BREAST CANCER

Breast cancer is the most common of all cancers and is the leading cause of cancer deaths in women worldwide, accounting for >1.6% of deaths and case fatality rates are highest in low-resource countries. A recent study of breast cancer risk in India revealed that 1 in 28 women develop breast cancer during her lifetime. This is higher in urban areas being 1 in 22 in a lifetime compared to rural areas where this risk is relatively much lower being 1 in 60 women developing breast cancer in their lifetime. In India the average age of the high risk group in India is 43-46 years unlike in the west where women aged 53-57 years are more prone to breast cancer.


RISK FACTORS
The risk factors influencing breast cancer risk are broadly classified into modifiable and non –modifiable factors. The non modifiable risk factors are age, gender, number of first degree relatives suffering from breast cancer, menstrual history, age at menarche and age at menopause. While the modifiable risk factors are BMI, age at first child birth, number of children, duration of breast feeding, alcohol, diet and number of unsuccessful pregnancies ( abortions).


SCREENING
Women with a higher than average risk of developing breast cancer may be offered screening and genetic testing for the condition. NHS Breast Screening Programme recommends that women between 50-70 years of age of should be screened once every three years. Screening is especially recommended for women with risk factors, a significant one being family history. Having a 1st-degree relative (mother, sister, and daughter) with breast cancer doubles or triples the risk of developing the cancer. About 5% of women with breast cancer carry a mutation in one of the 2 known breast cancer genes, BRCA1 or BRCA2. If relatives of such a woman also carry the gene, they have a 50 to 85% lifetime risk of developing breast cancer. Heightened awareness of breast cancer risk in the past decades has led to an increase in the number of women undergoing mammography for screening, leading to detection of cancers in earlier stages and an improvement in survival rates. Approximately 20% of the cancers detected in a given year will be missed at the screening, but will become clinically evident in the period before the next screen (interval cancers).


PATHOLOGY
The various abnormalities of the breast include nipple discharge, inflammations, ANDI , benign disorders, phyllodes / sarcomas and carcinoma Most breast cancers are epithelial tumors that develop from cells lining ducts or lobules; less common are nonepithelial cancers of the supporting stroma (eg, angiosarcoma, primary stromal sarcomas, phyllodes tumor). Cancers are divided into carcinoma in situ and invasive cancer. Paget's disease of the nipple is a form of ductal carcinoma in situ that extends into the overlying skin of the nipple and areola, manifesting with an inflammatory skin lesion and may become invasive.
The pathological variations of breast cancer influence the prognosis. In situ cancers (DCIS/LCIS) are slow growing, indolent tumors. Autopsy studies have indicated that the incidence of DCIS in asymptomatic women ranges from .02% to 18.2% indicating that some DCIS do not become evident during a women’s lifetime. Invasive carcinoma is primarily adenocarcinoma. About 80% is the infiltrating ductal type; most of the remainder is infiltrating lobular. The pathological variants with a favorable prognosis are tubular, cribriform, mucinous and adenoid cystic variants, while intermediate prognosis is seen with medullary, secretory and invasive lobular cancers. The most unfavorable pathology is high grade metaplastic, micropalliary, signet ring cell morphology, inflammatory cancer.


PATHOPHSIOLOGY
Breast cancer invades locally and spreads initially through the regional lymph nodes, bloodstream, or both. Metastatic breast cancer may affect almost any organ in the body—most commonly, lungs, liver, bone, brain, and skin.


SYMPTOMS AND SIGNS
Most breast cancers present as


• a lump felt by the patient or during routine physical examination or mammography.


• Less commonly, the presenting symptom is thickening in the breast. Paget's disease of the nipple presents with skin changes, including erythema, crusting, scaling, and discharge.


• A few patients with breast cancer present with signs of metastatic disease (eg, pathologic fracture, pulmonary dysfunction).


During a physical examination a lump is felt distinctly different from the surrounding breast tissue. More advanced breast cancers are characterized by fixation of the lump to the chest wall or to overlying skin, by satellite nodules or ulcers in the skin. Matted or fixed axillary lymph nodes suggest tumor spread. Inflammatory breast cancer is characterized by diffuse inflammation and enlargement of the breast, often without a lump, and has a particularly aggressive course.

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