Studies have proved breast cancer to be one of the leading cancers affecting females worldwide. The incidence is steadily rising, consequently increasing the morbidity and mortality rates. Increasing awareness and various screening measures have proved beneficial in detecting the disease in the initial stages. Early diagnosis of breast cancer results in a better prognosis, improved quality of life, and superior survival rates. Mammography is considered the gold standard for screening and diagnosing breast cancer.

However, due to a lack of specificity and easy accessibility, there is a need for a potentially viable alternative. Also, the pricey equipment, high maintenance, and specialized training make their usage challenging, especially in countries with constrained resources.

What Is Breast Ultrasonography?

Ultrasonography is a simple diagnostic procedure on par with mammography in diagnostic oncology. It uses sound waves to create images of the organs and tissues within the body. It is a safe, non-invasive, painless, and effective diagnostic procedure. Ultrasound can examine various organs such as lungs, breasts, uterus, ovaries, kidneys, liver, spleen, and prostate. Ultrasound examination of the breast is known as breast ultrasonography. Breast ultrasonography is most commonly indicated if any lump or mass is detected in the breast.

Why Is a Breast Ultrasound Done?

Breast ultrasound is indicated in the following conditions:

To characterize the breast lump as a benign or malignant tumor.
To differentiate cystic neoplasm from tumors.
In dense breasts where mammography may prove unsuccessful.
As a supplemental diagnostic aid to mammography.
To screen pregnant women as ultrasound is devoid of any radiation effects.
They are used as a screening tool in women with high-risk factors for breast cancer.
To aid in breast biopsy. This procedure is also known as ultrasound-guided biopsy, where the tissue sample is procured with the help of ultrasound.

How Is an Ultrasound Done?

Ultrasound uses high-frequency sound waves to create images of the structures within the body. These sound waves (inaudible to the human ear) are emitted into the body by a device known as a transducer. These sound waves bounce back upon striking some structures within the body. The transducer captures the returning sound waves, and a computer processes these sound waves into images. These images can be viewed in real-time on a screen.

What Are the Advantages of Ultrasound Over Mammography in Diagnosing Breast Cancer?

Breast ultrasound is a viable alternative to mammography for the initial diagnosis of breast cancer. The reasons are as mentioned below:

Cost-effective when compared to a mammogram.
Widely available and accessible.
Instrument portability makes ultrasound more preferable, especially in lower economic settings.
It can be used in dense breasts where mammography is contraindicated.
Ultrasound can be used to guide a biopsy procedure if required, thereby enhancing its efficacy in breast cancer.

What Is the Role of Ultrasound in Breast Cancer Screening?

Though mammography is the preferred screening tool for breast cancer, ultrasound has an equal sensitivity and specificity in initial diagnosis.
The positive predictive value of ultrasound is at par with mammography.
Considering the limitations of mammograms, ultrasound can be used as a potential screening tool for breast cancer.
With the increasing incidence of breast cancer and the lack of access to advanced imaging modalities, ultrasound can be an effective screening aid, especially in resource-constrained areas.
Studies have proved ultrasonography to have high cancer detection rates, particularly in diagnosing invasive cancers.
Effective screening tool for high-risk patients as they need to be screened periodically. The no-radiation protocol and cost-effectiveness of the ultrasound will help these patients undergo regular and safe screening procedures.

How Can Ultrasound Be Used to Diagnose Breast Cancer?

Ultrasound has proved valuable in diagnosing breast cancer. The efficacy, however, depends on the image quality obtained and their apt interpretation. This is achieved with the help of the BI-RADS (breast imaging reporting and data system) atlas. In addition, the BI-RADS system will help develop a standardized protocol for characterizing the lesion, reporting, and thereby the treatment. The BI-RADS classification is as follows:

How Can Ultrasound Distinguish Benign Tumors From Malignant?

Ultrasound can be used to distinguish cysts from tumors and also benign tumors from their malignant counterparts. The solid tumors can be classified as benign, intermediate, and malignant based on certain ultrasound features that are given below:

Benign Tumors:

To call a tumor benign, it should have no malignant features along with one of the three benign characteristics:

Strong, even hyperechogenicity(echogenicity is the number of sound waves reflected by the tissue). Hyperechogenic tissue reflects many sound waves. On the ultrasound, they appear light gray and are primarily composed of air, liquid, or fat but have no solid content.
Ellipsoid shape (wider-than-tall appearance) surrounded by a thin capsule (indicates a well-demarcated lesion).
Lobulated appearance with distinct boundaries.

Intermediate Tumors:

No malignant characteristics and none of the above three benign features.

Malignant Tumors:

To characterize a tumor as malignant, any one of the below-mentioned characteristics should be present on the ultrasound:

Irregular or spiked contour.
Taller-than-wide appearance.
Distinct hypoechogenicity (hypoechogenicity is when the reflected sound waves from the tissue are reduced. These are indicative of solid tumors or mass).
Sharp and angulated margins.
Calcifications within the lesion.
Branching pattern.
Increased vascularity within the lesion could be assessed with a Doppler ultrasound.

What Is an Ultrasound-Guided Biopsy?

It is essential to evaluate the abnormal tissue sample to obtain a confirmatory diagnosis. This procedure is known as a biopsy. An ultrasound-guided biopsy aids in locating the precise site to remove the tissue sample. It can also be used in fluid aspirations from the cyst, needle localization procedures, or surgical excision of small masses. In addition, ultrasound-guided biopsy has the advantage of reduced scarring and decreased organ distortion as the abnormal tissue site can be accurately determined with the help of an ultrasound.

What Are the Advances in Ultrasonography of Breast Cancer?

Novel advances are seen periodically in the field of diagnostic imaging. One such revolution is seen in ultrasound examination, that is, the sonoelastography procedure. Sonoelastography or ultrasound elastography is a diagnostic procedure that works on the principle of tissue elasticity. A pathology is diagnosed depending on the change in tissue elasticity from the standard range. Cancer tissues are more rigid than normal breast tissue, and hence they deform lesser than surrounding tissue when pressure is applied. This principle is applied to conventional ultrasound in diagnosing breast cancer. Therefore, sonoelastography is considered more accurate and reliable than conventional ultrasound in diagnosing cancer.

What Are the Benefits and Risks of Ultrasound?

Benefits:

Non-invasive and painless.
Cost-effective.
Easily accessible and well-tolerated by the patients.
Extremely safe as ultrasound does not use any radiation.
Real-time imaging is possible; hence can be used to guide procedures such as biopsy.
Ultrasound is the preferred imaging modality for soft tissues as it is not evident in other imaging techniques.
The preferred technique to categorize any breast lesion.

Risks:

No known risks to humans.
The rare possibility of false-positive results leads to additional diagnostic testing.

Conclusion:

With the incidence of breast cancer increasing globally, the need of the hour is a quick, easily accessible, and cost-effective diagnostic tool that can be used comprehensively. Ultrasound is an economical, portable, widely available, and reliable tool with high sensitivity and specificity in diagnosing breast cancer. In addition, using ultrasound as an initial detection tool, especially in resource-constrained areas, can provide timely management and decrease mortality rates.