Exploring the Different Types of Breast Cancer

Breast cancer can come in many forms, but the anxiety and devastation that may come with any breast cancer diagnosis are valid emotions that you may feel. It can be overwhelming to navigate the various forms of breast cancer. However, gaining an understanding of the different types can help you prepare for what lies ahead.

DCIS is a non-invasive cancer or a pre-invasive form of breast cancer where the normal cells in a breast’s milk ducts have changed into cancer cells and multiplied. However, these cells have not penetrated through the ductal basement membrane (outermost wall of breast ducts) and spread to the surrounding breast tissue. DCIS is a very early form of cancer that is highly treatable, but may become invasive if left untreated or undetected.

DCIS is classified as a stage 0 cancer as the atypical cells have not spread outside of the ducts.

Invasive ductal carcinoma (IDC)

IDC refers to breast cancer that originates from the cells that line the milk duct in the breast, but have grown past the lining wall and spread to the surrounding breast tissue. It is the most common type of invasive breast cancer. Approximately 80% of all invasive breast cancers are IDCs.

Invasive lobular carcinoma (ILC)

ILC refers to breast cancer that starts in the lobules in the breast, but has progressed and spread to the surrounding tissue. ILC is the second most common type of invasive breast cancer. Around 10% of all invasive breast cancers are ILCs.

IDCs and ILCs that are left untreated or uncontained may metastasize and spread to other parts of the body through the lymphatic system or the bloodstream as they continue to multiply and grow.

Inflammatory breast cancer (IBC)

Inflammatory breast cancer is a rare form of breast cancer where the cancer cells block the lymph channels in the breast, causing the breast to look red and “inflamed”, thus the name inflammatory breast cancer. Approximately 1% to 5% of all breast cancers diagnosed in the United States are IBC and most IBCs are invasive ductal carcinomas. IBC is an aggressive cancer that progresses rapidly, within weeks or months, which makes it difficult to detect before metastasis. In approximately 30% of IBC cases, it has already metastasized to distant parts of the body. As compared to other breast cancer types, IBC has the following characteristics:

• Tend to be diagnosed at a younger age
• More common in African American women
• More common in obese women
• Tend to be hormone receptor negative (these cancers cannot be treated with hormone therapy)

Learn more: Invasive Breast Cancers: What You Need to Know

Triple-negative breast cancer refers to breast cancer that tests negative for estrogen or progesterone receptors and makes little to none of the human epidermal growth factor receptor 2 (HER2) protein. Most breast cancer cells have receptors for the hormones estrogen or progesterone, which helps them to grow and are known to be hormone receptor-positive, estrogen receptor-positive or progesterone receptor-positive. These cancers can usually be treated with hormone therapy that prevents these hormones from binding to the cancer cells and thus slowing down or preventing their growth. Other cancer cells have high levels of the HER2 protein on their surfaces, which promotes growth. This type of cancer is called HER2-positive breast cancer and can normally be treated with drugs that target HER2. As TNBC tests negative for both these hormones and HER2, the respective treatments do not work for TNBC. However, there are other methods to treat TNBC.

Paget disease of the breast is a rare type of breast cancer involving the skin of the nipple and the areola (dark circle around the nipple). Only about 1% to 4% of all breast cancer cases involve Paget disease. In 80 to 90% of Paget disease cases, a tumor or multiple tumors can be found within the breast. The tumors found are usually either ductal carcinoma in situ (DCIS) or invasive breast cancer. Paget disease of the breast can occur in both males and females but is predominant in post-menopausal females (due to the predominance of breast cancer in females in general).

An angiosarcoma is a very rare but fast and aggressive form of cancer that begins in the cells in the inner lining of blood vessels or lymph vessels. Approximately 0.1% to 0.2% of all breast cancers are angiosarcomas. Angiosarcomas of the breast can generally be grouped into primary and secondary angiosarcomas. Primary sarcomas occur in people who have never been treated for breast cancer, while secondary angiosarcomas occur in people who have previously been treated for breast cancer, especially for those who have gone through radiation therapy. Secondary angiosarcomas occur typically 6 to 10 years after radiation therapy.

Phyllodes tumors are rare breast tumors that grow in the connective tissue of the breast. Most (around 75%) are benign, but they can sometimes turn malignant. Less than 1% of all breast tumors are phyllodes tumors. As it is challenging to differentiate between phyllodes tumors and fibroadenomas, especially in imaging and on core biopsy specimens, they may sometimes be misdiagnosed. Phyllodes tumors can be found at any age, but women in their 40s may have an increased risk. Women with Li-Fraumeni syndrome have also been found to have an increased risk of developing phyllodes tumors.

It is important to get a proper diagnosis as different breast cancer types will require different treatment plans. If you have not gotten a diagnosis but are worried that you may have breast cancer due to certain signs or symptoms, do not be afraid and visit a doctor soon to get it checked. Most breast conditions are non-cancerous, but it is better to be sure. Breast cancer that is detected early has a much higher chance of being cured with the least extensive treatments.