Invasive Ductal Carcinoma (IDC) is the most common form of invasive breast cancer, which means it has spread into the surrounding breast tissues. IDC accounts for around 80% of all invasive breast cancers. According to the American Cancer Society, more than 180,000 women in the United States are diagnosed with invasive breast cancer each year.
IDC can be detected as breast cancer during a physical exam or imaging tests such as a mammogram. If cancerous cells have spread beyond the milk duct, the diagnosis advances to invasive ductal carcinoma. Inherited genetic mutations in the BRCA1 and BRCA2 genes have been studied and proven as risk factors of some invasive breast cancers.
What is Invasive Ductal Carcinoma?
IDC develops in the lining of the milk ducts, that are responsible for carrying milk to the nipple from the lobules of the breast. The cancer can spread to other parts of the body through the blood or lymphatic systems. Over time, invasive ductal carcinoma can spread to the lymph nodes and possibly to other areas of the body.
There are three grades assigned to IDC that range from 1 to 3. The grades are determined by how the cancer appears under a microscope. The grade gives an insight to how the cells will behave and what treatments have the best chance to be effective.
- Grade 1: Known as well differentiated, the cells look and behave almost as normal breast cells. These cells are less likely to spread than higher grades and are usually slow growing.
- Grade 2: Known as the moderate grade, the cells look a bit more abnormal and divide a little faster. The cells grow faster than in grade 1 IDC but are less likely to spread than grade 3.
- Grade 3: Also called poorly differentiated, the cells do not behave like healthy breast cells. They are more likely to spread and divide much quicker than normal cells.
What are the Treatment Options for Invasive Ductal Carcinoma?
Most women with invasive breast cancer first undergo surgery to remove the tumor. Surgical treatment for invasive breast cancer follows the same approach, whether the patient has an invasive lobular or invasive ductal cancer. If currently inoperable, chemotherapy may be given prior to surgery to shrink tumors and destroy rapidly dividing cancer cells, or after the surgery to address any residual cancer cells and reduce the likelihood of recurrence.
The most common treatments for IDC include:
- Sentinel lymph node biopsy
- Axillary lymph node dissection
- Radiation therapy
- Hormonal therapy