Breast cancer

Breast cancer Classification and external resources
Mammogram showing breast cancer (indicated by arrow)
ICD-10	C50.
ICD-9	174-175,V10.3
OMIM	114480
DiseasesDB	1598
MedlinePlus	000913
eMedicine	med/2808 med/3287 radio/115 plastic/521
MeSH	D001943

Breast cancer is a cancer that starts in the cells of the breast in women and men. Worldwide, breast cancer is the second most common type of cancer after lung cancer (10.4% of all cancer incidence, both sexes counted) and the fifth most common cause of cancer death. In 2004, breast cancer caused 519,000 deaths worldwide (7% of cancer deaths; almost 1% of all deaths).

Classification

Breast cancers are described along four different classification schemes, or groups, each based on different criteria and serving a different purpose:

• Pathology - Each tumor is classified by its histological (microscopic anatomy) appearance and other criteria.
• Grade of tumor - The histological grade of a tumor is determined by a pathologist under a microscope. A well-differentiated (low grade) tumor resembles normal tissue. A poorly differentiated (high grade) tumor is composed of disorganized cells and, therefore, does not look like normal tissue. Moderately differentiated (intermediate grade) tumors are somewhere in between.
• Protein & gene expression status - Currently, all breast cancers should be tested for expression, or detectable effect, of the estrogen receptor (ER), progesterone receptor (PR) and HER2/neu proteins. These tests are usually done by immunohistochemistry and are presented in a pathologist's report. The profile of expression of a given tumor helps predict its prognosis, or outlook, and helps an oncologist choose the most appropriate treatment. More genes and/or proteins may be tested in the future.
• Stage of a tumor - The currently accepted staging scheme for breast cancer is the TNM classification. This considers the Tumor itself, whether it has spread to lymph Nodes, and whether there are any Metastases to locations other than the breast and lymph nodes.

Breast cancer is usually, but not always, primarily classified by its histological appearance. For example, inflammatory breast cancer (IBC), a form of ductal carcinoma or malignant cancer in the ducts, is distinguished from other carcinomas by the inflamed appearance of the affected breast.

Signs and symptoms

The first symptom, or subjective sign, of breast cancer is typically a lump that feels different from the surrounding breast tissue. According to the The Merck Manual, more than 80% of breast cancer cases are discovered when the woman feels a lump. Lumps found in lymph nodes located in the armpits and/or collarbone can also indicate breast cancer.

Indications of breast cancer other than a lump may include changes in breast size or shape, skin dimpling, nipple inversion, or spontaneous single-nipple discharge.

When breast cancer cells invade the dermal lymphatics—small lymph vessels in the skin of the breast—its presentation can resemble skin inflammation and thus is known as inflammatory breast cancer (IBC).

Occasionally, breast cancer presents as metastatic disease, that is, cancer that has spread beyond the original organ. Metastatic breast cancer will cause symptoms that depend on the location of metastasis. Bone or joint pains can sometimes be manifestations of metastatic breast cancer, as can jaundice or neurological symptoms.

Most symptoms of breast disorder do not turn out to represent underlying breast cancer. Benign breast diseases such as mastitis and fibroadenoma of the breast are more common causes of breast disorder symptoms.

Epidemiology and etiology

Today, breast cancer, like other forms of cancer, is considered to be the final outcome of multiple environmental and hereditary factors. Some of these factors include:

1. Lesions to DNA such as genetic mutations. Mutations that can lead to breast cancer have been experimentally linked to estrogen exposure. Beyond the contribution of estrogen, research has implicated viral transformation and the contribution of ionizing radiation in causing genetic mutations.
2. Failure of immune surveillance, a theory in which the immune system removes malignant cells throughout one's life.
3. Abnormal growth factor signaling in the interaction between stromal cells and epithelial cells can facilitate malignant cell growth. For example, tumors can induce blood vessel growth (angiogenesis) by secreting various growth factors further facilitating cancer growth.
4. Inherited defects in DNA repair genes, such as BRCA1, BRCA2 and p53.People in less-developed countries report lower incidence rates than in developed countries.

Experts believe that 95 percent of inherited breast cancer can be traced to one of two genes, which they call Breast Cancer 1 (BRCA1) and Breast Cancer 2 (BRCA2). Hereditary breast cancers can take the form of a site-specific hereditary breast cancer- cancers affecting the breast only- or breast- ovarian and other cancer syndromes. Breast cancer can be inherited both from female and male relatives.

Although many epidemiological risk factors have been identified, the cause of any individual breast cancer is often unknowable. Due to breast cancer is vary in different racial and ethnic group.

No etiology is known for 95% of breast cancer cases, while approximately 5% of new breast cancers are attributable to hereditary syndromes. In particular, carriers of the breast cancer susceptibility genes, BRCA1 and BRCA2, are at a 30-40% increased risk for breast and ovarian cancer, depending on in which portion of the protein the mutation occurs.

Worldwide, breast cancer is by far the most common cancer amongst women, with an incidence rate more than twice that of colorectal cancer and cervical cancer and about three times that of lung cancer. However breast cancer mortality worldwide is just 25% greater than that of lung cancer in women. In 2004, breast cancer caused 519,000 deaths worldwide (7% of cancer deaths; almost 1% of all deaths).

United States

Women in the United States have the highest incidence rates of breast cancer in the world; 141 among white women and 122 among African American women. Among women in the US, breast cancer is the most common cancer and the second-most common cause of cancer death (after lung cancer). Women in the US have a 1 in 8 (12.5%) lifetime chance of developing invasive breast cancer and a 1 in 35 (3%) chance of breast cancer causing their death. In 2007, breast cancer was expected to cause 40,910 deaths in the US (7% of cancer deaths; almost 2% of all deaths).Many doctors say that women exaggerate their risk of breast cancer.

UK

45,000 cases diagnosed and 12,500 deaths per annum. 60% of cases are treated with Tamoxifen, of these the drug becomes ineffective in 35%.

Prevention

Several factors can influence breast cancer incidence either positively or negatively.

Screening

Breast cancer screening is an attempt to find cancer in otherwise healthy individuals.

Genetic testing for breast cancer typically involves testing for mutations in the BRCA genes. This is not generally a recommended technique except for those at elevated risk for breast cancer.

Diagnosis

In a clinical setting, breast cancer is commonly diagnosed using a "triple test" of clinical breast examination (breast examination by a trained medical practitioner), mammography, and fine needle aspiration cytology.

Other options for biopsy include core biopsy, where a section of the breast lump is removed, and an excisional biopsy, where the entire lump is removed.

Staging

Breast cancer is staged according to the TNM system, updated in the AJCC Staging Manual, now on its sixth edition. Prognosis is closely linked to results of staging, and staging is also used to allocate patients to treatments both in clinical trials and clinical practice.

Approximately 90% of new breast cancer cases in the US will be classified as "early-stage" cases (DCIS, Stage I,IIA, IIB or IIIA), due to early detection and prevention techniques. Early-stage treatment options are different from late-stage options.

Hormone receptors

About two thirds of postmenopausal breast cancers are estrogen receptor positive (ER+) and progesterone receptor positive (PR+).

HER2

When activated in cancer cells, HER2 accelerates tumor formation. About 20-30% of breast cancers overexpress HER2.

Psychological aspects of diagnosis and treatment

Online cancer support groups are also very beneficial to cancer patients, especially in dealing with uncertainty and body-image problems inherent in cancer treatment.

Not all breast cancer patients experience their illness in the same manner. Premenopausal women with estrogen-receptor positive breast cancer must confront the issues of early menopause induced by many of the chemotherapy regimens used to treat their breast cancer, especially those that use hormones to counteract ovarian function.

As the incidence of breast cancer in women over 50 rises and survival rates increase, breast cancer is increasingly becoming a geriatric issue that warrants both further research and the expansion of specialized cancer support services tailored for specific age groups.

Metastasis

A micrograph showing breast cancer (dark pink) in and around a lymph node (purple).

Most people understand breast cancer as something that happens in the breast. H

When breast cancer is found in bones, it has usually spread to more than one site. This important finding could potentially alter the way in which breast cancer is treated.

History

Breast cancer may be one of the oldest known forms of cancerous tumors in humans. The oldest description of cancer was discovered in Egypt and dates back to approximately 1600 BC.

Prominent women who died of breast cancer include Empress Theodora, wife of Justinian; Anne of Austria, mother of Louis XIV of France; Mary Washington, mother of George, and Rachel Carson, the environmentalist.

Cultural references

In the month of October, breast cancer is recognized by survivors, family and friends of survivors and/or victims of the disease. A pink ribbon is worn to recognize the struggle that sufferers face when battling the cancer.

The pink and blue ribbon was designed in 1996 by Nancy Nick, President and Founder of the John W. Nick Foundation to bring awareness that "Men Get Breast Cancer Too!"

Gallery

Breast self exam





Illustration of the early warning signs of breast cancer







Woman undergoing mammogram




Mammography pictures, normal (left) and cancerous (right)

Mammogram displaying breast cancer, indicated with an arrow Breastcancer in ultrasound Mastectomy patient Breast prostheses used by some mastectomy patients
Patient with advanced local-regional recurrence of breast cancer with an ulcerating axillary mass Mastectomy specimen containing a very large cancer of the breast (in this case, an invasive ductal carcinoma) Typical macroscopic (gross) appearance of the cut surface of a mastectomy specimen containing a cancer, in this case, an invasive ductal carcinoma of the breast, pale area at the center Excised human breast tissue, showing a stellate area of cancer 2cm in diameter. The lesion could be felt clinically as a hard mobile lump, not attached to skin or chest wall.
Benign granular cell tumor removed from a woman's breast. Granular cell tumors of the breast represent one of the few lesions that can impersonate an invasive breast cancer on gross examination. Infiltrating ductal carcinoma of the breast Infiltrating ductal carcinoma of the Breast assayed with anti Mucin 1 antibody Breast cancer (Infiltrating ductal carcinoma of the breast) assayed with anti HER-2 (ErbB2) antibody
Invasive lobular carcinoma of the breast demonstrating a predominantly lobular growth pattern Metaplastic(sarcomatoid) carcinoma of the breast. Histopathologic image from ductal cell carcinoma in situ (DCIS) of breast. Hematoxylin-eosin stain. Histopathology of invasive ductal carcinoma of the breast representing a scirrhous growth. Core needle biopsy. HER-2/neu oncoprotein expression by Ventana immunostaining system.