An Overview of Symptoms

Breast cancer is a disease in which cells in the breast grow out of control. There are many different types, and they are determined by which cells in the breast become cancerous. Breast cancer can create tumours that cause palpable lumps or swaths of cancer that cause thickening. Both presentations can create a heavy feeling or other symptoms in the breast like inflammation, swelling, dimpling, distortions, orange peel skin, scaliness and/or ulcers of the breast or nipple, itching and pain, nipple changes like turning inward or pulling/changing direction, nipple discharge, or a change in breast shape which can all be symptoms of the disease (Torrado, 2025; WHO, 2024). 

Anatomy of the Breast

The breasts overlay your pectoral (chest) muscles and are made up of three main parts: lobules, ducts, and connective tissue. The lobules are the glands that produce milk. The ducts are the tubes that carry milk to the nipple, and the connective tissue (which consists of fibrous and fatty tissue) surrounds these nipple organs and holds everything together (CDC, 2024; Menon et al., 2024; WHO, 2024). Though men do still have lobule glands, only women have fully developed lobules (CDC, 2024; Torrado, 2025; WHO, 2024). Breasts also contain lymph nodes, small, bean-shaped organs that help transport immune cells and remove waste from tissue. Breast cancer cells most commonly begin inside these milk ducts and/or the milk-producing lobules of the breast, but not always.

Understanding Breast Cancer’s Origins and Terminology

Most breast cancers begin in the ducts or lobules, but there are some types with other origins. Breast cancer can be “In Situ”, an early precancerous condition that is not life-threatening, where abnormal cells are present in its origin spot. It can be “Invasive”, meaning it has spread outside of this origin into surrounding tissues in or very near the origin spot, or it can be “Metastatic”, meaning it has spread outside the breast through blood and lymph vessels to other parts of the body; sometimes locally (to organs or tissue near the original location), sometimes distantly (to organs or tissues further away from the origin site. When breast cancer spreads to other parts of the body, it has “metastasized”. At that point, depending on where it goes, it can (though does not always) become a life-threatening situation (CDC, 2024).

Statistics and Gender Facts

Breast cancer is the most common cancer diagnosed in women, accounting for more than 1 in 10 new cancer diagnoses annually, and is the second most common cause of cancer death among women worldwide (Menon et al., 2024). But everyone, regardless of biological sex, has at least a small amount of breast tissue, and both sexes possess lymphatic and vascular systems, and nipples. Both men and women can get breast cancer (Cancer Research UK, 2023; CDC, 2024; Menon et al., 2024; National Cancer Institute & PDQ Editorial Boards, 2025; Torrado, 2025; WHO, 2024), but breast cancer in general is about 100 times more common in women (CDC, 2024).

The most common type of breast cancer, accounting for approximately 80-85% of all breast cancers, is ductal carcinoma (Shockney, 2025). It begins in the lining of the milk ducts (thin tubes that carry milk from the lobules of the breast to the nipple). The second most common type of breast cancer, accounting for 10-15% of all breast cancers, is lobular carcinoma (CDC, 2024; Torrado, 2025). This type begins in the lobules (milk glands) of the breast and is less common in men (Cancer Research UK, 2023). Lobular breast cancer has unique and unusual characteristics that make it harder to detect in imaging scans and it is commonly diagnosed at more advanced stages than the more common ductal cancer. It is less likely than the ductal cancers to make solid tumors and tends to spread out in lines, or in a marbling pattern in the tissue. It is less responsive to chemotherapy and it is also more likely to show up in both breasts (Cancer Research UK, 2023; Torrado, 2025).

Both ductal and lobular breast cancer can be driven by hormones, the HER2 protein, or can be triple negative, meaning it isn't driven by any of these common drivers, and some can be driven by genetic mutations (Cancer Research UK, 2023; CDC, 2024; Menon et al., 2024; National Cancer Institute & PDQ Editorial Boards, 2025; Shockney, 2025; Torrado, 2025; WHO, 2024). Other, rare types of breast cancer that also begin in the ducts but have other features and account for only 1-5% of breast cancer cases are: medullary, mucinous, tubular, adenoid cystic carcinoma, metaplastic, and papillary. (Cancer Research UK, 2023; Menon et al., 2024). Inflammatory breast cancer is also a type of ductal cancer within this statistial category, but its symptoms, outlook and treatment are different. It is always stage three because it involves the skin (ACS, 2025). The ductal breast cancer subtypes are more common in men (CDC, 2024).

Basal-type breast cancer can start in either or both the outer layer of the ducts and/or milk lobes in the basal membrane and is very commonly triple negative, although not exclusively triple negative. Men can get this subtype, but it is less common. (Cancer Research UK, 2023).

Cystosarcoma phyllodes, also known as phyllodes tumor, is a rare breast tumor that grows quickly and can be either benign (non-cancerous), malignant (cancerous), or borderline. These tumors develop in the connective tissue of the breast and are characterized by a "leaf-like" pattern of growth. Cystosarcoma phyllodes are driven by a complex interplay of factors, including injury to the breast, hormonal influences, cell signaling pathways, vascular factors, angiogenesis, genetic mutations, and Li-Fraumeni syndrome, which is a hereditary disorder that is linked to an increased risk of phyllodes tumors. While the exact cause is not fully understood, several mechanisms are thought to play a role in their development. Sporadic cases have been reported in males, often in association with gynecomastia (enlarged breast tissue). These tumors can occur at any age, but are most commonly seen in middle-aged individuals (Cancer Research UK, 2023; Torrado, 2025).

Breast lymphoma, specifically primary breast lymphoma, originates in the breast's lymphatic tissue, not the breast tissue itself. It occurs in both sexes, but is a rare occurrence in men (Ha et al., 2013).

Angio Sarcomas of the breast start in the cells that make up the walls of the blood or lymphatic vessels and can be primary or secondary (Cancer Research UK, 2023), and can occur spontaneously or be associated with exposure to radiation therapy or chronic lymphedema (An et al., 2024). This can occur in both sexes, although it is more rare in men.

Paget's disease of the breast is a rare condition of the nipple that is often mistaken for mastitis, eczema, or dermatitis. This condition develops in the nipple or the areola and is a sign that there may be breast cancer in the tissues behind the nipple. It is possible to have Paget’s disease of the breast with no underlying cancer, but this is less common. About half of the people diagnosed with Paget's disease of the breast have a lump behind the nipple, and most people with a lump behind the nipple are found to have invasive breast cancer, and both women and men can develop it. (Cancer Research UK, 2023).

Luminal Subtyping

In pathology reports, it is common to see the labels Luminal A or B alongside a cancer diagnosis. Luminal A and B are two molecular subtypes of breast cancer within the broader category of hormone receptor-positive (HR+) breast cancer. These subtypes are differentiated based on factors like the presence of the HER2 protein, Ki-67 (a biomarker that measures cell proliferation) expression levels, and other molecular markers. Luminal A is typically HER2 negative with a low Ki67, usually <14%, while Luminal B can be either HER2 positive or negative with a higher ki67 usually > or = to 14% (Inic et al., 2014).

Grading, Ploidy, and Cell Proliferation

When cancer cells are biopsied, the lab gives them a grade. This grade reflects how similiar in appearance the cancer cells are to normal cells. It is used to help predict your outcome and to help figure out what treatments might work best.

The term Ploidy, refers to the amount of DNA that cancer cells contain. This does not usually influence treatment plans. Cell proliferation though, does impact treatment and is measured by the Ki-67. A higher Ki-67 implies a more aggresive cancer.

*additional reading provided at underlined links