The findings of several recent studies involving breast cancer is lending further evidence to the idea that genetics and genomics will soon be the primary focus of diagnosing and treating cancer. Although the findings offer no new clinical tools, the results are strengthening the evidence pool on which eventual personalized treatment of cancers will be based.
In an analysis of 2000 frozen samples of breast cancer tumors, scientists discovered that breast cancer could be classified into 10 distinct subgroups according to common genetic features, with each subgroup associated with different outcomes for patients.1 This finding may help explain why tumor response to treatment is so varied. Additional research is needed to better understand how tumors of each subgroup behave and to which treatments they respond.
In another new study, researchers discovered significant genetic diversity in cells shed by cancerous tumors into the bloodstream.2 Using blood samples from patients with breast cancer, researchers identified and studied individual circulating tumor cells rather than looked at the average of many cells—a first, according to the study authors. The study is also the first of its kind to show extensive genetic differences between circulating tumor cells, which can express genes that potentially could predict a tumor’s response to a specific treatment.
High levels of methylation—modification of the ataxia telangiectasia mutated (ATM) gene, which functions to control the rate at which genes grow—might be a marker of breast cancer risk, according to results of a new case-control study.3 Among 3 studies involving a total of approximately 640,000 women, 640 cases of breast cancer and 780 healthy control subjects were identified. In 2 of the studies, when compared with the healthy control group, the breast cancer group had significantly higher average levels of methylation at a particular point on the ATM gene. This pattern was strongest for women younger than 59 years. According to the study authors, the identification of a white blood cell DNA methylation marker for breast cancer, which can be detected in a blood sample (vs a tissue sample), could allow for the development of a simple blood test to determine risk of breast cancer.
•There is no blood test available for breast cancer risk at this time or in the foreseeable future, but the possibilities are intriguing.
•The identification of 10 different subgroups of breast cancer has no effect on the current standard of care but offers promising evidence for the future possibility of personalized cancer care.
1. Curtis C, Shaw SP, Chin SF, et al. The genomic and transcriptomic architecture of 2,000 breast tumours reveals novel subgroups.
Nature. 2012:10.1038/nature 10983. [Epub ahead of print.]
2. Powell AA, Talasaz AH, Zhang H, et al.
Single cell profiling of circulating tumor cells: transcriptional heterogeneity and diversity from breast cancer lines.
PLoS One. May 7, 2012. Accessed May 8, 2012.
3. Brennan K, Garcia-Closas M, Orr N, et al. Intragenic ATM methylation in peripheral blood DNA as a biomarker of breast cancer risk.
Cancer Res. 2012;72:2304-2313.