Breast cancer is the second most common type of cancer in women. This type of cancer can occur in men, but is rare. The CDC notes that while breast cancer occurrence rates remained more or less level from 2003 – 2012, overall survival rates have improved. New research, increased public awareness, and advancing treatment methods have all contributed to this statistic.
The human breast is made of ducts, lobules, connective tissue, and fatty tissue. Breast cancer occurs when cancerous cells develop in ducts or lobules of the breast. These cells grow out of control and may form tumors. If left untreated, breast cancer can metastasize (spread) to other parts of the body.
Breast cancer can occur in men and women, but is far less common in men. According to the American Cancer Society, men are at a lifetime risk of 1 in 1,000 of developing breast cancer while a woman’s lifetime risk is 1 in 8.
There are several different types of breast cancer. The exact type is determined by where the cancer is located and the tissues where it forms. Most breast cancers are classified as carcinomas, which means that they start in the cells that form the lining of the breast. In some cases, a single breast tumor may actually be several types of cancer such as a mixture of invasive and in situ cancers. The most common types of breast cancer are listed below.
Ductal Carcinoma In Situ is the most common type of pre-invasive or non-invasive breast cancer. Cancerous cells have developed in the lining of the ducts, the passageways which connect the lobes to the nipples, but have not spread to other parts of the breast.
Key points about DCIS:
Invasive Ductal Carcinoma is the most common type of invasive breast cancer, making up about 80% of all cases in the US. This type of cancer starts in the ducts, or tubes, that carry milk from the lobes to the nipple. Unlike ductal carcinoma in situ, the cancerous cells then spread beyond the walls of the ducts into surrounding tissue. About 80%, or 8 in 10 cancers, are IDCs.
Lobular carcinoma in situ begins in the glands (lobes) within the breast that produce milk. However, the cancerous cells are contained within the walls of the lobes and do not spread.
Key points about LCIS:
Much like lobular carcinoma in situ, invasive lobular carcinomas start in the glands (lobes) within the breast that produce milk. These become invasive when they spread past the lobes and into surrounding tissue. About 10%, or 1 in 10 cancers, are Invasive Lobular Carcinomas.
In addition to the most common types of breast cancer, there are several less common types.
Inflammatory breast cancer is a rare and aggressive type of breast cancer, occurring in only 1 – 3% of cases. This type of breast cancer has a high chance of metastasizing (spreading) to other parts of the body.
Inflammatory breast cancer is characterized not by a lump, but by redness and swelling in the breast. The skin may also appear thick or pitted. Symptoms may develop quickly and can worsen within days.
Paget disease of the nipple is a rare type of breast cancer that occurs in 1% of all breast cancers. This cancer starts in the breast ducts and spreads to the nipple.
This type of cancer is characterized by the skin on the nipple nipple and areola appearing scaly, red, and irritated. Bleeding or oozing in the area may also occur.
Phyllodes tumors make up less than 1% of all breast tumors. Unlike carcinomas, which start in the linings of tissues, a phyllodes tumor develops in the connective tissues of the breast.
Although these tumors grow quickly, they rarely spread beyond the breast. They are usually benign but can sometimes be malignant. Surgery is usually required to remove these tumors in order to prevent recurrence.