
Overweight = BMI 25-29.9
Class I obesity = BMI 30.0-34.9
Class II obesity = BMI 35.0-39.9
Class III (Extreme) Obesity = BMI ≥ 40.0
By these definitions, approximately 27% of
the US population is obese and an additional 34% is overweight. Obesity
is more common in women and a BMI in the overweight range is more common
Obesity is especially common in African Americans, Native
Americans, Native Hawaiians, and some Hispanic populations.
Data for the extent of obesity in the Medicare population indicate that
in 1999-2000, 33% of men and 39% of women aged 65-74 were obese as were
20% and 25% respectively over the age of 74.
A number of biological mechanisms link obesity to
endometrial cancer. Excessive adipose or fat tissue, for example, raises
circulating levels of estrogen, which is associated with tumor creation
and metastasis. Obesity also causes chronic inflammation, boosting
insulin resistance and increased estrogen levels.
“The majority of endometrial cancers are
estrogen-driven,” said Ward. “In a normal menstruating woman, two
hormones control the endometrium (inner lining of the uterus). Estrogen
builds up the endometrium and progesterone stabilizes it.
"A woman with
excess adipose tissue has an increased level of estrogen because the fat
tissue converts steroid hormones into a form of estrogen.
“So there is too much estrogen, causing the
endometrium to build up, but not enough progesterone to stabilize it.
The endometrium continues to grow and can undergo changes into abnormal
tissue, leading to cancer.”
Bariatric surgery has been shown to reduce the
impact of these factors: hormone levels become normal; inflammation
decreases; insulin resistance drops; weight loss allows for increased
physical activity and improved overall health.
“The obesity epidemic is a complicated problem,”
she said. “Further work is needed to define the role of bariatric
surgery in cancer care and prevention, but we know that women with
endometrial cancer are more likely to die of cardiovascular causes than
they are of endometrial cancer. It’s clear that patients who are
overweight and obese should be counseled about weight loss, and referral
to a bariatric program should be considered in patients who meet
Co-authors include Angelica M. Roncancio,
University of Texas School of Public Health; Nina R. Shah, Mitzie-Ann
Davis, Cheryl C. Saenz, Michael T. McHale and Steven C. Plaxe, all of UC
San Diego Moores Cancer Center.
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