Raman spectroscopy of serum: an exploratory study for detection of oral cancers

Abstract

Early diagnosis of oral cancers, one of the major cancers, is of utmost importance as 5-year disease-free survival rates are some of the lowest, despite advances in treatment and surgical modalities. In vivo Raman spectroscopy has shown efficacy in the detection of normal, premalignant and malignant lesions and even of early changes such as cancer-field-effects/malignancy-associated-changes. However, the need for a dedicated instrument and stringent laboratory conditions, at all diagnostic centers, limits wide screening applications of this method. In light of this, it is pertinent to explore ex vivo samples like serum due to its ease of collection, storage, transport and analysis at a centralized facility. Hence, Raman studies were carried out on serum from 14 buccal mucosa and 40 tongue cancers as well as 16 healthy control samples. Spectral features indicate differential contributions of proteins, DNA, and amino acids like Phe, Trp and Tyr and β-carotene in the analyzed groups. Highly intense Raman bands assigned to β-carotene could be due to resonance Raman, and were observed in all sera with the highest relative intensity in normal samples. Higher DNA and protein content were observed in the mean cancer spectra. Principal component-linear discriminant analysis (PC-LDA) followed by cross-validation using leave-one-out cross-validation (LOOCV) were employed for data analysis which was carried out both spectra- and patient-wise. Findings indicate the possibility of classifying normal and oral cancer sera in both these approaches; however, the patient-wise approach could be the preferred mode for prospective studies. Besides, a tendency of classification for buccal mucosa and tongue cancers was also observed. Prospective validation of these results on a large sample size may help in the translation of this methodology to clinics.

Improved protocols for vibrational spectroscopic analysis of body fluids

“…[62,[67][68][69] and limitations due to the presence of water are often quoted in recently published materials [70]. Therefore, in the present study, different approaches will be described and proposed as alternatives in order to demonstrate and highlight the feasibility to record high quality data without the requirement for water free samples.…”

Ultra-filtration of human serum for improved quantitative analysis of low molecular weight biomarkers using ATR-IR spectroscopy

“…This further supports the increased clinical relevancy of the quantitative measurement performed after isolation of the LMW fraction." Recently, an increasing numbers of publications promote the capabilities of IR and Raman spectroscopy for serum analysis in both animal and human models from cardiovascular disease to cancers diagnosis [60][61][62] . However even facing the difficulties to accurately perform specific discrimination or diagnosis 2,52 , resorting to pre-analytical sample preparation procedures is rarely or never considered.…”

Raman Spectroscopy of Blood and Blood Components

“…They observed differences in the bands associated with nucleic acids (the differences suggested an increased cell-free DNA presence) and a decrease in the amount of b-carotene for patients in the cancer group. 172 In 2015, they repeated the study using a larger subject cohort (328 donors, 785 nm excitation) and an added dimension of evaluating the serum for the detection of premalignant chemical conditions. 173 Another 2015 study from the group investigated the feasibility of discriminating between serum from patients suffering from malignant tumors who had endured a recurrence of their cancer post-surgery and serum from patients suffering from malignant tumors who had not.…”