Introduction: Who Should Undergo Diagnostics

Most people with breast cancer in situ do not experience noticeable symptoms. The condition is typically found during routine screening rather than because someone feels unwell or notices changes. This is one reason why regular mammograms are so important for early detection.^[1]

Women who participate in breast cancer screening programs are the group most likely to have breast cancer in situ diagnosed. Since the introduction of routine mammography screening, the number of people diagnosed with this condition has increased significantly. Before widespread mammography screening became common, fewer than 5 percent of newly diagnosed breast cancers were breast cancer in situ. Today, this early form represents about 20 to 25 percent of all breast cancer diagnoses in the United States.^[8]

Around 7,300 women are diagnosed with breast cancer in situ in the United Kingdom each year, while an estimated 59,080 new cases are expected to be diagnosed in women in the United States annually. Men can also develop this condition, though it is extremely rare, accounting for less than 0.1 percent of all cancer diagnoses in men.^[2][5]

You should seek medical evaluation if you notice any changes in your breast, even if they seem minor. While breast cancer in situ usually doesn’t cause symptoms, some people may experience a breast lump, discharge from the nipple that might contain blood, or a rash on the nipple that appears red and scaly. Any of these signs warrant a visit to your doctor for proper assessment.^[1][2]

Certain factors may increase your risk of developing breast cancer in situ, which means you might benefit from being particularly vigilant about screenings. These risk factors include having a biological family history of breast cancer, having previously had breast cancer or unusual cell growth in the breast called atypical hyperplasia, being over age 30, starting your period before age 12, having your first baby after age 30, or having dense breast tissue. Women who carry gene mutations known as BRCA1 or BRCA2, have had previous radiation therapy to the chest area, have never been pregnant or breastfed, or started menopause after age 55 also face higher risk.^[5]

However, it’s important to understand that having one or more risk factors doesn’t mean you will definitely develop breast cancer in situ. Risk factors simply indicate a higher probability compared to people without those factors. Most people diagnosed with breast cancer in situ don’t have family members with breast cancer, which shows that anyone can develop this condition regardless of family history.^[5]

Diagnostic Methods

Mammography Screening

The vast majority of breast cancer in situ cases, more than 90 percent, are discovered during routine mammogram screenings. A mammogram is an X-ray examination of the breast tissue that can detect abnormalities before they can be felt or cause symptoms. During a mammogram, your breast is positioned on a special platform and gently compressed while X-ray images are taken from different angles. This compression might feel uncomfortable for a moment, but it’s necessary to get clear images of the breast tissue.^[5]

On a mammogram, breast cancer in situ typically appears as tiny white specks scattered in the breast tissue. These white specks are calcium deposits, often called calcifications. These calcifications form when calcium builds up in the breast ducts where abnormal cells are present. Not all calcifications mean cancer, but certain patterns of calcifications can suggest the presence of breast cancer in situ and require further investigation.^[1]

If your screening mammogram shows something concerning, your doctor will order additional tests. A diagnostic mammogram is usually the next step. This is similar to a screening mammogram but takes more detailed views at higher magnification from more angles than a regular screening mammogram. This allows doctors to get a closer look at the suspicious area and better understand what they’re seeing.^[10]

Ultrasound Examination

Your doctor may also recommend a breast ultrasound to further evaluate concerning findings from your mammogram. An ultrasound uses sound waves to create images of the inside of your breast. During this test, a technician applies a gel to your breast and moves a small device called a transducer over the area. The sound waves bounce off the breast tissue and create pictures on a screen.^[10]

Ultrasound is particularly useful for examining areas of concern in women with dense breast tissue, where mammogram images might be harder to interpret. It can also help doctors determine whether a suspicious area is solid or fluid-filled, which provides important information about the nature of the abnormality.

Magnetic Resonance Imaging (MRI)

In some cases, your doctor might order a breast MRI scan. This test uses powerful magnets and radio waves to create detailed images of your breast tissue. An MRI can sometimes detect areas of concern that don’t show up clearly on mammograms or ultrasounds. This test is particularly valuable for women with dense breasts or those at high risk for breast cancer.^[10]

During a breast MRI, you lie face down on a padded table with your breasts positioned in openings. The table slides into a tube-shaped machine that takes images while you remain still. The test typically takes about 30 to 60 minutes. You may receive an injection of a contrast dye before or during the scan to make certain areas show up more clearly in the images.

Breast Biopsy

While imaging tests can suggest the presence of breast cancer in situ, a biopsy is always needed to confirm the diagnosis. A biopsy involves removing a small sample of breast tissue so it can be examined under a microscope by a doctor who specializes in analyzing body tissues, called a pathologist.^[10]

There are several types of biopsies that might be used. A core needle biopsy is one of the most common methods. During this procedure, your doctor uses a hollow needle to remove small cylinders of tissue from the suspicious area. The procedure is usually done with local anesthesia to numb the area, so you shouldn’t feel significant pain. Your doctor will use mammogram or ultrasound images to guide the needle to exactly the right spot.^[10]

Another type is a stereotactic biopsy, which uses special mammogram equipment to pinpoint the exact location of the suspicious area in three dimensions. During this procedure, your breast is compressed, similar to during a regular mammogram, while images are taken from different angles to map the location of the abnormality. Once the location is confirmed, a needle is inserted to remove tissue samples.^[10]

Less commonly, doctors might perform an excisional biopsy, which involves making a small cut in the breast and removing the entire suspicious area along with some surrounding tissue. This type of biopsy is sometimes used when needle biopsies don’t provide enough information or when the suspicious area is difficult to reach with a needle.

Grading the Abnormal Cells

After tissue samples are collected through biopsy, a pathologist examines them under a microscope. One important aspect of this examination is determining the grade of the abnormal cells. Grade refers to how abnormal the cells look compared to normal, healthy cells. This information helps doctors understand how quickly the abnormal cells might be growing.^[2]

Breast cancer in situ is divided into three grades: low grade, intermediate grade, and high grade. Low grade means the cells look more similar to normal cells and tend to grow more slowly. High grade means the cells look very different from normal cells and may grow more quickly. Doctors believe that high grade breast cancer in situ is more likely to come back after treatment or to develop into invasive cancer that spreads into the surrounding breast tissue.^[2]

Staging the Disease

Staging is a way doctors describe how far cancer has spread in the body. Breast cancer in situ is always considered the earliest possible stage because the abnormal cells are confined within the milk ducts and have not started spreading into surrounding tissue.^[2]

In the number staging system, which divides cancers into stages 0 through 4, breast cancer in situ is classified as stage 0. In the TNM staging system, which is another commonly used method, it is classified as Tis N0 M0. This means the tumor is still in its original place (Tis stands for tumor in situ), no lymph nodes are involved (N0), and the cancer has not spread to other parts of the body (M0).^[2]

Diagnostics for Clinical Trial Qualification

Clinical trials are research studies that test new approaches to diagnosing, treating, or managing medical conditions. If you’re interested in participating in a clinical trial for breast cancer in situ, you’ll need to undergo specific tests and evaluations to determine if you qualify for the study.

The diagnostic criteria for enrolling in clinical trials are typically very specific. Most trials require confirmation of breast cancer in situ through a biopsy that has been reviewed by a pathologist. The biopsy results will need to clearly show that abnormal cells are present in the milk ducts but have not invaded the surrounding breast tissue.

Many clinical trials also require specific information about the grade of your breast cancer in situ. Some studies might only accept patients with high grade disease, while others might include all grades. Your healthcare team will review the pathology report from your biopsy to determine which trials you might be eligible for.

You may need additional imaging studies as part of the screening process for a clinical trial. This could include mammograms, ultrasounds, or MRI scans to document the size and location of the area affected by breast cancer in situ. These baseline images help researchers track changes over time and measure how well the treatment being studied works.

Blood tests are often required before enrolling in clinical trials. These tests check your overall health and organ function to make sure it’s safe for you to participate in the study. Blood tests typically examine your kidney function, liver function, blood cell counts, and sometimes hormone levels or specific proteins in your blood.

Some clinical trials may require testing for specific biomarkers or genetic characteristics of your cancer cells. For example, researchers might want to know if the cancer cells have receptors for hormones like estrogen or progesterone. This information can be obtained from your biopsy sample and helps determine if a particular treatment being studied would be appropriate for your specific type of breast cancer in situ.

You’ll also need to provide a complete medical history and undergo a physical examination. The research team will want to know about any other health conditions you have, medications you’re taking, previous treatments you’ve received, and whether you’ve had cancer before. This information helps ensure that participating in the trial won’t put your health at risk and that the results won’t be affected by other factors.

Each clinical trial has its own specific eligibility criteria, so the exact tests you need will depend on which study you’re considering. Your doctor can help you understand what diagnostic tests would be required for any trials that might be appropriate for your situation.