Abstract
BACKGROUND: Circulating tumor cells (CTCs) form metastases in distant organs. The purpose of this research was to determine if tumor manipulation could enhance cancer cell release from the primary tumor into the circulatory system. METHODS: Nude mice were inoculated with melanoma or breast cancer cells. The implanted tumor underwent compression, biopsy, complete resection, or laser treatment. CTCs were monitored in the bloodstream using in vivo photoacoustic and fluorescence flow cytometry. RESULTS: We discovered that pressure, biopsy, and laser treatment can dramatically increase CTC counts (up to 60-fold), whereas proper tumor resection significantly decrease CTC counts. CONCLUSION: Standard medical procedures could trigger CTC release that may increase the risk of metastases. This finding suggests the guidance of cancer treatment and likely diagnosis by real-time monitoring of CTC dynamics followed by well-timed treatment to reduce CTCs in the blood. In vivo detection of intervention-amplified CTCs could be used for early diagnosis of a small tumor, which is undetectable with conventional methods.