Method for diagnosing neoplastic lesions by quantitative fluorescence value (original) (raw)

Fluorescence visualization devices (FVs) are useful for detecting malignant lesions because of their simple and noninvasive application. However, their quantitative application has been challenging. This study aimed to quantitatively and statistically evaluate the change in fluorescence intensity (FI) during the progression from normal epithelium to squamous cell carcinoma using a reproducible animal tongue carcinogenesis model. To establish this model, rats were treated with 50 ppm 4-Nitroquinoline 1-oxide (4NQO) in their drinking water for 10, 15, and 20 weeks. After 4NQO administration, each rat tongue was evaluated by gross observation, histology, and FI measurements. Fluorescence images were captured by FV, and ImageJ was used to measure FI, which was analyzed quantitatively and statistically. The establishment of a reproducible tumor progression model was confirmed, showing precancerous lesions (low-grade dysplasia [LGD]), early cancers (high-grade dysplasia/carcinoma in situ [HGD/CIS]), and advanced cancers (Cancer). This carcinogenesis model was quantitatively evaluated by FI. The FI of LGD stage was 54.6, which was highest intensity of all groups. Subsequently, the HGD/ CIS and Cancer stages showed decreased FI (HGD/CIS: 46.1, Cancer: 49.1) and manifested as dark spots. This result indicates that FI had more variation and a wider range with increasing tumor progression. We demonstrated that FI migration and an uneven distribution are consistent with tumor progression. Since each step of tumor progression occurs reproducibly in this animal model, statistical evaluation was possible. In addition, tumor progression can be monitored by this new FI analysis method in humans. The morbidity of oral cancer has increased over the past few decades. While treatment methods are improving, survival rates remain low, largely because it is hard to distinguish oral mucosal lesions, such as oral potentially malignant disorders (OPMDs), from early stage cancer. Although the oral cavity can be diagnosed via direct viewing, the early detection of oral premalignant or cancerous lesions remains difficult 1. The grade of dysplasia is not easy to differentiate by general pathologists. If these lesions have to be monitored over time, the use of non-invasive methods rather than repeated biopsies will benefit patients. Therefore, noninvasive methods are preferable for diagnosing these lesions at an early stage. Recently, it has been demonstrated that fluorescence visualization devices (FVs) are useful for detecting lesions of the oral mucosa, and especially to discriminate between OPMDs such as oral lichen planus, leukoplakia, and dysplasia 2-6. Among its benefits, the FV system is simple and noninvasive to use 7,8. The IllumiScan ® FV (Shofu Inc, Kyoto, Japan) uses 425 nm wavelength visual light to distinguish between normal and abnormal mucosa 9-11. Normal oral mucosa has a fluorescence spectral range of approximately 375 nm to 440 nm. Under this light, normal mucosa emits pale green fluorescence while abnormal areas absorb the fluorescent light, resulting in dark patches with fluorescence visualization loss (FVL) 12,13. However, it has not yet been determined why abnormal parts of the mucosa cause FVL. It has been shown that FV can detect differences in fluorescence between normal mucosa and epithelial dysplasia 1,3,14. Other reports have demonstrated that FV can be used as a diagnostic tool of for oral malignant disorders, but such observations have not been evaluated quantitatively 15. This lack of quantification may be a result of human oral cancer being caused by many factors, including smoking, alcohol consumption, and viral infection. Moreover, different parts of the oral cavity mucosa vary in the degree