There are two types:
- Ductal carcinoma in situ (DCIS), also called intraductal carcinoma
- Invasive ductal carcinoma (IDC)
The symptoms, diagnosis, and treatment for each are different.
Ductal Carcinoma in Situ
DCIS accounts for 1 of every 5 new breast cancer diagnoses. It's an uncontrolled growth of cells within the breast ducts. It’s noninvasive, meaning it hasn’t grown into the breast tissue outside of the ducts. The phrase "in situ" means "in its original place."
DCIS is the earliest stage at which breast cancer can be diagnosed. It's known as stage 0 breast cancer. The vast majority of women diagnosed with it are cured.
Even though it’s noninvasive, it can lead to invasive cancer. It's important that women with the disease receive medical treatment. Experts believe that up to 30% of women with DCIS will develop an invasive breast cancer within 10 years of the DCIS diagnosis. The invasive cancer usually develops in the same breast and in the same area as where the DCIS happened.
How is ductal carcinoma in situ diagnosed?
This type of cancer doesn’t usually cause a lump in the breast that can be felt. Symptoms of DCIS include breast pain and a bloody discharge from the nipple. About 80% of cases are found by mammograms. On the mammogram, it appears as a shadowy area.
If your mammogram suggests that you may have DCIS, your doctor should order a biopsy to analyze the cells and confirm the diagnosis. Biopsies for DCIS are typically done using needles to remove tissue samples from the breast.
If you have DCIS, your doctor may order more tests to gather information about your cancer. These tests may include an ultrasound or MRI. Based on the results of various tests, your doctor will be able to tell the size of your tumor and how much of your breast is affected by the cancer.
How is ductal carcinoma in situ treated?
No two patients are the same. Your doctor will customize your treatment plan based on your test results and medical history. Among other things, your doctor will consider:
- Tumor location
- Tumor size
- Aggressiveness of the cancer cells
- Your family history of breast cancer
- Results of tests for a gene mutation that would increase the risk of breast cancer
Most women with DCIS don't have the breast removed with a mastectomy. Instead, they have breast-conserving surgery.
Most common is a lumpectomy followed by radiation. In a lumpectomy, the surgeon removes the cancer and a small area of healthy tissue around it. The tissue is taken to make sure all the cancer cells have been removed. Lymph nodes under the arm don’t need to be removed as they are with other types of breast cancer.
After lumpectomy, radiation significantly reduces the likelihood that the cancer will come back. If cancer does return, it’s called recurrence. Radiation can be given to the entire breast, or it can be taken internally to target certain areas of the breast.
Some women with an extremely low likelihood of cancer recurrence may have a lumpectomy only. This may be an option for older women with small tumors whose surgery showed large amounts of healthy tissue on all sides of the cancer. Discuss the risks of not having radiation with your doctor before deciding against it.
You and your doctors may decide that a mastectomy to remove the breast is the best course of treatment if you have any of the following:
- A strong family history of breast cancer
- A gene mutation that increases the risk of breast cancer
- Very large areas of DCIS
- DCIS lesions located in multiple areas throughout your breast
- Inability to tolerate radiation therapy
You and your treatment team may also consider the use of hormone therapy. It may reduce the risk of invasive breast cancer not only in the breast with cancer, but in the opposite breast as well. This risk reduction continues even after you stop taking the medication.
Invasive Ductal Carcinoma
IDC accounts for about 80% of all invasive breast cancers in women and 90% in men.
Like DCIS, it begins in the milk ducts. But unlike DCIS, invasive ductal carcinoma is not contained. Instead, it grows through the duct walls and into the surrounding breast tissue. And it can spread to other parts of your body.
How is invasive ductal carcinoma diagnosed?
IDC may cause a hard, immovable lump with irregular edges to form in your breast. It can sometimes be felt during a breast examination. In some cases, the cancer causes the nipple to become inverted. A mammogram may show areas of calcification -- where calcium has collected.
If your physical exam and mammogram indicate you may have IDC, you’ll have a biopsy to collect cells for analysis. Your doctor can make a diagnosis from the biopsy results.
Since IDC often spreads, you’ll likely have additional tests to look for cancer cells in other areas of your body. These tests may include:
- CT scan. It's a powerful X-ray that makes detailed pictures inside your body.
- PET scan . Used together with a CT scan, this test can help find cancer in lymph nodes and other areas.
- MRI. It uses strong magnets and radio waves to make pictures of the breast and other structures inside your body.
- Bone scan. A radioactive substance called a tracer is injected your arm, and pictures are taken to find out if cancer may have traveled to your bones.
- Chest X-ray: It uses radiation in low doses to make images of structures inside your chest.
Your doctor will also take samples from your lymph nodes in the armpits to check for cancer. This is called axillary lymph node dissection.
The results from these tests will determine the stage of your cancer, and knowing the stage will help guide your treatment.
How is invasive ductal carcinoma treated?
Most women with IDC have surgery to remove the cancer. The choice between a lumpectomy or mastectomy will depend on the size of your tumor and how much it has spread throughout your breast and surrounding lymph nodes.
In addition to surgery, most doctors will recommend other treatments including chemotherapy, hormone therapy, radiation therapy, or a combination of these treatments.
Chemotherapy and hormone therapy target cancer cells throughout your entire body. Radiation specifically focuses on the area around your breast cancer. The use of radiation will depend on the type of surgery you have (lumpectomy or mastectomy), the size of the tumor, whether it has spread, and the number of lymph nodes with cancer cells.