October is Breast Cancer Awareness Month, a good time to review and share the screening options for breast cancer.
In the U.S., around one in eight women will develop breast cancer during their lifetime, while for men that figure is one in 883. The incidence rates of breast cancer in the U.S. actually began to decrease after the year 2000, following two decades of increasing rates.
While almost 42,000 women die annually as a result of breast cancer, the death rate has been decreasing since 1989. This is largely attributed to treatment advances, improved awareness and of course, early detection via screening.
Here is some vital information on screening options:
Breast density is an important concept when it comes to screening for breast cancer as it impacts what sort of screening options are most suitable. Dense breast tissue is detectable on a mammogram and often further imaging tests will be recommended
Breast tissue is made up of milk glands, milk ducts, dense supportive tissue and fatty tissue. On a mammogram, the non-dense (fatty) tissue will appear dark and transparent, whereas the dense tissue will appear as a solid white area.
The issue with dense breasts and mammograms is that cancerous lumps, or calcification that is associated with breast cancer, also show up as white on a mammogram. This makes detection very difficult – some liken it to trying to find a snowball in a blizzard.
When a radiologist analyzes a mammogram, they look at the ratio of non-dense tissue to dense tissue and assign a level of breast density. The four categories of breast density that a radiologist uses are:
- Class A (or 1): Fatty
- Class B (or 2): Scattered fibroglandular density
- Class C (or 3): Heterogeneously dense
- Class D (or 4): Extremely dense.
In general, women who are classified as having heterogeneously dense or extremely dense breasts are considered to have dense breasts. This accounts for around half of all women who undergo a mammogram, so from the patient perspective, it’s quite normal to have this classification.
Types of breast cancer screening
There are a few different options for breast imaging available. Typically, imaging begins with mammography and other types of imaging may be recommended if breasts are dense.
Mammography uses x-ray technology to create images of the breast. The most common type of mammogram these days is the digital mammogram, which saves images as digital files for examination.
Taking mammography a step further, there is also a choice between 2D or 3D imaging. 2D is the older technology but it may be all that is available in some places. It is recommended that all women aged 40 and older should have annual mammograms, whether those are 2D or 3D.
3D mammography (or digital breast tomosynthesis) is the newer technology and studies have found it to pick up more cancers than the traditional 2D technology. It also has a lower rate of false positives. A recent study found that 3D screening among women 65 and older lead to improved screening performance metrics.
If a 3D mammogram is combined with a 2D mammogram, then the radiation dose will be doubled. However, this dosage is still lower than FDA’s radiation limit for annual mammograms. What many radiologists do with 3D imaging is to create a synthesized 2D image from the data. This synthesized version has been shown to provide comparable results to digital imaging while reducing radiation dose and image acquisition time.
Where a patient has been assessed as having dense breasts, ultrasound is another potential imaging option that may be recommended. The ultrasound reveals the tissue composition and blood flows, particularly to any potential areas of concern.
An ultrasound uses high-frequency sound waves to produce an image of the anatomy of the breast tissue at the exact location targeted. With the use of a transducer and a thin layer of gel, the procedure creates a picture that shows the radiologist how the sound waves travel through the density, providing an image of the breast tissue.
Ultrasound may be offered in cases such as:
- When a mammogram reveals dense breast tissue and additional screening is recommended.
- When an abnormality is detected that requires further investigation
- When a pregnant woman requires radiation-free screening
- When someone is at high risk for breast cancer and other imaging options (such as MRI) are not appropriate
- When ultrasound-guided biopsy is required.
Ultrasound is safe, non-invasive and doesn’t involve any radiation exposure. There is no special preparation required of patients ahead of their screening.
MBI (Molecular Breast Imaging) or a Miraluma exam is a method for detecting any abnormalities using a radioactive tracer and a gamma camera. It creates a physiological (rather than anatomical) image of breast tissue.
The radioactive tracer “lights up” any areas of cancer inside the breast as cancer cells tend to take up the tracer more than normal tissue does. It has been proven to be an effective tool for cancer detection, although as a relatively recent technology, it isn’t available everywhere.
MBI is more resource-intensive, so it is usually the next step for patients whose ultrasound was inconclusive. (Mammography is the least expensive imaging option).
Some cases where MBI may be recommended include:
- Differentiating between scar tissue and cancer recurrence in patients with a prior history of breast cancer
- Screening high-risk patients who are contraindicated for MRI
- Screening of patients with indeterminate findings from mammography or ultrasound
One limitation of MBI is that it must be timed for the appropriate stage of the menstrual cycle in pre or peri-menopausal women. Patients may need to prepare by fasting for three or four hours before imaging, depending on the protocols of the facility.
One of the first things about MRI as a screening tool is that it is intended to be used with other types of imaging (such as mammogram). It shouldn’t be used as a stand-alone imaging method because although it is sensitive, it can miss some cancers that mammograms will detect. The MRI captures multiple images through magnetic resonance which are then combined using a computer.
The most common use for MRI is after a patient has already had a biopsy and had cancer confirmed. The physician then orders MRI as a means to determine the extent of the disease. MRI may also be recommended when:
- A patient has a suspected rupture of an implant
- A patient has a high calculated risk (greater than 20%) of developing breast cancer
- The patient has a family history of breast and/or ovarian cancer
- The patient has dense breasts
- The patient had radiation treatments to the chest before the age of 30.
Like other types of breast imaging, there is a risk of false positives which may be proven after ultrasound or biopsy. MRI isn’t suitable for patients with metallic implants and like MBI, must be timed with the menstrual cycle. There are no other preparatory requirements.
Know the signs
Early detection, education and support are the top ways in which those affected by breast cancer can improve their chances of long-term survival. This October (and every other month), we encourage you to start by knowing the signs and the options available for screening.
The official screening guidelines from the American Cancer Society are:
- Women ages 40 to 44 should have the choice to start annual breast cancer screening with mammograms (x-rays of the breast) if they wish to do so.
- Women age 45 to 54 should get mammograms every year.
- Women 55 and older should switch to mammograms every 2 years, or can continue yearly screening.
- Screening should continue as long as a woman is in good health and is expected to live 10 more years or longer.
- All women should be familiar with the known benefits, limitations, and potential harms linked to breast cancer screening.
Any woman with a family history, genetic tendency or other factors that may predispose them to breast cancer risk should talk with their physician about appropriate screening. All women should know the signs of abnormalities and immediately report to their physician should they find any.