Invasive Breast Cancer - What Is It?

"Invasive" cancer has spread beyond the breast's ducts or lobes and has gotten into other tissues inside the breast. It is more serious than non-invasive cancers because it can spread cancer cells throughout the entire body via the lymphatic system and bloodstream. According to the American Cancer Society, more than 180,000 women in the United States find out they have invasive breast cancer every year.

There are two types of invasive breast cancer: Invasive Ductal Carcinoma and Invasive Lobular Carcinoma.

Invasive ductal carcinoma (IDC) is the most common type of breast cancer. It starts in the milk ducts. About 80% of all breast cancers are this kind. Invasive ductal carcinoma also affects men.

There are some types of IDC that happen less frequently. These cancer cells look and behave somewhat differently than typical invasive ductal carcinoma cells do.

• Tubular carcinoma of the breast accounts for about 1-2% of all breast cancer cases. The tumor is usually small and made up of tube-shaped cells that are "low grade” which means they look similar to normal, healthy cells and tend to grow slowly. Tubular carcinoma of the breast is less likely to spread outside the breast than other types of breast cancer. It’s also easier to treat. Studies have found that the average age of diagnosis for tubular carcinoma ranges from the mid-40s to late 60s.


• Medullary carcinoma accounts for about 4% of all cases of breast cancer. It is called “medullary” carcinoma because the tumor is a soft, fleshy mass that is shaped like a part of the brain called the medulla. It usually affects women in their late 40s or early 50s. It tends to be more common in women with a BRCA1 mutation. It is also more common in Japan than in the United States. These cells look like aggressive, highly abnormal cancer cells, but they don’t act like them. Because they do not grow quickly, the cancer is usually found and treated before it has spread outside the breast to the lymph nodes. For this reason, it’s typically easier to treat than other types of breast cancer.


• Mucinous or Colloid carcinoma accounts for about 2-3% of all breast cancer cases. The tumor is formed from abnormal cells that “float” in pools of mucus that becomes part of the tumor itself. This kind tends to affect women after they’ve gone through menopause. It is less likely to spread to the lymph nodes than other types of breast cancer and is also easier to treat.


• Invasive Papillary carcinomas occur in about 1% of all invasive breast cancers. In most cases it is found in women who have already been through menopause. This type of tumor usually has a well-defined border and is made up of small, finger-like projections. In most cases of invasive papillary carcinoma, ductal carcinoma in situ is also present.


• In invasive cribriform carcinoma, the cancer cells have gone into the surrounding breast tissue in nestlike formations between the ducts and lobules. Within the tumor, there are distinctive holes in between the cancer cells, making it look something like Swiss cheese. Invasive cribriform carcinoma is usually low grade. In about 5-6% of invasive breast cancers, some portion of the tumor can be considered cribriform. Usually, some ductal carcinoma in situ of the cribriform type is present as well.
  

Signs and Symptoms - At first IDC may not cause any outward symptoms. Sometimes, the first sign is a lump or mass in the breast that you or your doctor can feel or an abnormal spot on a mammogram.

Invasive lobular carcinoma (ILC) is the second most common type of invasive breast cancer. It starts in the milk-producting lobules. According to the American Cancer Society, about 10% of all invasive breast cancers are ILC. This kind tends to occur later in life than invasive ductal carcinoma — the early 60s as opposed to the mid- to late 50s. Some research has suggested that the use of hormone replacement therapy during and after menopause can increase the risk of ILC.

Signs and Symptoms - At first ILC may not cause any symptoms. Sometimes, an abnormal area turns up on a routine mammogram but it tends to be more difficult to see on these tests. That’s because instead of forming a lump, the cancer cells spread out to the surrounding tissue in a line formation. Sometimes, the first sign of ILC is a thickening or hardening in the breast that can be felt, rather than a distinct lump. Other possible symptoms include an area of fullness or swelling, a change in the texture of the skin, or the nipple turning inward.

Signs and Symptoms of all breast cancers - Other symptoms besides those mentioned above include swelling of all or part of the breast, skin irritation or dimpling, breast pain, nipple pain or the nipple turning inward, redness, scaliness, or thickening of the nipple or breast skin, a nipple discharge other than breast milk, a lump in the underarm area.

Make sure to include the entire armpit area, between the breasts, and all the way up to the collarbone when doing self exams.