Mucinous Carcinoma of the Breast

Mucinous carcinoma of the breast — sometimes called colloid carcinoma — is a rare form of invasive ductal carcinoma (cancer that begins in the milk duct and spreads beyond it). Mucinous carcinoma of the breast accounts for about 2-3% of all breast cancer cases. In this type of cancer, the tumor is formed from abnormal cells that “float” in pools of mucin, a key ingredient in the slimy, slippery substance known as mucus.

Normally, mucus lines most of the inner surface of our bodies, such as our digestive tract, lungs, liver, and other vital organs. Many types of cancer cells — including most breast cancer cells — produce some mucus. In mucinous carcinoma, however, the mucus becomes a main part of the tumor and surrounds the breast cancer cells.

Mucinous carcinoma tends to affect women after they’ve gone through menopause. Some studies have found that the usual age at diagnosis is 60 or older.

Mucinous carcinoma is less likely to spread to the lymph nodes than other types of breast cancer. It’s also easier to treat.

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