SNP Shot: Genomic Insights

Breast cancer occurs when breast cells become abnormal and multiply uncontrollably, forming a tumor. While much more prevalent in women, men can also develop this cancer. The most common type in both sexes is ductal cancer, originating in the cells lining the milk ducts. Women can also develop lobular cancer, which begins in the milk-producing glands. Because men possess little or no lobular tissue, lobular cancer is rare in men.

Early breast cancer typically doesn't cause pain and may be asymptomatic. As it progresses, signs can include a lump or thickening in or near the breast, changes in breast size or shape, nipple discharge, tenderness, or retraction, and skin irritation, dimpling, redness, or scaliness. However, these symptoms can be associated with other conditions, and their presence doesn't definitively indicate breast cancer.

Invasive breast cancer occurs when cancerous cells spread to surrounding breast tissue. If the cancer metastasizes, it often spreads to the bones, liver, lungs, or brain. Metastatic cancers are tumors that originated in one location and spread to other parts of the body.

A small percentage of breast cancers are hereditary, occurring in families due to inherited gene mutations. These cancers tend to develop earlier in life than non-inherited (sporadic) cases, and are more likely to develop in both breasts.

Inheritance:

The majority of breast cancer cases are not hereditary, resulting from somatic mutations acquired during a person's lifetime, and do not cluster in families. In hereditary breast cancer, the inheritance pattern depends on the specific gene involved. For example, BRCA1 and BRCA2 gene mutations follow an autosomal dominant pattern, where one copy of the altered gene is sufficient to increase cancer risk. While breast cancer is more common in women, the mutated gene can be inherited from either parent. Similarly, the other syndromes mentioned exhibit autosomal dominant inheritance. Importantly, individuals inherit an increased susceptibility to cancer, not the disease itself. Not everyone with these gene mutations will develop cancer. In many familial breast cancer cases, the genetic basis and inheritance mechanism remain unclear.