Also referred to as infiltrating ductal carcinoma or invasive ductal breast cancer, invasive ductal carcinoma (IDC) is a type of invasive breast cancer wherein the cancer cells have moved outside the milk ducts and affected surrounding tissues. In other words, the cancer has attacked the lymph nodes and is on its way to hurt other body parts if not curtailed. Milk ducts are tubes carrying milk to the nipple from the lobules. The word ‘invasive’ indicates the cancer has infiltrated nearby breast tissues. ‘Ductal’ denotes the cancer stemmed in the milk ducts. ‘Carcinoma’ means a cancer that has begun its journey in cells constituting the skin or tissue that lines the kidneys, liver or other organs.
IDC represents 80 percent of all diagnosed invasive breast cancers, making it the most common type. The cancer cells spread by directly invading the overlying skin and fat tissues. The cells then attack the lymph nodes within the axilla. From here, it becomes easier for the cells to reach the lymph nodes of the supraclavicular region (near the collar bone) and neck and then into the blood vessels. Upon entering the blood vessels, the cancer cells spreads to distant organs like lung or liver, or bones.
There are different stages and types of IDC. The following are the five major types:
- Medullary carcinoma of the breast: The cancer cells look highly aggressive and abnormal but they do not act like one.
- Tubular carcinoma of the breast: A less aggressive form of breast cancer that responds to treatment well.
- Mucinous carcinoma of the breast: A rare invasive ductal carcinoma type that’s aggressive and can spread to nearby healthy tissue beyond the milk duct.
- Papillary carcinoma of the breast or papillary breast cancer: A rare invasive breast cancer type that doesn’t account for more than a percent of all diagnosed breast cancer cases.
- Cribriform carcinoma of the breast: The cancer cells invade the breast’s connective tissues between the lobules and milk ducts.
Like most other types of breast cancer, invasive ductal carcinoma also doesn’t cause any apparent symptoms. Usually, the affected woman realizes she has the condition only during routine mammography. In certain cases, the first apparent sign is a fresh mass or lump in the breast felt through physical examination. Other symptoms include skin dimpling or irritation, partial or complete breast swelling, breast and/or nipple pain, thickening or redness of the breast or nipple skin, a lump under the arm, and nipple discharging fluid other than milk.
Target Group & Risk Factors
This cancer type can affect women of any age, race, ethnicity, etc. However, older women (55 years of age or more) are the likeliest victims. Though rare, the disease could also affect men. Some of the cancer’s risk factors include personal or familial breast cancer history, obesity, alcohol consumption, having first child after 35 years of age, not breastfeeding the kid, and physical inactivity.
The diagnosis entails a blend of several testing procedures such as imaging tests and a physical breast exam. During the physical test, the lymph nodes above the collarbone and under the armpit would be examined to determine if there are any unusual changes such as swelling. The imaging tests would comprise a mammography, ultrasound, breast MRI, and/or biopsy. In a biopsy, a sample of the abnormal-appearing tissue would be harvested for further testing under a microscope. There are different types of biopsies such as incisional biopsy, excisional biopsy, core needle biopsy, and fine needle aspiration that a doctor may resort to based on how conclusive the results are with the other biopsies and tests.
The treatment for IDC is typically categorized as local and systemic. Local treatment methods are radiation therapy and surgery. Systemic treatment encompasses hormonal therapy, chemotherapy, and/or targeted therapy. Treatment typically begins with surgery, where the objective is to eliminate the cancer with a mastectomy or lumpectomy. But if the tumor is big or there’s a wider spread, hormonal therapy or chemotherapy could be first administered to reduce the cancer.
The kind of surgery chosen would depend on multiple factors such as tumor location, cancer size, and whether multiple areas within the breast have been affected. Additional surgery may be required to make sure there are zero traces of the cancer left behind. This means some healthy tissues bordering the affecting tissue could also be removed. The healthy tissue removed could be less or more than 2mm, depending on the hospital or surgeon.