Invasive ductal carcinoma is the most common type of invasive breast cancer. It starts in the milk ducts of the breast and then grows into the nearby breast tissue.
This type of cancer may cause a breast lump, changes in breast shape, nipple changes, skin dimpling or nipple discharge. However, some cases are found during a routine mammogram before symptoms appear.
Treatment depends on the size and stage of the tumor, whether cancer has reached the lymph nodes, and the cancer’s hormone receptor and HER2 status. Options may include surgery, radiation therapy, chemotherapy, hormone therapy or targeted therapy.
Main symptoms
Invasive ductal carcinoma may not cause symptoms in the early stages, but possible signs can include:
-
A new lump or thick area in the breast or underarm
-
Breast swelling or a change in breast size or shape
-
Skin dimpling, redness, thickening or irritation
-
Nipple turning inward
-
Nipple discharge, especially if bloody
-
Breast or nipple pain
-
A sore or rash on the nipple or breast skin
-
Swollen lymph nodes near the armpit or collarbone
When cancer spreads to other parts of the body, it may also cause symptoms such as bone pain, shortness of breath, cough, belly swelling, weight loss or headaches, depending on where it has spread.
Any new breast lump, nipple discharge, skin change or change in breast shape should be assessed by a doctor, even if there is no pain.
Possible causes
Invasive ductal carcinoma develops when abnormal cells in a breast duct grow out of control and invade nearby breast tissue.
Several factors can increase the risk of this type of breast cancer, although having risk factors does not mean cancer will definitely develop.
1. Genetic changes and family history
Inherited gene changes, such as BRCA1 and BRCA2 mutations, can increase the risk of breast cancer. A family history of breast cancer can also raise risk, especially when close relatives were diagnosed at a younger age.
These genes normally help repair damaged DNA. When they do not work well, abnormal breast cells may be more likely to survive and multiply.
2. Hormonal and reproductive factors
Hormones can affect the growth of some breast cancers. Risk may be higher in people exposed to estrogen for a longer time, such as those who started periods early or entered menopause later.
Other reproductive factors, such as never having a full-term pregnancy or having a first pregnancy later in life, may also affect breast cancer risk.
3. Age and breast tissue changes
The risk of invasive ductal carcinoma increases with age. Over time, cells can collect genetic changes that may make abnormal growth more likely.
Some breast cancers may also develop from ductal carcinoma in situ, or DCIS. DCIS means abnormal cells are still inside the milk duct, while invasive ductal carcinoma means the cancer has grown through the duct wall into nearby tissue.
4. Lifestyle and environmental factors
Some lifestyle factors are linked to a higher risk of breast cancer. These can include alcohol use, obesity after menopause, low physical activity and smoking.
Past radiation therapy to the chest, especially at a young age, can also increase risk. These factors do not directly cause every case, but they may make breast cancer more likely in some people.
Confirming a diagnosis
Diagnosis usually starts with a breast exam and imaging tests. A mammogram is commonly used, and a breast ultrasound or MRI may be recommended if more detail is needed.
A biopsy is needed to confirm invasive ductal carcinoma. During a biopsy, a small sample of breast tissue is removed and checked under a microscope to see if cancer cells are present and whether they have invaded nearby tissue.
Pathology testing also helps guide treatment. Doctors look at the tumor size, grade, lymph node involvement, stage, estrogen receptor status, progesterone receptor status and HER2 status.
Treatment options
Treatment for invasive ductal carcinoma depends on the stage of the cancer, tumor features, overall health and whether the cancer cells have hormone receptors or HER2 changes. Many people need more than one type of treatment.
1. Surgery
Surgery is often one of the main treatments. A lumpectomy removes the tumor and a small area of healthy tissue around it, while a mastectomy removes the whole breast.
Doctors may also check nearby lymph nodes to see if cancer has spread. This can help guide the need for additional treatment after surgery.
2. Radiation therapy
Radiation therapy uses high-energy rays to destroy cancer cells. It is often recommended after lumpectomy to lower the risk of the cancer coming back in the breast.
It may also be used after mastectomy in some cases, especially if the tumor is large or cancer has spread to lymph nodes.
3. Chemotherapy
Chemotherapy uses medicines that kill fast-growing cells. It may be given before surgery to shrink a tumor or after surgery to reduce the risk of cancer returning.
The need for chemotherapy depends on factors such as tumor size, grade, lymph node involvement, receptor status and recurrence risk.
4. Hormone therapy
Hormone therapy may be used when cancer cells have estrogen or progesterone receptors. These medicines lower hormone effects or block hormones from helping cancer cells grow.
This treatment is often taken for several years after surgery. It can help lower the risk of the cancer coming back.
5. HER2-targeted therapy
Some invasive ductal carcinomas have too much HER2, a protein that can make cancer grow faster. HER2-targeted therapy can block this signal and help control the cancer.
These medicines are usually used together with other treatments, such as chemotherapy, depending on the stage and treatment plan.
6. Other targeted or advanced treatments
Some people may need other targeted medicines, especially if the cancer is advanced or has specific tumor features. Treatment can also include medicines that help control cancer spread, reduce symptoms and improve quality of life.
Treatment is usually planned by a cancer care team, which may include a breast surgeon, medical oncologist, radiation oncologist and other specialists.