Blue Curing Light Therapy Stops HNSCC Tumor Growth In Vivo

Objectives: Head and neck squamous cell carcinoma (HNSCC) makes up 90% of all oropharyngeal cancers. The usual treatments for these tumors include chemotherapy, radiation and surgery; however, high associated morbidity and mortality rates persist. Few new therapies have been developed in the past 30 years; therefore, innovative and non-invasive treatments are desperately needed. Previous studies in our lab have shown that treatment of cultured HNSCC cells with 400-500 nm blue light (BL) delivered from a quartz-tungsten-halogen (QTH) curing light unit can significantly reduce their metabolic activity and/or cell numbers as measured by WST assay. This study expanded our work to determine whether these effects can be reproduced in an in vivo model.
Methods: UM-SCC-17B oral tumor cells were suspended in PBS (20 x 10⁶ cells/ml) and 100 μl were injected subcutaneously into the right abdomen of female nu/nu mice (n=8). Weights and tumor dimensions were recorded daily. At day 19 post-injection (average tumor volume ~50 mm³), the mice were separated into control (no treatment) and blue light treatment (45 J/cm²; 90 sec; Bisco VIP curing unit) groups. Mice were treated for 90 sec daily for 14 days. Then the tumors, livers, lungs and blood were harvested and either formalin-fixed for immunohistochemistry or flash-frozen in liquid nitrogen for western blot analysis.
Results: At the end of the treatment period, blue light-treated tumors were significantly smaller than untreated control tumors. Over the 14 day treatment period, control tumors grew from an average of 47 mm³ to 114 mm³ (143% increase), while blue light-treated tumors grew from an average of 51 mm³ to 56 mm³ (9.8% increase).
Conclusions: Blue light treatment essentially halted tumor growth and led to tumors that were significantly smaller in volume relative to control. Studies to compare molecular changes in the tumors are ongoing.