Only a very small percentage of people who are diagnosed with breast cancer have a rare type. Having a rare type does not mean that survival is worse. In fact, many have a better general prognosis than more common types. The outcome of breast cancer depends on many factors including tumor size, whether the cancer has spread to the lymph nodes under the arm, how poorly differentiated (or “wild looking”) the cells are compared with normal cells under the microscope, and how many and how fast the cancer cells are dividing. A breast cancer diagnosis is unique to each person. While there are general categories, it's important to speak with your health care team to determine your special circumstances.
Paget's Disease
Paget’s disease is rare, affecting less than 3% of all breast cancer patients. It presents as itchiness and scaling on the nipple, which is caused by cancer cells growing into the nipple skin. The disease can spread gradually into the areola and breast from the milk ducts that drain out to the nipple.
Paget’s disease is commonly mistaken for eczema. Eczema is a fairly harmless skin condition that is far more common than Paget’s disease. If you notice persistent skin irritation that does not heal, see your doctor for a professional diagnosis.
There are two variants of Paget’s disease. The first has an associated breast mass that can be invasive. In this case, treatment is the same as it is for invasive breast cancer.
The other variant is ductal carcinoma in situ and involves just the nipple-areola complex. In this case, the cancer is not as aggressive and rarely spreads to the lymph nodes.
Tubular Carcinoma
Tubular carcinoma is a type of invasive ductal carcinoma (IDC). Its distinguishing feature is the visual appearance of the cells under a microscope. In this case, the cancer cells resemble tiny tubes that are well differentiated, meaning the cells are more like normal cells than poorly-defined ones.
This type of breast cancer accounts for no more than 2% of all breast cancer diagnoses and occurs most frequently in women who are in their 50s.
Tubular breast carcinoma tends to be small, highly estrogen dependent and HER2/neu negative. Women with this type of breast cancer are less likely to metastasize and have an excellent survival rate.
Medullary Carcinoma
Medullary carcinoma is a kind of invasive ductal carcinoma (IDC) named for its similarity in color to brain tissue (the medulla). The cells are often poorly differentiated, which means that they look less like normal cells than well-defined ones.
This type of breast cancer accounts for as much as 7% of all breast cancer diagnoses and occurs most frequently in women in their late 40s and early 50s.
Medullary carcinoma is often difficult to diagnose. It tends to be of high grade, but has a better prognosis than other breast carcinomas. Lymph node involvement tends to be less frequent and the 1-year survival rate is as high as 92%.
Mucinous Carcinoma
Mucinous carcinoma (also known as colloid) is a type of invasive ductal carcinoma (IDC). Its distinguishing feature is mucous production. Within the mucous are cancerous cells that are often poorly differentiated, which means that the cells look less like normal cells than well-defined ones.
This type of breast cancer accounts for no more than 3% of all breast cancer diagnoses and occurs most frequently in women in their 60s. Most often, mucinous carcinoma is characterized by tumors that can be felt. It tends to be highly estrogen dependent, HER2/neu negative and seldom involves lymph nodes.
Although mucinous carcinomas can grow very large, women with this diagnosis have a ten-year survival rate of more than 90%.
Papillary Carcinoma
Invasive papillary carcinoma makes up approximately 3% of all breast cancer diagnoses. It occurs most frequently in postmenopausal women and disproportionately in non-white women. More than 75% of the cases include a ductal carcinoma in situ (DCIS) component.
The main difference between papillary and other breast cancers is the appearance of the cells when you look at them under a microscope. The cells stick out in little papules, or fingerlike projections. In a thir of papillary carcinoma cases, the cancer spreads to the lymph nodes. Overall, it has a better prognosis than other, more common breast cancers.
Metaplastic Carcinoma
Metaplastic carcinoma grows at a relatively rapid rate and is rare, accounting for approximately 0.3% of all breast cancers. It represents a group of invasive breast cancers where a portion of the tumor's cells transforms into an alternate cell type. On average, patients with this disease are about a year and a half older than those with other breast cancers, are more likely to be African-American, have larger tumors with more abnormal cells at diagnosis. These patients are more likely to have estrogen-negative tumors and negative axillary (arm pit) lymph nodes.
The prognosis for metaplastic carcinoma patients is similar to that of those who have invasive cancers that don't fall under a specific category.
Phyllodes Tumors
Phyllodes tumors, also called phylloides tumors or cystosarcoma phyllodes, make up nearly 0.5% of breast tumors. They can be benign (non-cancerous), borderline or malignant. Even on imaging and tissue sampling, they resemble fibrous tumors, which are more common in younger rather than older women. Pyllodes tumors tend to appear in a woman's 40s, about a decade later than women typically diagnosed with lumps you can feel. Those with benign phyllodes are generally younger than those diagnosed with malignant phyllodes. The tumors usually grow rapidly and reach a large size. They have a high recurrence rate, yet are unlikely to metastasize to the axillary (arm pit) lymph notes.
This article has been republished with the permission of Breast Cancer Network of Strength
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