Laparoscopy technique lights up invisible metastases

By Lynda Williams

Fluorescence laparoscopy (FL) could be the way forward for cancer surgery and staging, say researchers writing in the Archives of Surgery.

"Enhancing a surgeon's ability to identify primary and metastatic tumors and distinguish tumors from surrounding vital structures, makes FL an exciting and important development," write Michael Bouvet (University of California, San Diego, USA) and co-authors.

The team used a mouse model of human colorectal cancer to demonstrate the technique's ability to reveal the presence of metastases during surgery that are undetectable with bright field laparoscopy (BL).

Colon cancer cells expressing green fluorescent protein (GFP) were administered by intracecal injection into 12 nude mice to create models of early and late metastatic disease after 2 and 4 weeks, respectively.

The researchers compared the number of metastases detected in the four abdominal quadrants at the two time points using BL and FL laparoscopy. Open FL (OL) after the animals were sacrificed was used as a positive control.

FL identified significantly more OL-detected metastases than BL in both the early (90 vs 12%) and late (86 vs 35%) mouse models, Bouvet et al report.

Moreover, FL detection of metastases did not significantly differ from that of OL at either disease stage, whereas BL was significantly poorer than OL for both early and late disease.

The team says that monoclonal antibody drugs to treat cancer and other diseases have paved the way for clinical use of fluorescent chimeric antibodies in FL.

"Alternatively, the bright fluorescence of GFP can be selectively delivered to tumors via a cancer cell-selective telomerase-dependent adenovirus," the researchers suggest.

They conclude: "The use of FL enables the identification of metastases that would otherwise be missed using standard laparoscopy.

"FL could then be used not only in staging laparoscopy but also to improve the localization of liver metastases for resection or radiofrequency ablative techniques."

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