Invasive breast cancer

Invasive breast cancer is the most common type of breast cancer, occurring when cancer cells form in the ducts or glands (lobules) and spread into the surrounding breast tissue. Invasive or infiltrating breast cancer, sometimes referred to as invasive mammary carcinoma, accounts for 80 percent of all breast cancer diagnoses, according to the American Cancer Society.

There are many effective treatment options for each kind of invasive breast cancer.

Common types of invasive breast cancer

There are several subgroups of invasive breast cancer, each slightly different than the other. The three most common are:

Invasive (infiltrating) ductal carcinoma: Also known as IDC, this cancer type originates in the lining of milk duct cells before spreading into the breast tissue. It’s the most common of all breast cancer types.

Invasive lobular carcinoma: Invasive lobular carcinoma, or ILC, begins in the breast lobules, or glands that make milk. ILC is less common than IDC.

Inflammatory breast cancer: This is a very rare type of invasive breast cancer caused by a tumor or tumors blocking the skin’s lymph vessels. It may cause symptoms, like swelling and red skin, that make the breasts feel inflamed.

Both IDC and ILC may spread past the breast tissue to other parts of the body, such as the lymph nodes. Early detection is key with invasive breast cancers, since the disease has better outcomes when the cancer is still localized to the breast tissue.

Less common kinds of invasive breast cancer

Other subgroups of invasive breast cancer are less common. These include:

• Medullary carcinoma
• Adenoid cystic carcinoma, also referred to as adenocystic carcinoma
• Papillary carcinoma
• Mucinous carcinoma, also referred to as colloid carcinoma
• Tubular carcinoma
• Low-grade adenosquamous carcinoma

Overall, these cancers are considered to have better outcomes than invasive ductal carcinoma.

However, other types of invasive breast cancer tend to be more challenging to treat than invasive ductal carcinoma, including:

• Micropapillary carcinoma
• Mixed carcinoma
• Most kinds of metaplastic carcinoma (including spindle cell and squamous, excluding low-grade adenosquamous carcinoma)

Symptoms

While not everyone experiences symptoms when diagnosed with invasive breast cancer, it’s important to be aware of potential symptoms. Invasive breast cancer symptoms may include:

• Changes to the skin on and around the breast, including redness, dimpling, puckering or unexplained rash
• Fluid discharge from the nipple
• A lump in or around the breast or armpit
• A change in the shape or feel of the breast

Noninvasive breast cancer may also cause fluid discharge or lumps as well, so some of the symptoms are the same for both types of cancer. Seeking medical advice about any unexpected changes to the breasts is key to identifying issues as early as possible.

Causes and risk factors

Like many cancer types, invasive breast cancer has several risk factors. However, having one or more of the risk factors doesn’t mean cancer is inevitable, only that the risk is higher.

Invasive breast cancer risk factors include:

• Certain genetic mutations, such as BRCA1 and BRCA 2 
• Age
• A family history of the disease or of ovarian cancer 
• Dense breast tissue
• A previous diagnosis of breast cancer or other breast diseases such as lobular carcinoma in situ or atypical hyperplasia 
• Alcohol consumption
• Sedentary lifestyle
• Excess weight, especially after menopause
• Certain history with childbearing (not having given birth or having a first child after the age of 30 raises the risk)
• Use of hormone therapy

Some of these risk factors are also the same as those for noninvasive breast cancer, including:

• No previous childbearing history
• Childbirth later in life
• Family history
• Genetic changes

While some risk factors can’t be changed, others may be modified with changes to diet and lifestyle habits.

Treatment options

The recommended treatment plan depends on several factors, including:

• Overall health
• The type, grade and size of the cancer
• Whether the cancer has spread to other parts of the body
• Whether the cancer is receptive to hormone therapy 

Sometimes, multiple treatment options will be used in combination. An expert cancer care team can advise patients on the appropriate treatment options for their specific type of invasive breast cancer. The most common treatment options include:

Surgery: A variety of surgical procedures may be used to remove cancer cells and cancerous tissue. Two common surgical approaches include lumpectomy and mastectomy.

• During a lumpectomy, the breast tumor and some of the surrounding tissue is removed by a surgeon.
• If the tumor is larger, the entire breast may be removed in a procedure called a mastectomy. Sometimes, nearby lymph nodes are also removed. Mastectomy may be performed at the same time, or in a different procedure, as breast reconstruction.

Radiation therapy: During radiation treatment, high-energy X-rays are used to specifically target and kill cancer cells. External beam radiation, which uses a machine outside the body to deliver targeted doses of radiation, is most commonly used for invasive breast cancer.

Chemotherapy: Chemotherapy uses medication to kill cancer cells or stop them from growing. These anti-cancer medications are generally given in cycles over the course of several weeks.

Hormone therapy: Also called endocrine therapy, this treatment is designed to stop the growth of cancer cells. It’s only used on tumor types that are dependent on hormones, such as estrogen, to grow. It may be used before surgery to shrink the tumor or after surgery to prevent the cancer from recurring.

Targeted therapy: This treatment is designed to target specific genes or proteins that help drive the cancer’s behavior, while—unlike systemic chemotherapy—avoiding damage to healthy cells.

Immunotherapy: For some types of breast cancer, immunotherapy may be recommended. This treatment is designed to empower the body’s immune system to recognize cancer cells as harmful and unleash an immune response to kill them.