Clinical application of molecular profiling in breast cancer

The study of sirtuins in breast cancer patients before and after radiotherapy

Background/aim

Targeting the new and unique proteins is an important medical strategy for treating breast cancer. It is quite important to find out proteins that have a role in the development of cancer. Sirtuins (SIRT) are well related in different physiological activities and connected with cancer. We aimed to determine the effect of radiotherapy on SIRT1 and SIRT2, which have not been yet been clarified as a tumor suppressor or promoter.

Materials and methods

Twenty-two women with nonmetastatic breast cancer enrolled in the study. Blood samples were taken before and after radiotherapy, soluble SIRT1 and SIRT2 levels were determined with ELISA kits.

Results

There was no difference in SIRT1 levels before and after radiotherapy (p = 0.548). SIRT2 levels were significantly found to be decreased after radiotherapy (p = 0.042). There was a strong and positive correlation before radiotherapy (p < 0.001), and a moderate and positive correlation after radiotherapy (p = 0.007) between SIRT1 and SIRT2.

Conclusion

These results suggest that SIRT2 may provide a new strategy for follow-up of breast cancer treatment. Additionally, by emphasizing the importance of SIRT2 in breast cancer, it opens ways to provide grounds for the development of the next generation of SIRT2-specific radiotracers. Finally, the most important thing, in fact, the positive correlation between SIRT1 and SIRT2 both before and after radiotherapy, appears to be clear evidence suggesting more oncogenic roles of sirtuins.

Breast cancer expression profiling: the impact of microarray testing on clinical decision making

The available clinical prognostic tools show an obvious limitation in predicting the outcome of breast cancer patients, and pathological features cannot classify tumours accurately. Microarray-based molecular classification of breast tumours or selection of gene expression panels to improve risk prediction or treatment outcomes are thought to be theoretically superior to established clinical and pathological criteria, based on guidelines such as the St Gallen and National Institute of Health consensus, or which use specific prognostic tools, such as the Nottingham Prognostic Index or Adjuvant-Online algorithm. Although two diagnostic tests based on gene expression profiling of breast cancer are commercially available, a new molecular classification and molecular forecasting of breast cancer based on expression profiling cannot outperform the standard tumour diagnostic at present. This review focuses on some important problems in the practical application of molecular profiling of breast cancer for clinical purposes.

Clinical Trial Designs for Prospective Validation of Biomarkers

Traditionally, anatomic staging systems have been used to determine predictions of individual patient outcome and, to a lesser extent, guide the choice of treatment in patients with cancer. With new targeted therapies, the role of biomarkers is increasingly promising, suggesting an integrated approach using the genetic make-up of the tumor and the genotype of the patient for treatment selection and patient management. Specifically, biomarkers can aid in patient stratification (risk assessment), treatment response identification (surrogate markers), or in differential diagnosis (identifying individuals who are likely to respond to specific drugs). To be clinically useful, a marker must favorably affect clinical outcomes such as decreased toxicity, increased overall and/or disease-free survival, or improved quality of life. This paper focuses on possible clinical trial designs for assessing the utility of a predictive marker(s) for toxicity or clinical efficacy. We consider the scenario of single and multiple markers as well as present alternative solutions based on the prevalence of a marker. Our designs rest on the assumption that the methods for assessment of the biomarker are established and the initial results show promise with regard to the predictive ability of a marker. Additional research is clearly warranted to achieve the goal of 'predictive oncology'.