A UC Davis Health team of surgeons and scientists has integrated a novel imaging technology with robotic surgical systems to help detect primary cancerous tissue during head and neck cancer surgeries. The technology, known as Fluorescence Lifetime Imaging (FLIm), allows surgeons to identify and remove malignant primary tumors more precisely and thoroughly.

In a study published in Head and Neck journal, the team shared the results of testing FLIm in six patients with squamous cell carcinoma of unknown primary in the head and neck.

“Depending on the diagnostic and clinical capabilities of medical institutions, up to 50% of primary tumors may remain undiscovered for patients with this type of cancer,” said Andrew Birkeland, M.D., assistant professor in the Department of Otolaryngology-Head and Neck Surgery and the UC Davis Comprehensive Cancer Center and coauthor of the study. “Missing the primary tumors might put patients at risk of cancer spread and death.”

What is squamous cell carcinoma of unknown primary in the head and neck?

Head and neck squamous cell carcinoma of unknown primary origin, also known as occult primary, is a clinical scenario when metastatic carcinoma is identified in the neck’s lymph nodes, but the primary tumor location is not identified by standard imaging or clinical exam methods.

Around 2600 new cases of occult primary cancer are identified each year in the U.S. In most cases, especially those related to the human papillomavirus (HPV), the primary site is suspected to be in the palatine tonsils and the lingual tonsils of the base of tongue. These cancers are less likely to be associated with tobacco and alcohol abuse.

Integrating imaging technology into transoral robotic surgeries

Transoral robotic surgical platforms (TORS), such as the da Vinci® Surgical System, allow for minimally invasive surgeries to detect and remove tumors from hard-to-reach areas in the head and neck. To improve decision-making during surgeries and enhance the detection of elusive tumors, new diagnostic technologies compatible with TORS are needed.

“If surgeons can identify and visualize metabolic changes in tissue during the operation, they can precisely remove cancerous tissues and improve the patient’s survival,” Birkeland said.

What is FLIm and how does it work?

FLIm was developed at the University of California, Davis. The technology allows for the objective visual detection of tumors using the tissue’s intrinsic fluorescence properties. The surgeon scans the tissues for fluorescent changes related to alterations in tissue metabolism, a factor strongly linked to cancerous tumors. The FLIm device captures and analyzes the intrinsic light emitted by the tissues and provides visual and quantitative data of the autofluorescence light.

The technology has showed benefits in the diagnosis and surgical guidance in brain and breast cancer surgeries and potential in identifying heart disease.

Findings

The team integrated FLIm into a transoral robotic system to acquire optical data on the oropharyngeal tissues of patients with head and neck carcinoma of unknown primary origin. The combined robotic-imaging power captured and analyzed tissue autofluorescence to differentiate tissue types.

The team first used a dataset of 55 patients with known primary tumors to train a machine learning classifier and develop a model that can accurately identify the presence and location of occult cancer using FLIm tissue autofluorescence.