Breast Cancer and Obesity
Melita Dodaj
Felician College

Abstract

Breast cancer continues to be a major cause of cancer deaths in women. Based on recent studies the prevalence of overweight and obesity in almost every country has been increased. Estrogen is manly responsible for the elevated risk for breast cancer in obese women. Also the other tow mediators that are held responsible are adipokine leptin and insulin -like growth factor-I, IGF-I. Experiments demonstrated a mitogenic role of these three mediator an cell proliferation. The data in the article shows a stimulative effect of substances produce by the adipose tissue on the breast cancer. Body weight cell specific proliferation suggests that obesity related adipokines and mediators enhance cell proliferation and increase the risk for breast cancer. A couple guidelines and recommendations that help to prevent obesity are physical activity and diets. Obesity is associated with poorer survival in women with breast cancer, regardless of menopausal status. The purpose of this study was to determine if the associations of obesity with breast-cancer specific, all cause, and non-breast cancer mortality differ from between Hispanic and non-Hispanic white women with breast cancer. Also some other recent studies have shown that elevated BMI may be associated with breast cancer treatment-related lymphedema.

Introduction Cancer is a disease of the cells in the body, fundamentally genetic. Cancer is defined as “ a malignant form of tumors which are tissue masses that arise through mutations in the genes that govern cell growth and division”. Tumors occur when specific changes or mutations, occur in genes. The frequency and consequences of these genetic changes can also be altered by environmental factors. There are many different kinds of cancers. Cancer can develop in almost any organ or tissue, such as the lung, colon, breast, skin, bones, or nerve tissue. It is caused by the uncontrolled growth of abnormal cells in the body. Our daily lifestyle is one of the risk factors why malignant cells grow. Drinking excess alcohol, excessive sunlight exposure and obesity are some of the bad habits we practice. Obesity is a disorder of the body characterized by the accumulation of excess body fat. It is thought that more than 20 cancer are linked in a very strong way on being overweight or obese, particularly cancers on the colon and rectum, pancreas, kidney and also including breast cancer on which I will be focused on in particular in this research paper.

Pathophysiology Being overweight can affect the risk of cancer because fat tissues in the body produce hormones and growth factors that can affect the way our cells work.
Breast cancer is the most common cancer in women, with higher death rates in many countries and is considered responsible for most common cancer deaths. Based on recent studies the prevalence of overweight and obesity in almost every country has been increased . Therefore results have indicated that the hormone estrogen is mainly responsible for the high risk for breast cancer in obese women, mostly because adipose tissue is a major source of estrogen production. Those studies have shown an increase in breast cancer regarding the risk in postmenopausal women, (because after menopause the ovaries stop producing hormone) specifying the central role of estrogen in regulating cellular differentiation, apoptosis induction and proliferation. Although, obesity is also connected with the secretion elevation of other mediators such as the adipokine leptin and insulin-like growth factor-I, IGF-I, also some cytokines such as TNF- α and IL-6. As we know leptin is a protein produced by fatty tissue and functions as a stimulant for the hypothalamus to regulate body weight and peripheral energy. Circulating levels of free and unbound leptin are strongly connected to body fat content and are significantly elevated in obese women compared to normal weight humans. Also it does stimulate the proliferation of various types such as monocytes, vascular endothelium, glomerular endothelial cells, respiratory epithelium and adrenal cells. The third factor, insulin-like growth factor-I which is produced by the liver and acts as an essential factor for regular growth processes by increasing protein synthesis, stimulates cell proliferation and by inhibit apoptosis. The article reports that an association in between adiposity and high levels of free IGF-I and elevated serum concentration of IGF-I have been linked to risk of premenopausal breast cancer. Blood levels of the IGF-I associated insulin-like growth factor binding protein 1 are reduced in obesity, which leads to an enhanced bioavailability of IGF-I. Having sad that IGF-I promotes cellular proliferation and inhibits apoptosis in many tissue types giving a high contribution to tumorigenesis. In addition they did several animal studies which have shown reduced tumor growth after inactivation of the IGF-I receptor or after some manipulation to reduce circulating or tissue IGF-I levels.
Prevention
Several guidelines and recommendation including physical activity an nutrition have been published to help health care professionals to manage and prevent obesity or overweight patients, which after may lead to different cancers. Also, those recommendations are valuable even after a cancer in the past , meaning that patients should keep them in a good shape to avoid a recurrence of secondary cancers. Generally, the article through National Heart, Lung and Blood Institute (NHLBI) recommends that all women with a BMI of 30 or greater or women with a BMI of 25-29.9 or a waist circumference of 88cm (35 inches) and two risk factors should definitely attempt to loose weight. A risk factor is considered the presence of excess fat in the abdomen that is out of proportion to the total body fat, which is usually measured by waist circumference. The article highlights that changing dietary and especially physical activity is a healthy way to avoid obesity, and to moderate weight loss should be the focus of treatment, meanwhile the goal should be long-lasting weight loss over a prolonged period. Statistic An estimated 11,000 to 18,000 breast cancer deaths per year in U.S. women under the 50 years of age could be prevented if women maintained a body mass index (BMI) of <25kg/m^2 throughout their adult lives. Several recent prospective studies have examined the relationship between obesity and breast cancer-specific mortality and reported relative risks ranging from 1.45 to 1.57. The purpose of this analyses was to determine if obesity is associated with breast cancer-specific, al cause, and non-breast cancer mortality, and specially this article explains the differ by Hispanic versus non-Hispanic white women. Mean follow-up time was about 13 years. There were a total of 215 deaths, 106 Hispanic versus 109 non-Hispanic white women, and 129 of these invasive cases were considered breast cancer-specific deaths. Twenty-eight percent of Hispanics compared to 16% of non-Hispanic white women were obese . in between the women who were overweight at age 18, more Hispanic were obese at the time of interview, 16% compared to 2% of non- Hispanic white women. Approximately 27 % of Hispanic and 11% NHW women who were obese had a history of type 2 dibetes. Hispanic women consumed more calories per day, regardless of BMI level.
There were significant differences (p<0.05) between BMI and ethnic groups for parity, history of diabetes, education, and menopausal status. The average age at diagnosis was 53 years old. The study shows that at the time of the interview obesity was significantly associated with all-cause mortality and non significantly associated with increased risk of breast cancer specific death. However after adjusting for BMI at age 18, duration of estrogen use, total daily energy intake , breast cancer stage and post-breast cancer diagnosis, breast cancer specific was positively associated with obesity among NHW women HR=2.07; 95% CI0.98-4.35,p-trend=0.09; however this association was mainly week in obese Hispanic women HR=1.32;95% CI 0.64-2.74,p-trend=0.50. This difference can not be attributed to loss of statistical power because the number of Hispanic cases was only 7% smaller than the NHW. In some other recent studies, has been hypothesized that the difference between Hispanic and NHW women in the association of obesity with risk and prognosis may be due to different breast cancer phenotypes. Also, another interesting explanation could be ethnic differences in diet, Hispanic diet including items such as soup, sauces, and vegetables was inversely associated with risk of risk of breast cancer. On the other hand the Western diet, mainly consisting in higher intakes of fats and processed foods, was positively associated with breast cancer risk.

Other risk factors
Studies suggest that elevated body mass index BMI may be associated with breast cancer treatment related lymphedema. This study shows that breast cancer survivors whose BMI is ≥30 at the time of breast cancer treatment have a large possibility to develop lymphedema than breast cancer survivors whose BMI is <30 at the time of treatment, also breast cancer survivors who experience an increase in BMI during their first 30 months after they had survive are more likely to develop lymphedema than breast cancer survivors who do not experience at all an increase in BMI.

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