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5Wschodnioeuropejskie Czasopismo Naukowe (East European Scientific Journal) #11, 2016 IIIB§9JMj
NAUKI MEDYCZNE I NAUKI O ZDROWIU / MEAMUMHCKME HAYKM
BONE MASS AND THE RISK OF BREAST CANCER
Dimitar Minkov Minkov
MD, PhD Orthopaedic and Traumatology Specialist Avis Medica Hospital, Pleven, Bulgaria
Bone mass density has been allied to reduced jeopardy of breast cancer, in particular to the aged female. Traditionally, breast cancer was linked to factors such as the history of the disease in first-degree relatives, late menopause, early menarche, obesity, and late age at full-time pregnancy and nulliparity. However, studies have associated the bone mass density to breast cancer with the primary link being estrogen. This hormone has an essential task in the regulation and development of the female reproductive system as well as the secondary characteristics. In addition, estrogen has a crucial function in the regulation of the bone mass through controlling bone formation activity through the osteoblasts and bone re-absorption by the osteoclast. The breast cancer cells have receptors on which other proteins can attach to, thus, end up simulating the growth of cancerous cells. Breast cancers that have the presence of the estrogen hormone are known as estrogen-receptor positive cancer.
Keywords: breast cancer, estrogen, bone mass, calcium, vitamin D
Introduction
Breast cancer is believed to originate in the lobules, which supply the milk ducts. The kind of the condition originating from the lobules is referred to as Lobular carcinoma while that originates from the duct is referred to as Duct carcinoma. Numerous breast cancers cases occur in the female. The condition has become one of the most common invasive cancers among women globally. In all female cancers, it accounts for about 16% and 22.9% of all invasive cancers. Globally, there are about 1,150,000 new cases of breast cancer development with about 410,000 deaths [1]. There are 215,000 new breast cancer cases each year and 410,000 deaths in the United States. Traditionally, breast cancer was linked to factors such as age, genetics, family history about the condition, development of benign breast lumps, dense breast tissues, exposure to estrogen, uncontrolled drinking of alcohol, obesity exposure to radiation, and hormonal replacement therapy. However, new studies have found the existence of an association between the bone mass density and the development of breast cancer. This paper entails the risk of developing breast cancers in the female who are subjected to high bone density as compared to their counterparts with reduced bone density.
Bone Mass
Bones are the body's framework made up of living tissues that constantly change. The bones grow at a high rate during the adolescent stage. Girls are believed to have attained about 90% of the required bone mass at 18 years. Bone mass is the amount of body tissue found in the skeleton. Research have found that there is minimal change to the bone mass in women who are about to reach menopause [2]. However, women tend to experience increased rates of bone mass loss in their early days of menopause, which develops progressively until post-menopause. Many factors are contributing to the decrease in bone mass, which include low Calcium and vitamin D diets, poor physical activity, tobacco and alcohol use, gender differences, body sizes, age, family history, hormonal levels, and certain medications such as a corticosteroid. Vitamin D deficiency and low Calcium content have been indicated as the major causes of the reduced bone mass.
Calcium
It is the most crucial mineral in the body. It is believed that an adult individual has about 1000g of Calcium. The element is of the essence in the formation of minerals within the skeleton. This element is availed to the human body through dietary intake, whereby the recommended intake is estimated at 1000-1500 mg/d depending on the age of the individual. However, there has been controversy over the amount of Calcium consumed by women. In the United Kingdom, the amount of the element considered for postmenopausal women is 700mg/d while in the United States, is 1500mg/d [3]. About 99% of the Calcium is found in the skeleton in the form of Calcium Phosphates. It has two major functions inside the bones: provision of skeletal strength and acting as a dynamic store for the maintenance of intracellular and extracellular Calcium pools [4]. The non-bone Calcium forms only 1% of the body's Calcium, which has crucial functions in the human body. A bone density test is used to determine the density of the different minerals inside the bones such as Calcium [4]. The information from the test determines the bone mass and their strength. The bones tend to grow thinner conditions osteopenia as an individual becomes old [5]. This is because the rate at which the older bones are broken down is higher than that of formation of new bones. Due to the development of osteopenia, the bones tend to lose a lot of Calcium and other bone minerals, thus, becoming porous and less dense [6]. The bones become weaker and are easily prone to fractures. Continued cases of osteopenia may lead to osteoporosis. This condition is common in women who have attained postmenopausal age. However, they can reduce the bone loss if they take Calcium supplements such as Calcium Carbonate and Calcium citrate [7].
Calcium balance
It is said to be the state of the body where Calcium level is maintained at equilibrium over a given period. The Calcium balance depends on the net effects that occur in the renal, intestinal absorption and glands secretion such as sweat on the bone where Calcium is the main element [8]. Throughout the lifespan of an individual, Calcium-bone balance tends to change based on the rate of the formation of the bone and reabsorption. Young kids are found to have positive Calcium-bone balance that
© Dimitar Minkov Minkov, 2016
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guarantees they attain the required skeletal growth balance [9]. It is of the essence to note that the young healthy individuals have a neutral bone balance since they have attained the required bone mass, whereas the adults have a negative balance that leads to the age-related loss of bones.
Vitamin D
The chief source of the mineral is the human body through the skin. It is produced when the ultraviolet rays are captured by the steroid precursor. Also, it is present in some limited foods such as fish oils, fish, and dairy products that in the case of a decreased sunlight exposure, the dietary sources can be used to supplement Vitamin D to the body [10]. However, it is not a real vitamin for it exists in the form of a pro-steroid hormone, which is inert. This is until the liver into 25-hydroxyvitamin D metabolizes it (25 (OH) D). Its importance in the bone formation process since it is attributed to the promotion of the intestinal absorption of Calcium and mineralization of the bone matrix [11]. This is through the regulation of metabolism and homeostasis of Calcium and the Phosphates. Ascorbic acid conducts a significant task in the apoptosis of the cancerous cells through slowing down their proliferation. Studies have indicated that the skin synthesizes Vitamin D. However, several food products such as fish oils, fish, and dairy products are rich in Vitamin D. Vitamin D helps in the regulation of calcium within the body [12]. Calcium is known to be an essential element in the formation of bones, which is assisted by the presence of Vitamin D. In addition, it extends the lifetime of the osteoblast through the inhibition of the apoptosis [13]. Researches indicate a correlation between the osteoblasts and estrogen. It is evident that Calcium and Vitamin D conducts an essential function in the bone formation within the human body. A deficiency of these two elements would lead to osteoporosis [14]. According to the World Health Organization, osteoporosis is a condition of bone mineral density, which lies below a standard deviation of 2.5 or below an average young health woman's value (a T-score of <-2.5 SD) [15]. This criterion by the World Health Organization was accepted by numerous member states. The most common means by which the bone mineral density is measured is through an X-ray absorptiometry (DXA) or a diagnostic criterion, which is based on the T-score for bone mineral density [16].
Bone Mass and Breast Cancer
It is an indication of a low bone mineral density when a woman is diagnosed with osteoporosis. This means that the woman has a low risk of contracting breast cancer. In all females, the
bone mineral density reflects their endogenous and exogenous exposure to estrogen [17]. Women with long reproductive life because of early menarche and late menopause are known to have high bone densities than their counterparts with early menopause and late menarche [18]. The densities of the bones deteriorate after a woman has attained menopause unless they involve themselves in taking of post-menopausal hormones. The factors that enable females to have a higher bone mineral density are said to as well support the development of breast cancer. This explains why female with high bone mineral densities is at a higher menace of developing the condition unlike those with lower bone densities [19]. Bone mass densities have been linked to the levels of estrogen in the female's body. Menopause is a period in the life of a woman, whereby menstruation has reached final stage due to reduced production of estrogen by the body. With a decrease in estrogen level, osteoporosis may occur. Bone cells have two types of intracellular steroids receptor for estrogen [20]. A combination of estrogen to these receptors activates several genes. Estrogen is mediated by certain growth factors and interleukins, which acts as an active simulator in the bone reabsorption process. The hormone prevents the osteoblasts from synthesizing interleukin 6, whereby it may antagonize the interleukin six receptors; thus, preventing the development of osteoporosis. Estrogen regulates osteoclast apoptosis, whereby its deficiency means the osteoclast will have a longer life span and in the process, they will reabsorb more bones [21]. An increase in bone reabsorption increases the rate of formation of new bone, which leads to the loss of the old bones. In women who have undergone a natural menopause, within five years of its occurrence, they experience a loss of the trabecular architecture. This is clear indication that the estrogen has a function in the continuance of the bone mass. As women reach menopause, they experience a deficiency in estrogen levels leading to low bone mineral density. This translates to them having a low risk of breast cancer development.
Conclusion
Our primary data set was compiled from 20 studies that were published between 1976 and 2015 in different journals such as Journal of National Cancer of Institute, American journal of clinical nutrition, Journal of clinical entomology and metabolism, New England journal of medicine, and Jama among others. There are limitations to the use of these sources for each of them at the time has its comparison between the bone mass density and breast cancers.
Bibliografy
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