Although breast cancer is often referred to as one disease, there are, in fact, many types of breast cancer. These vary in cellular type and location. The type of breast cancer you have often affects your prognosis.
Ductal carcinoma in situ (DCIS, non-invasive breast cancer) and invasive breast cancers
Ductal carcinoma in situ (DCIS) is a non-invasive breast cancer. “In situ” means "in place". With DCIS, the abnormal cells are contained in the milk ducts of the breast and have not spread to nearby breast tissue. (For more on breast structure, see Figure 1.1.) Learn more about DCIS.
Invasive breast cancer has spread from the original site (either the milk ducts or the lobules) into the nearby breast tissue and possibly into the lymph nodes and/or other parts of the body. For this reason, invasive breast cancers have a poorer prognosis than ductal carcinoma in situ.
By using a microscope to look at the tissue removed during a biopsy, a pathologist can determine whether the tumor is ductal carcinoma in situ or invasive breast cancer. He/she can also classify the tumor into different subgroups, such as tumor grade.
Types of invasive breast cancer
Figure 4.6 lists the types of invasive breast cancer. The most common type of invasive cancer is invasive ductal carcinoma (also called infiltrating ductal carcinoma). Invasive ductal carcinoma accounts for 50 to 75 percent of all breast cancer cases. Invasive lobular carcinoma is the next most common type and accounts for about five to 10 percent of cases. Three rare types of breast cancer known for their good prognosis are mucinous (colloid) carcinoma, papillary carcinoma and tubular carcinoma (which has a very good prognosis). Together, however, these three types account for only about five percent of all breast cancers cases [8,17].
Figure 4.6: Prevalence and Tumor Characteristics for Different Types and Special Forms of Invasive Breast Cancer
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Types of Invasive Breast Cancer
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Proportion of All Invasive Cancers
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Tumor Characteristics
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Prognosis
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Invasive ductal carcinoma (IDC)
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50-75%
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- Hard tumor texture
- Tumor is irregular, star-shaped
- Cell features vary
- DCIS often present
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- Prognosis varies with stage and grade of tumor
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Invasive lobular carcinoma (ILC)
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5-10%
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- Normal, slightly firm or hard tumor texture
- Cells appear in single file order
- Tumors are most often ER-positive and HER2/neu-negative
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- Prognosis varies with stage and grade of tumor
- For any given stage or grade, prognosis is similar to that of IDC
- Pattern of metastases is slightly different from IDC (more likely to go to the gastrointestinal tract)
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Medullary carcinoma
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<2%
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- Soft tumor
- Cells have a sheet-like appearance
- Tumors are often ER-negative
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- More common among younger women and women with a BRCA1 genetic mutation
- At this time, it is not known whether prognosis is better than or similar to that for IDC and ILC
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Mucinous (colloid) carcinoma
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<5%
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- Soft tumor
- Often no palpable tumor
- Cells are surrounded by excess mucous (mucin)
- Tumors are most often ER-positive and HER2/neu-negative
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- More common among older women
- More favorable prognosis
- Lymph node involvement is less common
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Papillary carcinoma
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<1-2%
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- Soft tumor
- Cells appear as fingerlike branches
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- More common among postmenopausal women
- More favorable prognosis
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Tubular carcinoma
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1-3%*
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- Tumors are most often small
- Often no palpable tumor
- Cells form tube-like structures
- Tumors are most often ER-positive and HER2/neu-negative
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- Prognosis is most often much better than IDC (survival at 5 years is 88%)
- Metastases and lymph node involvement are rare
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Special Forms of Invasive Breast Cancer
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Inflammatory breast cancer (IBC)
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1-5%
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- Often no palpable tumor
- Clusters of cancer cells block the breast lymphatic system
- Symptoms include reddening or thickening of the skin of the breast
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Paget's disease
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1-3%
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- Most often related to existing invasive cancer or DCIS
- Symptoms include red, scaly or irritated skin in the nipple area
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- Prognosis varies with stage of tumor
- Those who have a mass at time of diagnosis most often have more advanced breast cancer
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* Percentage is higher in cancers found through mammography screening.
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Adapted from Dillon, Guidi and Schnitt, 2010 [17], Hansen, 2010 [18] and Merajver, Iniesta and Sabel, 2010 [19].
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Special forms of breast cancer
Though they are not specific types of tumors, there are some special forms of breast cancer. Two of those are: inflammatory breast cancer (IBC) and Paget's disease of the nipple.
Inflammatory breast cancer (IBC)
Inflammatory breast cancer (IBC) is a rare and aggressive form of invasive breast cancer. It is called inflammatory breast cancer because its main symptoms are swelling (inflammation) and redness of the breast. The skin on the breast may appear dimpled, like the skin of an orange and may be warm to the touch [19]. Because of its symptoms and the frequent lack of a lump, IBC may first be treated as an infection.
With other forms of breast cancer, symptoms may not occur for years. However, with IBC, symptoms tend to arise within weeks or months. Routine mammography can miss this cancer because of its rapid onset. IBC can also be hard to see on a mammogram because it is often spread throughout the breast. However, skin changes or a mass may be noted during a clinical exam. The average age of diagnosis of IBC is slightly younger than the age of diagnosis of other forms of breast cancer [19]. For more on IBC, see the Treatment section.
Paget's disease of the nipple
Paget's disease of the nipple is usually, but not always, found with breast cancer. When cancer is present, the tumor grows from underneath the nipple and then breaks out onto the surface of the nipple. Paget's can be related to invasive breast cancer or DCIS. Symptoms include itching, burning, redness and scaling of the skin on the nipple and areola. There may also be a bloody discharge from the nipple, and the nipple may appear flattened against the breast [18]. Paget's can be diagnosed from a biopsy of the skin or nipple, or may be found when an underlying cancer is diagnosed. Treatment and prognosis depend on the underlying cancer [18].
Metaplastic breast cancer
Metaplastic breast cancer is a rare form of invasive ductal carcinoma (IDC), accounting for fewer than five percent of all invasive breast cancers [17]. Compared to more common types of breast cancer, metaplastic tumors tend to be larger, have a higher tumor grade and be estrogen receptor-negative. Because metaplastic tumor cells have a variety of forms, these cancers can be hard to diagnose and are often confused with breast sarcomas (another rare diagnosis). It is best if the pathology slides are sent out for review to confirm the diagnosis. You can request that your health care provider send the slides out for review or you may wish to seek a second opinion for confirmation. Learn more about breast pathology practices.
Other types of cancer that occur in the breast
Most cancers that occur in the breast are breast cancers (breast carcinomas). However, in rare cases, other types of cancer such as lymphomas (cancer of the lymph system) and sarcomas (cancer of muscle tissue) can occur in the breast. For example, although Phyllodes tumors occur in the breast, they are sarcomas rather than carcinomas. Other types of cancer in the breast can be benign (non-cancerous) or malignant (cancerous). Although local recurrence is common, metastases are rare. Because these cancers are not carcinomas, they are treated differently and have different risk profiles than breast cancer. For more information on Phyllodes tumors and lymphomas, visit the National Cancer Institute's Web site.
Updated 10/26/09
