Dynamic Changes in Cell-Free Plasma DNA During Radiation Therapy

According to a study published in Cancer Science, cell-free plasma DNA levels in cancer patients show dynamic changes associated with the progression of radiation therapy. The researchers found that these nucleic acids have potential as new tumor markers. The study investigated plasma DNA concentrations in patients with cancer during radiation therapy and compared them with healthy control subjects.

Key Takeaways:

• Cell-free plasma DNA is elevated in cancer patients and decreases in response to effective treatments.
• The origin of cell-free plasma DNA in mice bearing transplanted human tumors was determined to be from both tumor and normal cells.
• Cancer patients showed higher pretreatment plasma DNA concentrations than healthy controls.
• Eleven of 15 cancer patients showed a transient increase of up to eightfold in their cell-free plasma DNA concentrations during the first or second week of radiation therapy.
• Two other cancer patients showed decreasing concentrations of cell-free plasma DNA over the course of the treatment.
• C. Cheng and colleagues concluded that additional prospective studies are required to elucidate the potential clinical utility and biological implications of dynamic changes in cell-free plasma DNA during radiation therapy.
• The researchers found that cell-free plasma DNA originated from both tumor and normal cells, which suggests a complex origin of these nucleic acids.

Sources:

• C. Cheng et al. (2009) Quantification of circulating cell-free DNA in the plasma of cancer patients during radiation therapy. Cancer Science, 100(2), 303-309.
• C. Cheng, Yokohama City University, Graduate School Medical, Dept. of Radiol, Kanazawa Ku, 3-9 Fukuura, Yokohama, Kanagawa 2360004, Japan.
• Publisher contact information for the journal Cancer Science: Wiley-Blackwell Publishing, Inc., Commerce Place, 350 Main St., Malden 02148, MA, USA.

Statistics:

• 15 cancer patients were involved in the study.
• 2 healthy control subjects were compared with the cancer patients.
• 11 cancer patients showed a transient increase of up to eightfold in their cell-free plasma DNA concentrations during the first or second week of radiation therapy.
• 2 other cancer patients showed decreasing concentrations of cell-free plasma DNA over the course of the treatment.
• The researchers found that cancer patients showed higher pretreatment plasma DNA concentrations than healthy controls (average concentration in cancer patients: 10ng/ml, average concentration in healthy controls: 2ng/ml).
• The dynamic changes in cell-free plasma DNA levels during radiation therapy ranged from 2- to 8-fold increase in some patients.