Understanding the Biology of Breast Cancer

Christine Wilson, cancer survivor, shares her experiences from the Abramson Cancer Center’s 2011 Update in Breast Cancer: Coverage of the American Society of Clinical Oncology (ASCO) Annual Meeting CME/CE Certified Course. The course is under the direction of Kevin Fox, MD, medical director of the Rena Rowan Breast Center. This is the second of four posts about the latest findings in treating breast cancer. 

One of the larger trends in cancer treatment, especially breast cancer treatment, is the increasing ability to identify biologic subtypes of the disease and the need for better prognostic biomarkers, or biomarkers that provide information regarding outcome without regard for therapy.

Angela DeMichele, MD, MSCE

At the 2011 ASCO conference, Angela DiMichele, MD, MSCE, assistant professor of medicine and epidemiology at the Perelman School of Medicine at the University of Pennsylvania, talked about the important role biology plays in identifying these markers. As co-program leader of the Abramson Cancer Center's National Cancer Institute (NCI)-approved breast cancer program, she discussed one such marker, Ki-67, and intrinsic genetic subtypes.

Two studies (Abstracts 500 and 501) provide support for the validity of Ki-67 as a means of identifying highly proliferative tumors and those that are more likely to respond to specific chemotherapy regimens. Ki-67 is a cancer antigen that is found in growing, dividing cells but is absent in the resting phase of cell growth. This characteristic makes Ki-67 a good tumor marker. This test is done on a sample of tumor tissue, to help predict your prognosis.

Many studies have been done to determine Ki-67's value as a tumor marker test. Researchers agree that high levels of Ki-67 indicate an aggressive tumor and predict a poor prognosis and tumors that tested positive with high levels of Ki-67, have a higher risk of recurrence.

Perhaps more intriguing is the emergence of intrinsic subtypes of breast cancer. Gene expression studies have identified several distinct breast cancer subtypes. The value of this information is less clear, but understanding the specific biologic characteristics that influence these subtypes may help determine which patients will respond to which therapies.

Cancer researchers now understand that breast cancer is a spectrum of diseases, ranging from those that are more endocrine driven to those that are more chemosensitive. These findings reinforce the need for accurate molecular profiling for all breast cancer patients.

OncotypeDX has become a standard means for molecular profiling and guiding breast cancer treatment decisions, but another, potentially even more comprehensive tool is on the horizon. PAM-50 screens for 50 genes and is potentially more sensitive, but is not yet clinically available. Further studies are needed to validate its use.

Abstracts can be found on the 2011 ASCO meeting website.

Learn more about breast cancer treatment at Penn’s Abramson Cancer Center.

Are you at risk for breast cancer? Attend Penn Women’s Cancer Conference – Focus on Your Risk of Breast/Ovarian Cancer

Are you a breast cancer survivor? Attend the Penn Women’s Cancer Conference – Life after Breast Cancer

Coming up next, How Weight and Hormones Affect Breast Cancer Outcomes.