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Breast cancer is the second most common cancer in women after skin cancer. While there are some factors that a person cannot change to lower their risk for breast cancer, there are many other factors that can be modified to lower risk for the disease. Some people also carry an inherited or genetic risk for breast cancer.

Most breast cancers are carcinomas, or tumors that begin in the epithelial cells that line organs and tissues throughout the body. About 90% of breast cancers are adenocarcinomas, which arise from glandular tissue.

Ductal carcinoma (DCIS) is the earliest form of breast cancer and develops solely in the milk ducts. According to the National Cancer Institute (NCI), the most common type of breast cancer, invasive ductal carcinoma, develops from DCIS, spreads through the duct walls, and invades the breast tissue.

Cancer that begins in the breast lobes (or lobules) is called lobular (small cell) carcinoma and is more likely to be found in both breasts. Invasive lobular carcinoma originates in the milk glands and accounts for 10-15% of invasive breast cancers. Both ductal and lobular carcinomas can be either in situ (self-contained) or infiltrating (penetrating the wall of the duct or lobe and spreading to adjacent tissue).

Breast cancer screening with mammograms can help detect breast cancer early. People at high risk for breast cancer may need to undergo additional imaging exams, such as breast ultrasound and/or breast MRI. It is important to have a breast cancer risk assessment done to determine if you are at high risk or not.

However, a person may spot a potential health problem on their own through breast self-examination. Regular examination of breast tissue both visually and manually may reveal changes in breast size or shape, swelling or distortion, dimpling, puckering, or bulging.

What are some of the risk factors that you cannot change in terms of breast cancer risk?

• Growing older
• Family history of breast or ovarian cancer
• Personal history of breast cancer or other noncancerous/precancerous breast diseases
• Inherited genetic mutations, especially BRCA1 and BRCA2, which carry a higher risk for breast and ovarian cancers
• Dense breasts, which may make it harder to see tumors on mammograms
• Starting menstruation before age 12 and starting menopause after age 55
• Never having a full-term pregnancy

What can you do to lower breast cancer risk?

• Be physically active
• Maintain a healthy weight, especially after menopause. Overweight or obesity in older women has been tied to a higher breast cancer risk
• Drink alcohol only in moderation
• Avoid or quit smoking tobacco products
• If you have a strong family history of cancer or certain genetic mutations, you may need to undergo additional routine exams, such as a breast MRI. Also, talk to your healthcare provider about others ways to reduce your risk, such as with medicines that block or decrease estrogen in your body, or surgery.

Is all breast cancer the same?

There are many different types of breast cancer. The type is determined by the specific cells in the breast that become cancerous. As noted, breast cancer most often originates in the ducts or lobules of the breast. If the cancer is "in situ," it is a precancer that begins in the milk ducts but has not grown into the rest of the breast tissue. If the cancer is invasive or infiltrating, the cancer has spread from the ducts or lobules into the surrounding breast tissue.

Invasive breast cancers may develop in certain ways that will play a part in treatment and response to treatment.

It is important to determine if the cancer has estrogen receptors (ERs) or progesterone receptors (PRs), as determined by a pathology test on a sample of tumor tissue. The NCI notes that if the cancer has ERs, it is said to be estrogen-receptor positive, and if not, the cancer is said to be estrogen-receptor negative. Similarly with PRs.

Tumors that are ER- or PR-positive depend on the patient's natural hormones to grow. If a tumor is ER positive, anti-estrogen therapy, such as the drug tamoxifen (Nolvadex), will block the receptor and help prevent the cancer from growing.

Another important breast cancer receptor is the human epidermal growth factor receptor 2 (HER2). This receptor controls how breast cells grow and divide. As determined by a pathology test, if the breast tissue has too many HER2 receptors (i.e., overexpression), the breast cells can grow and multiply too quickly, and if uncontrolled, can lead to cancer.

Breast cancer identified as HER2-positive tends to grow faster, spread (metastasize), and come back (recur). While HER2-positive cancer may be aggressive, it also responds better to breast cancer treatment that targets HER2 proteins. There are no unusual symptoms or breast cancer risk factors associated with HER2-positive breast cancer, although some studies suggest that HER2-positive status is more common among younger women.

One type of invasive breast cancer is triple-negative breast cancer, which accounts for about 15% of cases. The term "triple negative" refers to a lack of certain hormones and proteins in the cancer cells.

Another aggressive type of invasive breast cancer is inflammatory breast cancer, which accounts for up to 5% of cases. Here, the breast can appear "inflamed" -- with swelling and red, pink, or purplish coloring -- because cancer cells block lymph vessels in the skin. The skin may also have ridges or appear pitted like the skin of an orange.

There are also less common types of aggressive breast cancer, such as Paget disease (which starts in the milk ducts), angiosarcoma (which starts in the cells that line blood or lymph vessels), and Phyllodes tumor (which starts in the connective tissue).

What are the stages of breast cancer?

The evaluation of breast cancer is done by staging, based on the size of the tumor and extent of any spread. Staging questions that are asked to determine the severity of the cancer at diagnosis are:

• Has the cancer spread to nearby lymph nodes or other areas of the body?

• How likely is the tumor to spread and grow?

• Are certain biomarkers, such as ER, PR, and HER2 hormone receptors or other proteins, present in the cancer?

The TNM (tumor-nodes-metastasis) staging system will be applied to the cancer. TNM stages range from 0 to IV. Noninvasive, in situ cancer would be called stage 0, while stage IV would be cancer that has spread to other areas of the body.

Recurrent cancer refers to disease that returns -- either "locoregionally" (where the cancer started or in nearby lymph nodes) or distant (to other parts of the body).

What are the treatments for breast cancer?

Breast cancer treatments are generally determined by the type of cancer (i.e., receptor status) and stage.

The two main types of treatment options are:

• Local: surgery and/or radiation therapy
• Systemic: chemotherapy, hormone therapy, targeted-drug therapy such as anti-HER2 therapy, and immunotherapy

With surgery, the goal is to remove as much of the cancer as possible. Total removal of the breast is called mastectomy. Surgery may also be needed to remove lymph nodes in the breast area.

Lumpectomy (also called breast-conserving surgery) removes only the tumor and some surrounding healthy tissue (and often one or more lymph nodes in the armpit). Lumpectomy is often followed by radiation to help prevent the cancer from returning to the breast.

With radiation therapy, a radiation beam is targeted from outside the body to the area affected by the cancer. The extent of the radiation therapy will depend on how much of the breast tissue is involved in the cancer. The lymph nodes and chest wall may also require radiation therapy.

With chemotherapy, anti-cancer drugs are given either through injection into the vein (intravenously) or delivered by mouth (orally). Chemotherapy drugs then travel through the blood stream and into the cancer.

With endocrine therapy (also sometimes called hormone therapy), cancer cell proteins are prevented from attaching to hormones and using them to grow.

The NCI defines targeted-drug therapy (also called molecularly targeted therapy) as treatment that uses drugs or other substances to target specific molecules that cancer cells need to survive and spread. Some targeted therapies stop cancer cells from growing by interrupting signals that cause them to grow and divide, stopping signals that help form blood vessels, delivering cell-killing substances to cancer cells, or starving cancer cells of hormones they need to grow.

Other targeted therapies help the immune system kill cancer cells or directly cause cancer cell death. Most targeted therapies are either small-molecule drugs or monoclonal antibodies.

Immunotherapy will boost a person's own immune system to effectively recognize and destroy cancer cells. Immunotherapy is used in triple-negative breast cancer.

Treatment may involve a combination of all or some of these therapies. Patients may receive treatment before surgery (known as neoadjuvant therapy) and/or after surgery (known as adjuvant therapy).

All breast cancer treatments have side effects associated with them, but they will differ depending on the type of treatment.

Can men and children get breast cancer?

Men can get breast cancer, sometimes for the same reason as women (family history, older age, genetic mutations). Men with breast cancer usually have lumps in the breast and chest area that can be felt manually. Staging and treatment are similar in women and men. As male breast cancer is rare and accounts for only approximately 1% of all breast cancers, most of the treatment for men are extrapolated from the studies done in female breast cancer patients.

Less than 1% of breast cancer patients are younger than age 30 and the incidence of breast cancer in women younger than 20 is 1 in 1,000,000. A 2013 review noted that only 39 cases of primary breast cancer in pediatric patients have been published to date.

"Medical Journeys" is a set of clinical resources reviewed by physicians, meant for the medical team as well as the patients they serve. Each episode of this journey through a disease state contains both a physician guide and a downloadable/printable patient resource. "Medical Journeys" chart a path each step of the way for physicians and patients and provide continual resources and support, as the caregiver team navigates the course of a disease.