Diagnosis

Early detection and treatment are extremely important in curing breast cancer. If an abnormality is found during a routine examination or self examination, there are several tools available to diagnose the disease and determine treatment.

Many women wish to be responsible about screening for breast cancer, especially as incidence of the disease increases and virtually everyone is touched by it, either directly or indirectly. Routine breast screening can detect cancer (abnormal masses) before symptoms appear, and before cancers have a chance to spread — often facilitating treatment early enough to save lives. Yet in the age in which "sound bite" health information can be superficial, unclear, and contradictory, it is easy to become confused about the correct way to proceed. Should one get a mammogram? Should one insist on newer tests such as MRI? What about ultrasound?

Breast Imaging

Mammography

Mammography, Source: American Cancer Society

The goal of screening is to detect cancers at an early stage, before they are palpable and before they have spread. Mammography is the gold standard of breast screening. In use for over thirty years, mammography involves a series of x-rays of the breast. Mammography has been proven in randomized controlled trials to produce statistically significant reductions in death, and women over age 40 should have a screening mammogram every year.

While some women are concerned that the radiation used for mammography might increase the risk of breast cancer, studies involving thousands of women have found the risk of dying of breast cancer significantly decreases for women over 50 who undergo mammography, and there is no evidence that the amount of radiation administered by mammography can actually cause cancer. Mammography is also recommended for most women who have suspicious breast lumps. The probability that a lump contains cancer can be estimated, but a biopsy is needed for certain diagnosis.

In light of the availability of other imaging tools, it is important to consider how sensitive mammography is, and to understand its benefits and limitations. The sensitivity of mammography decreases as the density of the breast increases. Mammograms reveal the density of breast tissue, which is graded on a four-stage scale. Category 1 tissue consists of mostly fat, while category 4 tissue contains little fatty tissue, and almost all fibroglandular tissue. Mammography is 98% sensitive in women with fatty breasts, and 84% sensitive in women with dense breasts. In women under age 50 with a family history of breast cancer, studies have shown that the sensitivity of mammography can be as low as 70%.

One of the great benefits of mammography is its ability to detect microcalcifications. Microcalcification can indicate the presence of ductal carcinoma in situ (DCIS), a very early stage of breast cancer. Microcalcifications are not detected by MRI or by ultrasound.

Mammography Suzanne J. Smith, Director of Breast Imaging, discusses mammography. Length 3:12 min Format Flash Player Required

The Role of Ultrasound

Some studies have shown that ultrasound can enhance cancer detection rates when used in addition to mammography. Ultrasound uses sound waves to create an image of the breast tissue. If an abnormality (such as an area of increased density) appears on a mammogram, ultrasound may be warranted for further evaluation. If a woman has a palpable mass but nothing is detected by mammography, particularly in women with dense breast tissue, ultrasound should be performed.

Ultrasound is not yet considered a routine screening tool because studies have not determined its efficacy compared to mammography. A very large multicenter trial is currently underway to answer this important question.

The Role of MRI

Over the last ten years, MRI, or magnetic resonance imaging, has increasingly been used for evaluation of breast tissue once a woman has a biopsy-proven breast cancer and can help evaluate the extent of disease in that breast. It can help answer questions such as, Are there other areas of abnormal tissue near the biopsy-proven cancer? Are there areas of abnormal tissue in other quadrants of the breast? Is there a cancer in the other breast?"

Nevertheless, even MRI has its limitations. There is a high false positive rate, which can lead to unnecessary biopsies and patient anxiety, and multiple follow-up exams.

Breast MRI, Source: Dr. Steven Harmes. Baylor University Medical Center, Dallas Texas

As a screening tool, MRI is most appropriate for patients at high risk. This category includes women who have at least a 20-25% chance of developing breast cancer:

• those with mutations of BRCA1/2 genes;
• women who have Hodgkins disease and have had radiation to the thorax;
• women with a family history of breast cancer (mother, daughter, sister); or
• women who have had breast cancer and;
• in some cases, women with biopsy-proven high-risk lesions, atypia, or lobular carcinoma in situ may be considered for MRI.

Breast imaging and breast screening can be complex and must involve dialogue with one's physicians. Mammography may be sufficient for one patient, but not for another. There is often no simple answer, and no 'cookie cutter' approach.

Biopsy

A doctor can usually perform a needle biopsy in the office. A local anesthetic is injected into the breast, and light suction is applied through a hollow needle inserted into the lump to remove a sample of tissue or aspirate fluid. Disappearance of the lump after fluid is withdrawn usually indicates a benign cyst. Nevertheless, the fluid is sent to a laboratory for analysis. If no abnormal cells are found, no further tests are required. In some cases, a surgical excision may be necessary. This procedure entails removal of the lump and small amounts of surrounding tissues for laboratory analysis. A surgical biopsy usually is done in a hospital (often as out-patient surgery) using either local or general anesthesia. About 80 percent of biopsies show no cancerous cells.

In accordance with guidelines set forth by the American Cancer Society, we recommend that women with a lifetime risk for developing breast cancer greater than 20% get an MRI in addition to their mammogram every year. Women with a 15-20% lifetime risk should discuss MRI screening with their doctors. The ACS does not recommend MRI screening for those with a lifetime risk less than 15%.

Additional Tests

When a tumor is found, estrogen-receptor and progesterone-receptor assays are used to determine whether the tumor is dependent on estrogen or progesterone (estrogen- or progesterone-receptor positive). Additional tests sometimes performed measure the rate at which tumor cells are dividing (DNA flow cytometry) and the presence of abnormal genes such as one called Her 2/Neu.