Breast Cancer Basics
Invasive Breast Cancer Staging
To assess prognosis and to guide treatment decisions, as well as research, breast cancer is generally assessed using a system called staging. Invasive breast cancer tumor stages range from Stage I to Stage IV, with Stage I having the best prognosis and Stage IV having the poorest. The breast cancer staging system takes into account three major features of a woman's breast cancer:
- Breast cancer tumor size
- Lymph node status
- Metastasis status
Non-Invasive Breast Cancer & DCIS
DCIS is an early or pre-invasive form of breast cancer, sometimes referred to as Stage 0 breast cancer. Unlike invasive breast cancer, the tumor cells in DCIS are confined to the milk ducts within the breast.
Breast Cancer Tumor Size
Breast Cancer tumor size can be an important indicator of how quickly a tumor is growing. However, a small tumor may be small because it is growing very slowly, or because it was growing quickly but was found early. Tumor size is only one of many factors used to indicate whether a woman's breast cancer is more or less aggressive.
Lymph Node Status
Lymph node status indicates whether any breast cancer cells have moved from the original tumor into the lymph nodes. Lymph nodes are found throughout the body, and make up part of the lymphatic system, which is part of the body's immune system. If breast cancer does spread, it usually spreads first to the lymph nodes under the arm on the side of the breast cancer.
If lymph node status is positive, meaning the lymph nodes contain breast cancer cells, the cancer may be more likely to return or recur.
If the lymph node status is negative, meaning that the lymph nodes appear free of breast cancer cells, the breast cancer is less likely to recur.
Breast Cancer Tumor Histologic Grade
Pathologists are doctors who are experts in diagnosing disease and who study both the overall and microscopic appearance of the tumors of women with breast cancer. In addition to the stage, pathologists classify tumors into one of three grades based on how similar in appearance the breast cancer cells are to normal cells, and on how many of those tumor cells are dividing. The greater the number of cells dividing, the higher the breast cancer tumor grade. Tumor grade is one of many factors that, when used in combination, can indicate how aggressive someone's breast cancer is.
Grade 1: Breast cancer tumor cells are more similar to normal cells and grow slowly (also called well-differentiated).
Grade 2: Breast cancer tumor cells are somewhat abnormal and growing at moderate speed (also called moderately differentiated).
Grade 3: Breast cancer tumor cells are abnormal and growing quickly (also called poorly differentiated).
Hormones are naturally occurring chemicals in the body that stimulate the growth of hormone-sensitive tissues, such as those in the breast. In some cases of breast cancer, the hormones estrogen and progesterone may stimulate tumor growth. To find out if your cancer is hormone-dependent, your doctor will likely have your tumor tissue tested for the presence of hormone receptors, which are proteins on the surfaces of cells to which hormones bind, thus activating tumor growth.
If your breast cancer is estrogen receptor-positive (ER+) or progesterone receptor-positive (PR+), meaning it has receptors for those respective hormones, you may be a candidate for hormonal therapy.
Human epidermal growth factor receptor 2 (HER2/neu) is a protein that appears in the cancer cells of some women with breast cancer. Approximately 20%-40% of women with breast cancer show HER2 overexpression (gene amplification), which correlates with poor prognosis and is predictive of response to trastuzumab.1
A woman whose tumor has greater-than-normal levels of HER2/neu is considered HER2-positive. A woman whose tumor has normal levels of HER2/neu is considered HER2-negative.
Genomic Testing - Oncotype DX®
Genomic tests look at groups of genes and how active they are within a tumor. This activity can influence how breast cancer is likely to grow and respond to treatment. For example, the Oncotype DX® test looks at a group of genes and their activity in breast tumor tissue. Validation studies have already been performed on the Oncotype DX Breast Cancer Assay for patients with pre-invasive or DCIS, node-negative and node-positive, estrogen-receptor-positive (ER+) breast cancer; for single gene reporting quantitative of ER (estrogen receptor), PR (progesterone receptor negative) and HER2 (human epidermal growth factor receptor 2) genes, and for patients treated with Tamoxifen or an Aromatase Inhibitor. The Oncotype DX breast cancer tests are currently commercially available. For detailed information please call: (866) ONCOTYPE or visit www.oncotypedx.com
Breast Cancer Recurrence And Metastasis
Recurrence is the return of the same cancer after initial breast cancer treatment. Therapy for early-stage breast cancer aims to reduce the chance that cancer will return, or recur. It is valuable to know the chance that your particular breast cancer will return, because that can help you and your doctor determine whether additional treatment beyond surgery is appropriate.
There are two main types of recurrence:
Local recurrence is the return of cancer to the area where a woman originally had cancer and subsequent surgery. Signs of local recurrence of breast cancer usually become apparent during mammograms, physical examinations by a health professional or self-examinations. Local recurrence is often treated similarly to the way the original cancer was treated: with surgery, followed by radiation therapy (if it was not done initially), chemotherapy and/or hormonal therapy.
In distant recurrence, the cancer metastasizes, or spreads to parts of the body other than the original location (breast or lymph nodes located near the breast). Symptoms such as bone pain, weight loss, and shortness of breath may be signs of distant recurrence. If cancer does metastasize, it commonly spreads to the lungs, bones, liver or brain.
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Source For This Page:
Bonadonna, Gianni, Gabriel N. Hortobagyi, and A. Massimo Gianni, eds. Textbook of Breast Cancer: A Clinical Guide to Therapy. 2nd ed. London: Martin Dunitz, 2001.
1. HER2 information appears on p. 56 of the above-referenced work. Trastuzumab (HERCEPTIN®), as part of a treatment regimen containing doxorubicin, cyclophosphamide, and paclitaxel, is indicated for the adjuvant treatment of HER2-overexpressing breast cancer. HERCEPTIN as a single agent is indicated for the adjuvant treatment of HER2-overexpressing node-negative (ER/PR-negative or with one high-risk feature) or node-positive breast cancer, following multi-modality anthracycline-based therapy. Lapatinib (TYKERB®) is indicated in combination with capecitabine (XELODA®) for the treatment of patients with advanced or metastatic breast cancer whose tumors overexpress HER2 and who have received prior therapy including an anthracycline, a taxane, and trastuzumab (HERCEPTIN®).
HERCEPTIN is a registered trademark of Genentech, Inc.
TYKERB is a registered trademark of GlaxoSmithKline.
XELODA is a registered trademark of Roche Laboratories Inc.
i Hughes et al, J Clin Oncol. 2009; 27:39