Breast cancer is carcinoma of the breast, usually in the female. One in three women who live to 85 will have cancer, with breast cancer affecting one in three of those, for a total lifetime risk of one in nine. In 2001, there were 20 400 new breast cancer cases in Canada, with an average rise in incidence of 0.7% per year. Breast cancer is a "good prognosis" tumor, with a five year over all survival of 81%, and a lifetime survival of 66%. The staging or tumor and node status at diagnosis are the most important predictors of survival.
Risk factors for the development of breast cancer are age, family history, a previous history of breast cancer, breast density greater than 75%, previous exposure to high dose radiation, early menarche, late menopause, the use of exogenous hormones, or being nulliparous. 5% of all breast cancers have an identifiable genetic component, with the BRCA1 and BRCA2 as the best known.
Breast screening is used in an attempt to intercept breast cancer before it turns into metastatic disease. Women at low risk below the age of 50 are not routinely screened. Women aged 50-74 at low risk receive biannual mammogram and a yearly breast examination.
If the woman is at a high risk for breast cancer, then screening should happen annually. A woman is high risk if one first degree relative under 50 has breast cancer, two first degree relatives have had breast cancer at any age, one first degree relative has ovarian cancer, or the patient has a personal history of ovarian cancer.
Also, pathologic diagnosis of atypical ductal or lobular hyperplasia or lobular carcinoma in situ and a breast density greater than 75% put a woman at high risk.
Any palpable cancer is a late-stage cancer. If a woman reports a palpable mass, physical examination should occur, followed by a diagnostic mammogram and ultrasound. If the mass is cystic, observation or aspiration are indicated. If the mass is solid, observation or biopsy are indicated. Biopsy can be done by fine needle aspiration or open core biopsy.
If there is a non-palpable abnormality, it must be localized, which is first attempted by ultrasound (and a biopsy taken if it is suspicious). If the abnormality cannot be localized with ultrasound, stereo tactic views are attempted with computer generated 3D images.
The TNM (tumor, nodes, metastasis) system of staging is now used for staging, making it possible to draw comparisons in studies internationally.
Breast Conserving Therapy (BCT) is the standard of care in women with breast cancer. This involves local excision of the tumor, with preservation of the breast. Combined BCT and local radiation gives equivalent survival results when compared to modified radical mastectomy.
Contraindications for BCT are a tumor bigger than 5cm, incomplete tumor removal, a small breasted woman where the cosmetics are not acceptable, a tumor under the nipple, a multicentric tumor, or a previous contra-lateral mastectomy.