The lack of quick and dependable screening tools for melanoma and lymphoma is unfortunate for at least two reasons. First, early diagnosis of these conditions improves survival rates. And second, the incidence of cutaneous melanoma is increasing in many regions and populations, while non-Hodgkin lymphoma (NHL) remains one of the most common cancers in the U.S. But because the current diagnostic is time-consuming, invasive, and costly, eligible populations often opt out of testing.
Now, a research team at Georgia State University (Atlanta, GA) has discovered that Fourier-transform infrared (FTIR) spectroscopy in attenuated total reflection (ATR) sampling mode has diagnostic potential as a rapid, reliable, and minimally invasive screening technique. The approach, the researchers found, provides high-quality results with improved reproducibility compared to other vibrational spectroscopies.
The team used mid-IR (a spectral region often used to characterize biological samples at the molecular level) spectroscopy to analyze blood serum from mice. The findings suggest that IR spectroscopy works by detecting cancer-induced biochemical changes: The approach proved able to distinguish cancerous and healthy tissues, and even to differentiate mice with NHL (a solid tumorous condition of the immune system) from those with subcutaneous melanoma (a deadly form of skin cancer).
FTIR spectroscopy in ATR sampling mode has proven able to detect various health conditions using body-fluid samples.1 For instance, Unil Perera, a physics professor who headed the research, previously led a team that discovered a fast, simple ATR-FTIR spectroscopy-based blood test (see figure) that could serve as a less-expensive and less-invasive option to colonoscopy for screening ulcerative colitis.
For their experiments, the researchers used an FTIR spectrometer fitted with an ATR accessory. The researchers placed blood serum droplets—extracted from cancerous mice and controls—on the 1 × 1.5 mm diamond crystal, which served as an internal reflection element and was configured for a single reflection of IR radiation. Each serum specimen absorbed and reflected incident IR beams, creating an evanescent wave with penetration of about 2.5 μm.
In each case, the researchers recorded the wave and used it to produce an absorbance curve, with peaks identifying the presence of key biomarkers. They then compared the absorbance curves from the control and tumorous mice, and assessed biochemical changes induced by the two cancers. The study found remarkable differences between the ATR-FTIR spectra of serum samples from tumor-bearing mice and healthy controls.
The researchers' data laid a foundation for further research that could enable development of detectors for these particular absorbance peaks, as well as diagnostic techniques using body fluid samples that can be collected at relatively low risk. The findings are applicable to humans because we share critical biomarkers and chemicals with mice, Perera says. In fact, Perera and his colleagues hope next to use samples from human patients for IR spectroscopy studies of cancer and other diseases.
The team's ultimate goal is to use IR light to screen for a variety of diseases. "Right now, when you go to the doctor, they do blood tests for sugar and several other things, but not for serious diseases like cancer and colitis," Perera explains. "One day, we hope that even these serious diseases can be rapidly screened [on a routine basis]." Then, as with weight and blood pressure, primary care providers (PCPs) could track their patients' blood-test results from infancy. Statistical analysis software could make before and after comparisons, determine any significant differences, and alert the PCP to take action when readings exceed normal ranges.
1. H. Ghimire et al., Sci. Rep., 7, 16993 (2017).