A blood test that can detect circulating DNA from cancer cells appears to accurately predict the risk of a breast cancer recurrence 8 months earlier than standard detection methods among women with high-risk breast cancer. However, further study is necessary to confirm these findings and understand their benefit in a clinical setting. These results were recently published in the journal Science Translation.
Following standard therapy for early breast cancer, women undergo tests and scans to ensure that no detectable cancer remains. Thereafter, these patients continue to undergo periodic screening on a regular basis, with greater frequency during the period immediately following completion of treatment. These screenings are to detect a potential recurrence in its earliest stages, at which time treatment provides optimal chances for a cure.
Currently, standard clinical methods for the detection of recurrences are not able to detect small amounts of cancer cells. It is these undetectable cells that can lead to recurrences. Healthcare providers continue to explore novel ways in which to predict which patients are at a higher risk of developing a recurrence so that treatment can be individualized and tailored towards a cure.
Among women who are at a high risk of developing a cancer recurrence, achieving maximum cure rates might require a more aggressive therapeutic approach than for those who are at a lower risk for developing a recurrence. This is due to the fact that among women who are at a low risk of experiencing a recurrence, more aggressive therapy has the potential to cause serious risks from side effects without achieving a survival benefit.
Cancer cells tend to release some segments of their DNA into a patient’s circulating blood. This DNA is referred to as ctDNA, which often harbors specific mutations. Through novel laboratory methods, ctDNA is identified in the blood even when other standard clinical tests do not possess the capabilities of detecting such small quantities of cancer.
Researchers recently conducted a study to explore the potential accuracy of the presence of ctDNA in determining the risk of a breast cancer recurrence. The study included 55 women who had received chemotherapy prior to the surgical removal of their early cancer (neoadjuvant therapy), and were considered to be at a high risk of developing a recurrence based upon standard clinical measures.
- 19% of patients had ctDNA identified in a blood sample drawn as early as 2 to 4 weeks following surgery. Of these patients, 86% experienced a subsequent cancer recurrence.
The researchers also performed “mutation tracking” in 15 patients. Mutation tracking refers to testing for ctDNA every 6 months.
- Women with ctDNA detected through mutation tracking were at a risk for a recurrence that was 12 times higher than women with no ctDNA detected.
- 96% of patients who did not experience a recurrence had no detectable ctDNA through mutation tracking.
- The ctDNA levels prior to completion of therapy did not correlate to the risk of a recurrence. In addition, ctDNA levels were not predictive of cancer spread to the brain.
The researchers cautioned that these are very early results, and only further study can determine if ctDNA detection, which could possibly result in more tailored treatment, would lead to improved survival in this group of women.
Furthermore, the researchers stated that it is not yet known whether breast cancer patients considered to be at a low risk of a recurrence would benefit from this testing.
However, these results appear to provide potential in using ctDNA to help predict the risk of cancer relapses among women with early, high-risk breast cancer, particularly as ctDNA was detected an average of 8 months prior to detection of relapses with standard methods.
Reference: Garcia-Murillas, Schiavon G, Weigelt B, et al. Mutation tracking in circulating tumor DNA predicts relapse in early breast cancer. Science Translational Medicine. 2015; 7 (302): 302ra133. DOI: 10.1126/scitranslmed.aab0021.
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