Predicting drug metabolism

Another type of test that may prove important is the assessment of inherited genetic variation that influences drug metabolism (the processing of drugs by the body). In the case of tamoxifen, for example, differences in effectiveness may be explained at least in part by inherited differences in a gene known as CYP2D6.[3] Most people have two functional versions of this gene and are able to effectively process tamoxifen. Some people, however, have versions of this gene that are less effective at processing tamoxifen. Testing patients for these gene variants could help doctors identify patients who are less likely to respond to tamoxifen. A currently available test is AmpliChip®, which assesses CYP2D6 as well as CYP2C19 (another gene involved in drug metabolism). Additional data are required, however, before formal recommendations can be developed about this type of testing.[4]
For more information about AmpliChip, visit http://www.amplichip.us/.

Learn More 

Patients who have already undergone surgery and lymph node evaluation and know their stage of cancer may select from the options below. In order to learn more about surgery and sentinel lymph node dissection, go to Surgery for Breast Cancer.
Carcinoma In Situ: Approximately 15-20% of breast cancers are very early in their development. These are sometimes referred to as carcinoma in situ and consist of two types: ductal carcinoma in situ (DCIS), which originates in the ducts and lobular carcinoma in situ (LCIS), which originates in the lobules. DCIS is the precursor to invasive cancer and LCIS is a risk factor for developing cancer.
Stage I: Cancer is confined to a single site in the breast, is less than 2 centimeters (3/4 inch) in size and has not spread outside the breast.
Stage IIA: Cancer has spread to involve underarm lymph nodes and is less than 2 centimeters (3/4 inch) in size or the primary cancer itself is 2-5 centimeters (3/4-2 inches) and has not spread to the lymph nodes.
Stage IIB: Cancer has spread to involve underarm lymph nodes and/or the primary cancer is greater than 5 centimeters (2 inches) in size and does not involve any lymph nodes.
Stage IIIA: Cancer is smaller than 5 centimeters (2 inches) and has spread to the lymph nodes under the arm or the lymph nodes are attached to each other or to other structures or the primary cancer is larger than 5 centimeters (2 inches) and has spread to the lymph nodes under the arm.
Stage IIIB: Cancer directly involves the chest wall or has spread to internal lymph nodes on the same side of the chest.
Inflammatory: Inflammatory breast cancer is a special class of breast cancer that is rare. The breast looks as if it is inflamed because of its red appearance and warmth. The skin may show signs of ridges and wheals or it may have a pitted appearance. Inflammatory breast cancer tends to spread quickly.
Stage IV: Cancer has spread to distant locations in the body, which may include the liver, lungs, bones or other sites.
Recurrent/Relapsed: The breast cancer has progressed or returned (recurred/relapsed) following an initial treatment.

References:

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[1] American Cancer Society. Cancer Facts & Figures 2009. Available at: http://www.cancer.org/docroot/stt/stt_0.asp (Accessed July 14, 2009).

[2] Albain K, Barlow W, Shak S et al. Prognostic and predictive value of the 21-gene recurrence score assay in postmenopausal, node-positive, ER-positive breast cancer (S8814,INT0100). Presented at the 30^th Annual San Antonio Breast Cancer Symposium. San Antonio, TX, December 13-16, 2007. Abstract #10.

[3] Schroth W, Antoniadou L, Fritz P et al. Breast cancer treatment outcome with adjuvant tamoxifen relative to patient CYP2D6 and CYP2C19 genotypes. Journal of Clinical Oncology. 2007;25:5187-5193.

[4] Desta Z, Flockhart DA. Germline pharmacogenetics of tamoxifen response: have we learned enough? Journal of Clinical Oncology. 2007;5147-5149.