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Colorectal cancer is the third most common cancer in the United States, with approximately 140,000 new cases each year. Early diagnosis and surgical removal of benign neoplastic lesions is an effective method for reducing a patient’s cancer risk and preventing cancer-related death. The current standard for screening is conventional colonoscopy, which relies on visual inspection of the lining of the intestines.
The BTTC, in collaboration with Dr. Karim Alavi in the Division of Colorectal Surgery at UMass Medical School in Worcester, is evaluating the tissues’ intrinsic contrast, combining it with the center’s existing efforts on terahertz waveguide development.
“We have shown that polarized terahertz images can differentiate between healthy and cancerous tissues,” notes UMass Lowell physics Prof. Robert Giles, the center’s director. “Moreover, the contrast ratio in this modality appears to be preserved across different patients. Thus, this technique potentially offers surgeons a tool to aid in colon-cancer screening.
Non-melanoma skin cancer accounts for half of all cancers in the country. Of the more than 3.5 million cases diagnosed each year, about 3,000 patients die from the disease. And the cost of treatments exceeds $600 million annually. The most effective treatment usually involves Mohs micrographic surgery, in which the doctor removes the tumor by excising the tissue layer by layer, with each layer examined under a microscope to help map the diseased area. This ensures the complete removal of the tumor while at the same time preserving much of the surrounding normal tissue. While the procedure is effective, it is also time-consuming, labor-intensive and costly.
Terahertz imaging has been shown to offer intrinsic contrast—i.e., no external contrast agent needs to be applied—between normal and cancerous skin. However, its resolution is limited in wavelength to approximately 0.5 millimeters. Imaging with optical polarized light offers higher resolution (comparable to histology) but lacks the contrast. This is the reason why BTTC researchers are collaborating with UMass Lowell physics Assoc. Prof. Anna Yaroslavsky of the university’s Advanced Biophotonics Laboratory (see page 7) to explore a combination of optical and terahertz imaging for non-melanoma skin cancer that would complement current treatment techniques.
The panel shows optical photographs (a) and (d) and cross-polarized terahertz reflection images (b) and (c) of fresh normal (N) versus cancerous (C) tissues from a human colon.
“As a non-invasive imaging modality capable of detecting cancer margins intra-operatively, this imaging technique can eliminate the need for simultaneous histological/pathological examination of the tissue samples under the microscope, greatly simplifying treatment,” explains BTTC Project Manager Cecil Joseph.
He adds: “We are working with the Advanced Biophotonics Laboratory to develop a multi-modal optical/terahertz imaging system to aid in the demarcation of cancer margins.”