Breasts and their function

A sign of fertility, the mark of life-giving milk. These are quotes used in earlier times to describe a woman's breasts. Ancient paintings and representations of woman goddesses often emphasized the breasts as the sign of motherhood and child-bearing. Today, the way one views a woman certainly has changed to a more independent and liberal outlook but the function of the breasts in procreation still remains the same - they are vital to the nourishment and immunity of a newborn child. Through the lactation of breast milk infants are provided with a mixture of lactose, fats, ions, vitamins, immunoglobulin A and casein which binds calcium. [1]

Basic Anatomy of the Breast

The basic layout of the breast is shown in this simplified diagram depicting the nipple, which is raised, and the areola which is the darker circle. The nipple usually extends a few millimeters from the breast and is surrounded by the areola. Areola, like the nipple, varies in diameter but is usually between 1.5-2.5mm. The dotted like structures on the areola are modified apocrine glands, sweat glands and sebaceous glands [2]. The dark pigmentation seen in the areola is due to the network of capillaries that carry blood very close to the surface. This dark colour first appears more apparent at puberty and also darkens again during pregnancy[2].

Stages of Breast Development

How it all begins

Believe it or not, breast development begins within the wound as early as the 4th week of life as a fetus. Breasts are ectodermally derived and first begin as thickenings of the epidermis that extend from the armpit to the groin forming the 'mammary lines' or 'milk lines' [2]. By the 9th week, the milk lines are reduced to the chest area leaving only 2 bud like structures. Primitive vessels develop and near the 13th week the nipple as well as areola appear[3].

Birth

The mammary gland is present as a disk of about 1 cm in thickness. From here on in the breasts remain dormant while the mammary glands change with lobes and galactophores (ducts in the breast) beginning to form [3].

Puberty

The stages just before development and during are summed up into 5 stages as originally proposed by Tanner [4]:
Stage 1: Preadolescent: Tip of the nipple is raised
Stage 2: Buds appear, now the breast is raised as well. The areola enlarges
Stage 3: Breasts are a little larger and some glandular tissue is present
Stage 4: Areola and nipple are now raised which form a mound
Stage 5: Mature Adult: Breast round and only the nipple is raised

A more indepth view of the breast

Breasts are composed of two major tissue types:
1) glandular tissue - responsible for the mammary glands which produces milk
2) adipose tissue - fatty tissue

The adipose tissue is considered subcutaneous and lie under the skin of the breast. Glandular tissue is located in front of the pectoral muscle[5].The mammary glands are from cutaneous origin. They consist of a network of tubules called lactiferous ducts which are supported by loose connective tissue followed by dense connective tissue and adipose tissue. The dense tissue divides into septa between the ducts divide the mammary gland into lobes [2]. These lobes are made up of lobules which contain alveoli. These alveoli also are composed of lactocytes which are secretory epithelial cells responsible for the secretion of breast milk [5]. Structurally the alveoli are connected to the smaller ducts which join together to form larger ducts draining the lobules. The larger ducts also join into one milk duct for each lobe that eventually ends in the lactiferous sinus which is the opening of the nipple [5]. The ducts themselves consist of stratified cuboidal epithelium which is made up of inner secretory cells and outer myoepithelial cells [1] while the inner sinus in the nipple is lined with a double layer of stratified cuboidal epithelium. As the outside of the nipple is reached the tissue gradually gives rise to keratinized stratified squamous epithelium [2].

Figure 2: Nonlactating breast showing lactiferous ducts, loose connective tissue, dense connective tissue and adipose tissue [1]
Figure 3: A closer look at a lactiferous duct [2]


The areola is covered with a thin layer of stratified squamous epithelium. This layer contains keratin and is continous over the entire breast, including the exterior of the nipple. The dermis, comprised of elastic connective tissue, extends deep into the skin and forms irregular dermal papillae [2].

Figure 4: A closer look at the nipple [2]

FACT OF THE DAY!!

Mammary glands resemble sweat glands and are actually derivatives of eccrine sweat glands[1]

The transformation of breasts during pregnancy

During pregnancy

If you have ever been pregnant or know someone who has been, one of the obvious transformations during pregnancy (besides the belly of course!) is the breasts. During pregnancy the body produces hormones such as estrogen, progesterone, prolactin, human chorionic somatomammotrophin, thyroid hormone and corticosteroids. The secretion of these hormones by the placental and corpus luteum causes the terminal duct epithelium in the breasts to grow and more secretory acini to be developed [6]. Inner secretory cells in the breast tissue also become bigger and the alveoli eventually contain breast milk [1].

Figure 5: a) The lobules (Lo) have enlarged while the septa (S) remain the same size while dividing the breast into lobes. b) acini (A) are dilated and the epithelial cells (E) show cuboidal structure as well as low columnar. The dilation of the acini and the ducts is due to the accumulation of colostrum [6].Colostrum is the first secretion of the breasts after pregnancy. It consists of a laxative and maternal antibodies.

When a women begins lactating the breast again changes.
Figure 6: The lactating breast. The important feature to take from this is the myoepithelial cells (M) which are the secretory cells that contract to actually expel the milk. The lipid droplets (L) also seem to take up a large amount of space and are discharged in apocrine secretion [6], which could account for why breast milk is so high in fatty content. IgA, produced by plasma cells in the connective tissue surrounding alveoli [1], is also released into the milk via transcytosis by the small vesicles (V). Protein is developed by the rough endoplasmic recticulum (rER) and small protein granules can be seen by the black dots in the micrograph [6].

Suckling

Once the baby is born and begins suckling the breast, two neurohormonal reflexes occur:
1) prolactin is released by the anterior pituitary which stimulates milk production [6]
2) oxytocin is released by the posterior pituitary which causes myoepithelial cells to contract. These cells are located around the secretory acini and ducts, so it causes milk to be pushed down the ducts and eventually out the nipple [6]

If suckling stops then these hormones are not released and the lactating breast regresses [6].

DID YOU KNOW??

For effective output of the milk, it is suggested that the baby should have a large portion of the areola in the mouth [5].

A Breast's Worst Enemy

Cancer is when our cells proliferate out of control forming large masses or lumps called tumors. If cancerous cells reach the blood stream or lymphatic tissue they can migrate to other parts of the body [7]. Tumors can be either benign, where they remain in one place and do not threaten the person's health, or malignant where they move to other places in the body and invade surrounding cells [7].
In women, cancer of the breast is the most common malignancy [8]. Statistically approximately 1 in 10 women will develop a form of breast cancer [1], which can be a scary thought when sitting in a class surrounded by 20 or more women. Alot of breast tumors arise from the epithelium of lactiferous ducts ( Ductal Carcinoma) and are treated by surgical procedures that cut out that portion of the breast to stop the cancerous cells from spreading into circulation [1]. Other types of cancer are caused by mutations in various proteins. One particular protein that suppresses the formation of tumors is BRCA1/BRCA2. When mutations occur in these proteins the chance of developing cancer is heightened. About 5-10% of all types of breast cancer originate from mutations in these important proteins [1].
HER2 is another important protein that regulations cell proliferation. Mutation in this protein also increases the risk of cells dividing out of control. 30% of cancers are associated with mutation in this protein [1].

Factors increasing likelihood of breast cancer [7]

• If you have a family history of breast or ovarian cancer or if you have had cancer before.
• If you have never had children or gave birth for the first time after 30
• Began menstruation early or reached menopause late
• If you had hormone replacement therapy (exposure to increased amounts of estrogen)
  
• If you have denser breast tissue
• If you are obese, drink alcohol, or are on the 'pill'

What are the signs of breast cancer? [7]

• lump in the armpit
• changes in your breasts including shape and size
• swelling, redness and a warm feeling in your breast(s)
• puckering of the skin, inverted nipple (This is only dangerous if it is a new condition [3])
• scaling on the nipple

Diagnosis of breast cancer [8]
Keep in mind that if you have symptoms you may not have breast cancer, these symptoms are not uncommon in a normal woman. Usually further analysis is needed for a certain diagnosis. One method used is a 'triple assessment'. This includes three main assessments before reaching a decision: a clinical assessment, imaging (ie. a mammogram, ultrasound) and closer look at the cytology of the cells through a fine needle aspiration, a needle core biopsy or a breast core biopsy. However, methods are not always 100% certain. Tests may need to be completed more than once so your doctor can be sure of the condition of your breasts.
Treatment of breast cancer

Once diagnosed treatment generally follows similar trend to treatment of other cancers and can include [7]:

• surgery
• chemotherapy
• hormone therapy
• biological therapy
• radiation therapy

Some other notable treatments have been developed. One is the use of an antiestrogen compound called "tamoxifen". This acts by binding to estrogen receptors and changing its shape so certain steroid co-activator proteins cannot bind, and DNA transcription cannot occur. Hence cells cannot proliferate [1]. Antibodies to the HER2 protein mentioned above have been developed and found successful in preventing mutations in this protein.

So how can you protect yourself?
Follow the seven steps to Health, outlined by the Cancer Society [7]:

1) Don't smoke and avoid second hand smoke

2) Eat right

3) Get active!

4) Protect yourself from the sun

5) Follow cancer screening guidelines

6) Visit your doctor regularly

7) Follow hazardous and safety instructions

Breast Self-Examination

Following these simple steps can keep you up to date on your health. If done on a regular basis you can easily recognize any changes in the shape or size of your breast. More information can be found at the Forrest General Hospital Cancer Services

7 P's of a Good BSE
1. Positions
Standing:

* First, stand in front of a mirror with your arms relaxed at your side.
* Then place your hands on your hips.
* Raise arms above your head.
* Bend slightly forward, allowing your arms to hang freely toward the floor.

In each position, look for changes in contour and shape of the breast, color and texture of the skin and nipple, and evidence of discharge from the nipples.
Palpation: Side-lying and flat:

* Use your left hand to palpate the right breast, while holding your right arm at a right angle to the rib cage, with the elbow bent.
* Repeat the procedure on the other side.
* The side-lying position allows a woman, especially one with large breasts, to most effectively examine the outer half of the breast. Do this by lying on the opposite side of the breast to be examined. Rotate the shoulder (on the same side as the breast to be examined) back to the flat surface.
* A woman with small breasts may only need the flat position. Lie flat on your back with a pillow or folded towel under the shoulder of the breast to be examined.

2. Perimeter

Visualize the perimeter of the breast as an imaginary line which extends down from the middle of the armpit to just beneath the breast. The imaginary line continues across along the underside of the breast to the middle of the breast bone, then moves up to and along the collar bone and back to the middle of the armpit. Most breast cancers occur in the upper outer section of this area (towards the shoulder and armpit).
3. Palpation

With Pads of the Fingers: Use the pads of three or four fingers to examine every inch of your breast tissue. Move your fingers in circles about the size of a dime. Do not lift your fingers from your breast between palpations. You can use powder or lotion to help your fingers glide from one spot to the next.
4. Pressure

Use varying levels of pressure for each palpation, from light to deep, to examine the full thickness of your breast tissue. Using pressure will not injure the breast.
5. Pattern of Search

Use one of the following search patterns to examine all of your breast tissue. Palpate carefully beneath the nipple. Any incision should also be carefully examined from end to end. Women who have had any breast surgery should still examine the entire area of the incision:

* Vertical Strip: Start in the armpit, proceed downward to the lower boundary. Move a finger's width toward the middle and continue palpating upward until you reach the collarbone. Repeat this until you have covered all breast tissue. Make at least six strips (passes with your fingers) before the nipple and four strips after the nipple. You may need between 10 and 16 strips.
* Wedge: Imagine your breast divided like the spokes of a wheel. Examine each separate segment, moving from the outside boundary toward the nipple. Slide fingers back to the boundary, move over a finger's width and repeat this procedure until you have covered all breast tissue. You may need between 10 and 16 segments.
* Circle: Imagine your breast as the face of a clock. Start at 12 o'clock and palpate along the boundary of each circle until you return to your starting point. Then move down a finger's width and continue palpating in ever smaller circles until you reach the nipple. Depending on the size of your breast, you may need eight to 10 circles.

6. Practice With Feedback

It is important that you perform a BSE while your instructor watches to be sure you are doing it correctly. Practice your skills under supervision until you feel comfortable and confident.
7. Plan of Action

Every woman should have a personal breast health plan of action:

* Discuss the American Cancer Society breast cancer detection guidelines with your health care professional.
* Schedule your clinical breast examination and mammogram as appropriate.
* Perform a BSE monthly. Ask your health professional for feedback on your BSE skills.
* Report any changes in your breast to your health care professional.

Myths of Breast Cancer

It seems like every year we find more and more factors contributing to cancer. However, among all this information are some beliefs concerning breast cancer that are actually MYTHS [10]

1) Men can't get breast cancer
2) Underwire bras cause breast cancer
3) Women under 40 don't get breast cancer
4) Deoderants cause breast cancer
5) Birth Control Pills cause cancer (although there has been studies showing slight association [7] there is no direct link)
6) Mammograms spread breast cancer
7) A lump in the breast is always breast cancer
8) Breast cancer can only develop in one breast, not both
9) A mastetomy is the only treatment
10) The smaller the your breasts the smaller the chance of developing breast cancer

Associated links to breast cancer, definitely worth a look:

Canadian Cancer Society
All About Breast Cancer
Health Canada
Breast Cancer Society of Cancer
The Weekend to End Breast Cancer


At our own university there is a comprehensive Masters in Science program in Medicine that specializes in cancer research. Some of the supervisors specialize in breast cancer research and are strong supporters of breast cancer research. Dr. Jon Church in particular has made tremendous efforts to help those with breast cancer. He owns and administrates an internet discussion listserv called "BREAST-CANCER" where over 600 people from 30 countries can discuss topics on breast cancer. He also uses an audio teleconference twice a month as a means of support for woman suffering from breast cancer and coordinates a world wide web page that was recognized in 1997 by Snap! Online and HealthyWay as " Best of the Web".
Dr. Gary Paterno is another researcher at Memorial that completes work directed towards breast cancer. He currently is studying the regulation of estrogen receptor activity and it's role in breast cancer.

Final word...

I advise you to skim through the various websites, they are a great resource and have many different events involving breast cancer awareness that would be great to get involved in. Expand your knowledge on such an important issue and spread the word about the different risk factors of breast cancer.
Lastly, I urge women of all ages to follow the guidelines outlined throughout this blog. See your doctor, have regular breast examination, TAKE CARE OF YOURSELF! There's only one you, so do what you can to keep healthy and avoid risks associated with breast cancer.

References

[1] Netter's Essential Histology
By William K. Ovalle, PhD, University of British Columbia, Department of Cellular and
Physiological Sciences, Vancouver, BC, Canada; and Patrick C. Nahirney, PhD, Bethesda, MD
ISBN 1929007868 · Paperback · 512 Pages · 1200 Illustrations
Saunders · Published September 2007

[2] Wheater's Functional Histology, 5th edition
A Text and Colour Atlas
By Barbara Young, BSc, Med Sci (Hons), PhD, MB, BChir, MRCP, FRCPA, Consultant
Pathologist, North Glasgow University Hospitals NHS Trust, Western Infirmary, Glasgow, UK; James S. Lowe, BMedSci, BMBS, DM, FRCPath, Professor of Neuropathology,
University of Nottingham Medical School, Honorary Consultant Pathologist, Queen's
Medical Centre, University Hospital NHS Trust, Nottingham, UK; Alan Stevens, MBBS,
FRCPath, Senior Lecturer in Pathology, University of Nottingham Medical School and
Honorary Consultant Pathologist, Queen's Medical Centre, University Hospital NHS Trust, Nottingham, UK; and John W. Heath, BSc, Hons(Melbourne), PhD, (Melbourne), Associate
Professor in Anatomy, The University of Newcastle, New South Wales, Australia
ISBN 044306850X · Paperback · 448 Pages · 849 Illustrations
Churchill Livingstone · Published March 2006

[3] Stines, J., Tristant, H. (2005). The normal breast and its variations in mammography.
European Journal of Radiology. 54: 26-36

[4] Tanner, JM (1969). Growth of adolescence. Oxford: Blackwell Publishing.

[5] Ramsay, DT., Kent, JC., Hartmann, RA., Hartmann, PE. (2005). Anatomy of the lactating human breast redefined with ultrasound imaging. Journal of Anatomy. 206: 525-534

[6] Elsevier's Integrated Histology
By Alvin G. Telser, PhD, Department of Cell and Molecular Biology, Northwestern
University, Feinberg School of Medicine, Chicago, IL; John K. Young, PhD; and Kate M.
Baldwin, PhD
ISBN 0323033881 · Paperback · 464 Pages · 455 Illustrations
Mosby · Published June 2007

[7] Canadian Cancer Society Website

[8] Bateman, AC. (2007). Breast pathology. Basic Science. Elseiver Ltd.

[9] Forrest General Hospital Website

[10] About.com :Breast Cancer Myths