Breast cancer affects 180,000 women each year, and 40,000 of them die from this disease annually. Unfortunately, advanced or metastatic breast cancer is not curable. Therefore, emphasis must be directed toward early detection.
Early detection of breast cancer
Although widespread screening for breast cancer without symptoms (called asymptomatic breast cancer) remains controversial, this disease is appropriate for screening for these reasons:
- The high rate of breast cancer in the Western population
- The long preclinical phase of breast cancer — The preclinical phase is the stage in a disease when a specific diagnosis cannot be made because adequate signs and symptoms have not yet developed.
- The increased effectiveness of treatment for early-stage disease
Typically, the doubling time of breast cancer is approximately 100 to 200 days. Therefore, the preclinical lead time gained by mammographic screening is two to four years more than with the physical detection of breast cancer.
Mammography for early breast cancer detection
At this time, mammography is our best screening test for the early detection of breast cancer. It has a sensitivity of detecting breast cancer equal to 80 percent, and a specificity rate of greater than 95 percent. Mammography is associated with almost no increased risk of radiation-induced cancer development. Unfortunately, mammography for breast cancer detection is not perfect: 15 percent to 20 percent of early cancers are not detected. Recent standardization of mammographic interpretation and radiographic technology will improve these values.
The current recommendations for mammographic screening have become controversial. Annual mammograms performed in women from age 50 to 69 have been demonstrated to reduce breast cancer mortality by 30 percent. Some studies have also demonstrated a 22 percent to 49 percent reduction in breast cancer mortality among women from age 40 to 49 who have annual mammograms.
In addition, more than 40 percent of the years of life lost to breast cancer are in women who are younger than 50 years old. For this reason, ongoing research is attempting to study the effectiveness of early breast cancer detection by mammographic screening among women younger than 50 years old. According the American Cancer Society, the current recommendations for mammography in women ages 40 to 49 is still yearly. Women who are under the age of 50 and have considerably dense breasts may benefit from digital mammography, a newer way to visualize dense breast tissue.
The focus on early breast cancer detection has broadened the eligibility of some women to receive adjuvant therapy. Adjuvant therapy is defined as "treatment given in addition to surgery." This type of therapy includes chemotherapy or hormonal therapy, such as therapy with tamoxifen (a nonsteroidal anti-estrogen drug) or with an aromatase inhibitor.
Surgical treatment only addresses control of the local disease, and does not have an impact upon the risk for distant disease or advanced disease (metastasis). Options for local disease control include:
- Modified radical mastectomy (removal of the breast and sampling of the lymph nodes in the axilla, or armpit)
- Lumpectomy (removal of the primary breast cancer) with a sampling of the lymph nodes in the axilla and radiation therapy to the breast
- Sentinel node biopsy (a sampling of the first 3 to 5 lymph nodes in the axilla)
Leaders in the field of breast cancer recently discussed recommendations for adjuvant treatment of early stage breast cancer in hopes of increasing the rate of cure for this disease. The incidence of small (measuring < 1 cm) screening-detected cancer is increasing. These patients have a 10 percent or less risk of dying from breast cancer and might not benefit from adjuvant therapy.
Patients should receive chemotherapy if lymph node involvement is present. A gene array test called Oncotype DX® can help to determine if chemotherapy will benefit the patient by determining a recurrence score. This score determines the likelihood of the cancer coming back. If the score is high, the woman will benefit from chemotherapy. If the recurrence score is low, the woman will not benefit from chemotherapy.
Patients whose cancer does not involve the lymph nodes should be divided into good risk or high risk, depending upon tumor characteristics. Tamoxifen or chemotherapy with CMF (Cytoxan®, methotrexate, 5FU) might be offered. Taxol®, another chemotherapy agent, may also be used. Herceptin® is used in tumors which are HER-2neu positive.
Great advances have been made in the field of breast cancer, specifically in early detection and the application of adjuvant therapy. These advances have rendered early stage breast cancer a curable disease. More research is needed, however, and further advances can only be made with the participation of patients in clinical trials.