De Felice C et al. (2006) Abnormal oral mucosal light reflectance: a new clinical marker of high risk for colorectal cancer. Gut 55: 1436–1439

It is well established that the radiation reflected or emitted by an object gives useful information about its composition. This method, however, has not often been used for diagnostic purposes. De Felice and colleagues have investigated the capacity of oral-mucosal light reflectance to identify individuals at risk of developing hereditary nonpolyposis colorectal cancer (HNPCC); they had previously noted vascular aberrations in the oral mucosa of a family known to have gene mutations that cause HNPCC.

The study comprised 20 members of 6 unrelated HNPCC families and 30 age-matched and sex-matched healthy controls. An imaging spectrometer was used to measure the reflectance of participants' lower gingival and vestibular oral mucosa. Compared with controls, carriers of genetic mutations that cause HNPCC had significantly lower mucosal reflectance values in the longer wavelengths of the visible light spectrum (P ≤0.0004). A cut-off of ≤47.9% at the 700 nm wavelength discriminated between controls and carriers of HNPCC mutations with 100% sensitivity and specificity.

Early identification of those at high risk for colorectal cancer has been shown to reduce their risk of cancer occurrence and mortality. Genetic testing is currently a common means of identifying at-risk families and individuals; if these results are validated in further studies, this method might be a simpler and more cost-effective means of identifying carriers of HNPCC mutations.