Breast cancer: Types, causes, symptoms and diagnosis

Cancer refers to a condition in which malignant (cancerous) cells grow within the body. With breast cancer, malignant cells develop in the breast. Because male breast cancer is rare, we'll focus on female breast cancer.


Anatomy
The breasts are composed of lobules, ducts and stroma.
Lobules are the glands that produce milk.
Ducts are tubes that connect the lobules to the nipple.
Stroma is the fatty tissue and support structure that surrounds the lobules and ducts.
Blood and lymphatic vessels are also found in the breasts. The lymphatic vessels carry lymph, a clear fluid that helps fight infection and removes tissue waste products. These lymphatic vessels connect to the lymph nodes under the arms, called axillary nodes. A few connect to lymph nodes in the chest and around the collarbone. These lymph nodes help fight infection.


Types of breast cancer
Breast cancer starts most often in the breast ducts and lobules. If it invades nearby breast tissue and lymph vessels, it can then spread via lymph fluid to lymph nodes and other parts of the body. It can also enter blood vessels and spread through the bloodstream to distant organs.
If breast cancer is confined within the lining on which the cells grow (called the basement membrane), it's called noninvasive or in situ. The most common form of noninvasive breast cancer, ductal carcinoma in situ (DCIS), begins in the ducts.

Breast cancer that spreads beyond the lining on which the cells grow is called invasive or infiltrating. The two most common types are infiltrating ductal carcinoma (IDC) and infiltrating lobular carcinoma (ILC).

Inflammatory breast cancer is a rare type of invasive cancer that blocks the lymph nodes and causes the breast to become swollen, warm and red. This is often confused with a breast infection.

Breast cancer that spreads to lymph nodes or to other body organs is called metastatic.


Causes/associated factors
In the United States, breast cancer is second only to skin cancer as the most common form of cancer for women. An estimated 12 percent of all American women will eventually develop breast cancer. Sadly, breast cancer is second only to lung cancer as the leading cause of cancer-related deaths in women.
Although the cause of breast cancer is unknown, certain risk factors have been identified. For example:

Age: The risk of developing breast cancer increases with age. Nearly 80 percent of all breast cancer cases occur after age 50.

Personal history: If you've had cancer in one breast, you have a greater risk of eventually developing cancer in the other breast. A personal history of gynecologic cancer, especially uterine cancer, also increases the risk of developing breast cancer.

Family history: If you have a first-degree relative (a sister, mother or daughter) who's had breast cancer, you're two to three times more likely to develop breast cancer than a woman in the general population, especially if the cancer developed before menopause. The risk increases for every first-degree relative who's had breast cancer. If you have two or more other close relatives, such as cousins or even a male relative who's had breast cancer, you're also at an increased risk. However, it's important to remember that 90 percent of all women who develop breast cancer have no family history of the condition.

Genetics: About 10 percent of breast cancer cases are hereditary. Most of these cases are caused by changes involving the BRCA1 or BRCA2 genes. These genetic changes also put you at a greater risk of developing ovarian or uterine cancer. Changes in the p53 tumor suppressor gene, the ATM gene and the CHEK-2 gene can also increase the risk of developing breast cancer. It's possible to find out if you have any of these genetic defects. If you're considering genetic testing, be sure to thoroughly discuss the pros and cons with your doctor or a genetic counselor.

Race: Statistically, Caucasian women are slightly more likely to develop breast cancer than African-American women. However, African-American women are more likely to be diagnosed at a later stage and, therefore, are less likely to have a successful recovery.

Reproductive factors: The hormone estrogen, which plays a significant role in the menstrual cycle, affects breast tissue. The longer you're exposed to estrogen, the higher the risk of developing breast cancer. If you begin menstruating early (before age 12) or reach menopause late (after age 55), the prolonged exposure to estrogen increases the risk of breast cancer. Likewise, late menstruation, early menopause or premature loss of ovarian function decreases the risk of breast cancer.
Estrogen is suppressed when you're pregnant or breastfeeding. Without pregnancy, your body doesn't experience this lapse in estrogen exposure. Because estrogen levels are highest in your teens and 20s, being pregnant after age 30 doesn't reduce estrogen exposure significantly enough to decrease the risk of breast cancer. However, early or more numerous pregnancies may decrease the risk. Breastfeeding may also slightly decrease the risk.

Some estrogen medications increase the risk of breast cancer. For example, women who took the synthetic estrogen diethylstilbestrol (DES) during pregnancy and women who take combination hormone replacement therapy (estrogen and progesterone) have an increased risk of developing breast cancer. Taking estrogen alone doesn't appear to increase the risk of developing breast cancer. Low-dose birth control pills containing estrogen also don't appear to increase breast cancer risk, but research is continuing. The high-dose pills used in the past may be associated with an increased risk, especially in women who have a family history of breast cancer.


Certain breast conditions: Certain cellular changes in the breast -- especially atypical hyperplasia (the excessive proliferation of cells) -- can increase the risk of developing breast cancer. A breast biopsy (taking a tissue sample for further examination) can detect these cellular changes. Lobular carcinoma in situ (LCIS) is the term used to describe certain abnormal cells in the breast lobules, which are not actually cancer and usually don't become cancerous. It's also called lobular neoplasia. LCIS increases the risk of developing breast cancer, however.
Extremely dense breast tissue, which contains a high proportion of lobular and ductal tissue rather than fatty tissue, places women at a higher risk, especially after the age of 45. Dense tissue may contribute to tumor development since breast cancer often starts in the ducts or lobules. It can also mask tumors on mammograms, making them harder to identify and treat in a timely manner.


Radiation exposure: If you received radiation to your breasts before age 30, particularly if you were treated for Hodgkin's disease, you have an increased risk of developing breast cancer. The younger you were when you received the radiation, the higher the risk.

Obesity: Studies have linked obesity, especially after menopause, to an increased risk of breast cancer. A small amount of estrogen is produced by fat cells. It's thought that having more fat tissue may be at least partially responsible for this increased risk.

Alcohol: Research suggests that the more alcohol you drink, the greater the risk of breast cancer.
It's important to note that the presence of one or more risk factors doesn't mean you're sure to develop cancer. In fact, other than age, most women who have breast cancer have no identifiable risk factors.

Other factors
Researchers are studying other factors to determine how much they affect the risk of developing breast cancer, including:

Abortion: Some studies have indicated a greater risk of developing breast cancer after an abortion, while others have not. Currently, there isn't thought to be an association between abortion and breast cancer.

High-fat diet: The types of fat you consume may play a role in breast cancer development, but research hasn't been conclusive. Further study is needed to better understand the impact of fat intake on the risk of developing breast cancer.
There have been claims that antiperspirants and underwire bras contribute to the development of breast cancer by hindering the flow of lymph from the breast area. There is no scientific data to support these claims.


Signs/symptoms
At first, breast cancer is often painless and without symptoms. In the early stages, symptoms may include:
a lump in the breast, armpit or upper chest
a newly inverted nipple (when the nipple turns in)
nipple discharge, which is often bloody and from only one breast
thickened or dimpled breast skin
nipple itching
change in the size or shape of one breast
any other unusual breast or nipple changes
In the later stages, when the cancer may have spread to other parts of the body, symptoms may include:

breast pain
skin irritation, redness, swelling, or thickening on your breast or nipple
bone pain
abdominal pain
jaundice (yellowing of the skin and whites of the eyes)

Diagnosis
Mammogram
Regular clinical breast exams and screening mammograms (specialized, low-dose X-rays of the inner structures of the breast) are the best ways to detect breast cancer early and improve the odds of successful treatment. Mammograms can often detect breast cancer before any lumps can be felt. Also, mammograms can detect small deposits of calcium in the breast. Although most of these deposits are benign (noncancerous), a cluster of tiny specks of calcium (called microcalcifications) may be an early sign of cancer.

The debate on the timing of mammography continues. Some health care professionals recommend regular mammograms every one to two years beginning at age 40 and annually beginning at age 50. The U.S. Preventive Services Task Force recommends mammograms every one to two years, with or without clinical breast examination, for women age 40 and older. If you have certain risk factors for breast cancer, your doctor may recommend earlier or more frequent screenings. Monthly breast self-exams are recommended by some authorities.

You'll need additional tests if a suspicious area in your breast is detected through a mammogram. For example:

Ultrasound
An ultrasound (using sound waves to create images of internal body parts) can help the doctor distinguish a solid lump that may be cancerous from a benign, fluid-filled cyst. It also helps the doctor see tumors that are difficult to see with a mammogram.

Biopsy
A biopsy must be done to determine if a lump is cancerous. It can be done with a needle or with a surgical procedure. The kind of lump, it's location and your health are all factors that help the doctor decide which type of biopsy is best for you. A local anesthetic to numb the area is usually used. For surgical biopsies, a medication that causes drowsiness is sometimes given prior to the procedure or, occasionally, a light general anesthetic may be used. Mammography or ultrasound may be used to help locate the suspicious area, particularly if it's not easily felt.

Breast biopsy procedures include:

Fine needle aspiration (FNA): This type of biopsy is used more often when a cyst is suspected. The doctor uses a very thin needle with a syringe to remove fluid from the lump. If the lump is solid, however, tissue can be removed and sent to the lab for further examination. This technique isn't always effective in locating cancer cells. To help ensure accuracy, FNA should be done by a doctor who's skilled in the technique. If the lump is still considered suspicious after the aspiration, the doctor may recommend another type of biopsy.

Core needle biopsy: With this type of biopsy, the doctor uses a local anesthetic to numb the area. A slightly larger needle is then inserted through the skin. Several small cores of the lump are removed and sent to the lab for examination. This type of needle biopsy is used more often than FNA.

Stereotactic breast biopsy: With stereotactic breast biopsy, the doctor uses a three-dimensional X-ray or mammogram to direct the way to the suspicious area. Then, with a computer-guided small needle, the doctor takes tissue samples for evaluation. More study is needed, but it appears that this less invasive biopsy may be as accurate as a surgical biopsy.

Excisional biopsy: With an excisional biopsy, the surgeon makes an incision in the contour of the breast and removes the entire lump and some of the normal tissue around it. The tissue is then sent to the lab for examination. This type of biopsy is usually done for lumps that are less than an inch in diameter. The procedure takes about an hour, and you'll usually go home within an hour or two.

Incisional biopsy: The procedure for an incisional biopsy is similar to that of an excisional biopsy, but only a portion of the lump is removed. It's usually used for larger lumps.

Localization biopsy: Before a biopsy procedure, the suspicious lump is located on a mammogram or with ultrasound. A needle is inserted into the breast until it reaches the lump, and its position is then verified with mammogram or ultrasound. For a needle biopsy, tissue samples are then taken. For a surgical biopsy, a wire is inserted through the needle to the lump, the needle is removed, and the wire is left in place. It's then taped to the skin and the surgical biopsy is done.
Diagnostic research
New diagnostic tests, such as ductal lavage, are under investigation. With this test, a needle inserted in the nipple is used to remove breast cells from the milk ducts. Local anesthetic is used to prevent discomfort. Currently, this technique is being investigated as a procedure for early detection with women who are at high risk for breast cancer, but have no symptoms. It's too early to say if this will be a useful diagnostic tool.

Staging
If cancer cells are found during your biopsy, the doctor will use a process called staging to determine how far the cancer has spread. Staging also allows the doctor to determine the most appropriate treatment plan, as well as the prognosis.

Breast cancer staging is most often based on the TNM staging system: tumor, node and metastasis. This system provides detailed information about tumor size and whether it has spread to nearby tissues (T), lymph nodes (N) or other areas of the body (M). The TNM information is combined to describe the overall stage of the cancer, expressed as stages 0 through IV.

Stage 0: This is cancer in situ, or noninvasive cancer, that hasn't spread within the breast or elsewhere.

Stages I and II: These are the early stages of breast cancer. The tumor has become invasive and spread to nearby tissue, but it's only in the breast or some of the axillary lymph nodes.

Stage III: This is locally advanced breast cancer. The tumor has spread to the skin or the wall of the chest, or it has more extensively invaded the lymph nodes and is now found in nodes near the breast bone or is causing axillary nodes to mat together.

Stage IV: This is metastatic or advanced breast cancer, which has spread to other parts of the body, such as the bones, liver or lungs.

Staging may require further testing such as blood tests, more biopsies, a chest X-ray, mammograms of both breasts, a bone scan and computed tomography (CT scan, a computer-generated, cross-sectional picture of internal body parts) or magnetic resonance imaging (MRI, an imaging technique based on computer analysis of the body's response to a magnetic field).

In some cases, additional tests may be done on the tissue removed from the breast, giving the doctor more information to help determine the most effective treatment for your type of cancer. For example, hormone receptor testing can determine whether your hormones (estrogen or progesterone) stimulate the cancer cells grow. If they do, then the cancer is likely to respond to hormone therapy, which blocks the action of the hormones. HER-2/nue (human epidermal growth factor receptor-2) testing can detect breast cancers that have too much of the HER-2/neu protein, which may cause the tumor to grow rapidly.

Except for carcinoma in situ (stage 0), staging also requires examination of the axillary lymph nodes for cancer cells. This can be done before treatment or as part of breast cancer surgery. Axillary lymph node dissection (lymphadenectomy) is the complete or partial removal of the axillary nodes. It's effective in finding cancer cells, but can sometimes lead to complications in the arm, such as swelling, numbness or infection.

Recent research has indicated that a newer procedure, sentinel node biopsy, may be as effective as lymph node dissection. A dye or radioactive solution is injected near the tumor and traced as it enters lymph vessels and travels to the lymph nodes. The first node that it reaches, the sentinel node, is removed and examined for cancer cells. If there are none, then no other nodes are removed. If cancer cells are found, other nodes must be removed to stage the cancer.


Recurrence
Recurrent cancer is described as cancer that returns either in the breast or somewhere else in the body after treatment. Treatment for recurrent breast cancer depends on the initial treatment, but usually involves hormone therapy, radiation, chemotherapy or surgery.
A recent study found that letrozole (Femara, for example) may reduce the recurrence of breast cancer by 43 percent in postmenopausal women who've completed five years of tamoxifen therapy. The study was stopped early so women could begin to receive this treatment. Letrozole works by suppressing the production of estrogen. Side effects of letrozole may include low-grade hot flashes, joint and muscle pain, and arthritis. There was also a slightly higher rate of osteoporosis in women who took letrozole compared to those in the study who took a placebo. Further research is needed to determine the long-term benefits and risks of letrozole.

Anastrozole (Arimidex) is an aromatase inhibitor that suppresses the production of estrogen. It's been shown to be as effective as Tamoxifen.


Complications
Complications of breast cancer are often related to treatment.
Complications from surgery may include infection, fluid accumulation in the wound or arm, numbness and limited arm motion.

Chemotherapy can have severe side effects, including nausea, vomiting, impaired immune function and hair loss.

Radiation may cause burns to your skin, fatigue and heart damage.

Hormone therapy can cause weight gain and blood clots. Depending on your personal history, it may even increase the risk of other types of cancer.

Pregnancy-specific information
Since the breasts are normally tender and swollen during pregnancy, small lumps are hard to detect and diagnosis at an early stage. Breast cancer can occur during pregnancy, however. If you notice a suspicious lump or any other symptoms, consult your doctor.
The increased density of the breasts during pregnancy gives mammography limited value during this time. Biopsies are often recommended, using a local anesthesia that's safe for you and the baby.

Treatment may include surgery or chemotherapy. Of course, treatment options are different during pregnancy due to potential risk of harm to the baby. Discuss any concerns with your doctor.


Senior-specific information
Nearly 80 percent of all breast cancer cases occur after age 50. Regular clinical breast exams and screening mammograms are the best way to detect breast cancer early and improve the odds of treatment success. Some health care professionals recommend yearly mammograms for women age 50 and older. Consult your doctor to determine the best screening schedule for you.

Prevention
Here are some steps to help prevent breast cancer or detect it at an early stage.
Limit alcohol intake.

Exercise regularly and maintain a healthy body weight.

Limit your intake of fats derived from animal products.

Carefully consider genetic testing if you have a strong family history of breast cancer. Be sure to thoroughly discuss the pros and cons with your doctor or a genetic counselor.

If you have a high risk of developing breast cancer, ask your doctor about tamoxifen therapy. According to a recent study, tamoxifen can significantly reduce the risk of developing breast cancer for certain at-risk women. A preventive mastectomy may also be possible.
Breast self-exams
Although many medical organizations still endorse monthly self-breast exams, its usefulness is in question. Recent studies have shown that monthly breast self-exams don't appear to decrease the number of deaths due to breast cancer. The U.S. Preventive Services Task Force recently cited an association between breast self-exams and an increase in benign breast lump biopsies. They state that no evidence exists to recommend either for or against regular breast self-exams, but they can't rule out that other potential benefits may exist.

Clinical breast exams
It's important to see your doctor for clinical breast exams. Some health professionals recommend clinical breast exams every two to three years between ages 20 and 39 and every year beginning at age 40. The U.S. Preventive Services Task Force concluded that there's insufficient evidence to recommend for or against routine clinical breast exams alone to screen for breast cancer.

Mammograms
The debate on the timing of mammography continues. Some health care professionals recommend regular mammograms every one to two years beginning at age 40 and annually beginning at age 50. The U.S. Preventive Services Task Force recommends mammograms every one to two years, with or without clinical breast exams, for women ages 40 and older.

Based on your age and other risk factors, decide with your doctor how often to do breast self-exams and have clinical breast exams and mammograms.