Definition and Overview
An infiltrating duct carcinoma of the breast, also known as an invasive ductal carcinoma, is a type of breast cancer that originates from the milk ducts and invades the fatty tissues of the breast. It is the most common type of breast cancer, accounting for up to 80% of all breast cancer cases.
As the term “invasive breast cancer” suggests, this type of cancer tends to spread to surrounding breast tissues. From its origin in the milk ducts, the cancer breaks through the ductal wall and invades the rest of the breast tissue. As a very aggressive form of cancer, it can also spread to other areas of the body and cause metastatic bone marrow cancer or cancer in the lymph nodes.
Causes of Condition
An infiltrating duct carcinoma of the breast can affect women of any age, but it tends to be more common among older women. The majority of women with DCIS are aged 55 and older. However, the condition can also affect men, although it is less common.
Breast cancer tends to affect women (and sometimes men) who meet certain risk factors:
Age – Up to 80% of breast cancer patients are women over the age of 50. Thus, women between 50 and 70 are advised to undergo regular breast cancer screening.
Genetics and family history – Patients who have a family history of breast or ovarian cancer face an increased risk of developing breast cancer as well. Thus, they are also advised to undergo regular screening. Those who are found to have genes that cause breast cancer, namely the BRCA1 and BRCA2, as well as some newly detected genes namely TP52 and CHEK2, can opt for preemptive treatment such as undergoing early surgery to remove breast tissue before cancer forms.
High levels of HER2 hormone receptor
Exposure to increased estrogen levels
Hormone replacement therapy
Being overweight or obese
Exposure to radiation
Use of contraceptives
Invasive ductal carcinoma does not immediately present with symptoms. Thus, many patients are diagnosed during a regular screening mammogram. This is why women are advised to undergo regular mammograms as they grow older, especially if they meet some of the risk factors mentioned above. Invasive breast cancer has special features that make it easier for doctors to detect them on a mammogram. They tend to have finger-like margins, which show that the cancer is already starting to spread to other tissues.
As the cancer continues to develop, it can begin to show some symptoms, such as:
Lump in the underarms
Nipple turning inward
Thickening of the nipple/breast skin
Upon the discovery of an abnormal lump through a mammogram or when the above symptoms are experienced, most patients undergo special testing to confirm whether the symptoms point to an infiltrating ductal carcinoma. These tests may include:
Ultrasound – An ultrasound scan may be performed to gather more information when mammogram results are deemed suspicious. An ultrasound can provide additional images of the breast cancer as the ultrasound energy bounces sound waves off it.
Breast MRI – A breast MRI or magnetic resonance imaging uses magnetic fields and radio waves that send information to a computer, which then produces clear images of the tissues.
Biopsy – A biopsy is a common part of breast cancer diagnosis. During the procedure, a small sample of the suspicious tissue is taken and examined under a microscope. There are now many types of biopsy used to diagnose ductal breast cancer. These include:
Core needle biopsy, wherein the doctor inserts a large needle to obtain cylindrical tissue samples from the suspicious area. In order to get the needle through the skin, the doctor has to make a small incision through the breast. This may leave a small scar.
Fine needle aspiration, wherein the doctor inserts a smaller hollow needle into the breast. Since the needle is very small, the patient will have no scars after the test.
Incisional biopsy, wherein the doctor performs a regular surgery to take out a small piece of the suspicious tissue. This usually becomes necessary when the results of the less invasive needle biopsies are inconclusive.
Excisional biopsy, wherein the doctor tries to remove all suspicious tissues.
CT scan – A computed tomography scan of other areas of the body may be performed to check whether the cancer has spread to other organs.
PET scan – This is a newer type of test wherein a radioactive material is injected into the patient’s body to obtain additional information during the scan. This is usually performed if the doctor suspects that the cancer has already spread to other organs.
Once diagnosed, the doctor will determine the stage of cancer, or how far it has spread from the milk ducts. Staging of invasive breast cancer depends on the size of the tumor, whether it has spread to the lymph nodes, and whether it has spread to other parts of the body. An infiltrating duct carcinoma of the breast can go from stage I to stage IV.
Other tests may also be performed to gather more information about the cancer, such as:
Grade – Infiltrating ductal carcinoma can be classified into three grades, namely grade 1 (low), grade 2 (moderate), and grade 3 (high). Grade 1 cells resemble healthy breast cells, while grade 2 and grade 3 cells show some abnormalities in both appearance and behavior. They also tend to grow faster and are more likely to spread to other body parts.
Surgical margin – It is important for doctors to determine the surgical margin, which encompasses the entire cancerous area as well as an extra margin of normal tissue immediately surrounding it. This information is very important when it comes to treating the cancer.
Hormone receptor assay – This test determines whether the cancerous cells have estrogen and progesterone receptors which can fuel their growth. If such receptors are indeed present, the patient may undergo hormonal therapy aside from cancer treatment in order to block the effects of said hormones.
HER2 receptor – Breast cancer cells that contain high levels of HER2 protein receptors tend to grow rapidly. Thus, these receptors need to be blocked so the cancer will grow more slowly. This treatment is called HER2-targeted therapy.
Who to See and Types of Treatment Available
A person diagnosed with infiltrating duct carcinoma of the breast needs special medical care from an oncologist and a multi-disciplinary team that includes a pathologist and other breast cancer specialists. Due to the prevalence of cancer, more and more cancer therapies are being developed. For breast cancer, available treatments include:
1.) Surgery - The goal of surgery is to remove the entire cancer tissue, which is why determining the surgical margin is important. Removing a margin of healthy tissue around cancerous tissue is important as even the smallest amount of cancerous tissue that remains in the breast may cause a recurrence. Surgery to remove cancerous breast tissue can be:
Lumpectomy, in which only the tumor and a surrounding margin of healthy tissue is removed
Total or simple mastectomy, in which the entire breast is removed
Modified radical mastectomy, in which the entire breast, as well as some chest wall muscle and lymph nodes under the arm, are removed
2.) Lymph node dissection – If the infiltrating ductal carcinoma has spread to the lymph nodes, the patient will also have to undergo this procedure in order to remove the affected nodes. There are two types of lymph node dissection, one of which removes only the sentinel node, or the lymph node that filters fluid away from the cancerous area. Another type is axillary dissection, in which an entire group of lymph nodes from under the arm is removed.
3.) Radiation therapy – Radiation therapy is currently one of the most advanced and commonly used cancer treatments. It works by directing high-energy radiation to cancerous cells in an attempt to destroy them. By destroying the cells’ DNA, this treatment significantly lowers the risk of recurrence. This is often performed after either a lumpectomy or a mastectomy to ensure that any remaining cancer tissues are destroyed.
4.) Chemotherapy – Chemotherapy destroys cancer cells using anti-cancer medicines, which can be taken orally or intravenously. However, this treatment has a high risk of side effects as it also destroys healthy tissue.
“Invasive ductal carcinoma.” BreastCancer.org. http://www.breastcancer.org/symptoms/types/idc
Pervez S, Khan H. “Infiltrating ductal carcinoma breast with central necrosis closely mimicking ductal carcinoma in situ (comedo type): a case series.” Journal of Medical Case Reports. 2007 1:83. https://jmedicalcasereports.biomedcentral.com/articles/10.1186/1752-1947-1-83
Barroso-Sousa R, Metzger-Filho O. “Differences between invasive lobular and invasive ductal carcinoma of the breast.” Therapeutic Advances in Medical Oncology. Sage Journals. http://journals.sagepub.com/doi/abs/10.1177/1758834016644156