Circulating tumor cells tied to breast cancer progression during therapy

NEW YORK (Reuters Health) - There is a strong correlation between circulating tumor cell (CTC) levels and radiographic disease progression during systemic therapy for metastatic breast cancer, researchers reported online September 14th in the Journal of Clinical Oncology.

Noting that a blood level of at least 5 CTC per 7.5 mL is said to predict shorter progression-free survival, Dr. Minetta C. Liu of Georgetown University Medical Center, Washington, DC, and colleagues explain that they undertook their study in order to determine whether CTC could also be directly correlated with radiographic progression.

In 68 women starting a new chemotherapy or endocrine treatment regimen for progressive disease, the researchers collected peripheral blood at baseline and at 2- to 3-week intervals. Radiographic studies were performed at 9- to 12-week intervals.

At a median follow-up of 13.3 months, there was a significant correlation between CTC levels and radiographic progression. Women with at least 5 CTCs per 7.5 mL of blood had 6.3 times the odds of radiographic disease progression than patients with fewer CTCs.

The association remained strong when stratified by type of therapy. In addition, patients with 5 or more CTCs at 3 to 5 weeks and at 7 to 9 weeks after the start of treatment had shorter progression-free survival.

Thus, Dr. Liu told Reuters Health, "our findings support the clinical utility of CTC enumeration in conjunction with standard radiographic imaging to more accurately assess treatment benefit and thus may improve patient survival."

"These findings," she concluded, "also suggest the possibility (of improving) patient quality of life by limiting the number of follow-up radiology studies." Asymptomatic patients "with stable or responsive disease and serial documentation of fewer than 5 CTCs per 7.5 mL blood might avoid repetitive scans in the absence of a shift to more than 5 CTCs."

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