Identification of chemical changes in healthy breast tissue caused by chemotherapy using Raman and FTIR spectroscopy: A preliminary study

Abstract

Chemotherapy is the most popular method for cancer treatment. However, it also damages healthy cells and causes other side effects that can lead to treatment failure. In this article, for the first time, we present the chemical changes, investigated by Raman spectroscopy and infrared oscillation spectroscopy (FTIR), found in healthy breast tissue after chemotherapy. The samples were collected from patients who were successful (Group I) and those who have been diagnosed with relapse or metastasis to other organs after chemotherapy (Group II). The obtained results indicated that larger chemical changes occurred in the samples from the second group, where structural changes in the amide I, II, lipids, and collagen were noticed, while in Group I, only changes in lipids were noticed. However, quantitative changes in the phenylalanine, glucose, lipids, proteins, including collagen and cholesterol, were observed in the breast tissue of both groups after chemotherapy. In contrast, the FTIR spectra indicated that regardless of the group, there were structural changes in the nucleic acids, amide I, and glycogen in the tissue after chemotherapy. In addition, for the tissue from the second group, structural changes in amide II, amide III, and cholesterol were observed. Interestingly, FTIR spectra after Kramers–Kronig transformation showed signals only for peaks originating from lipid vibrations, which changed the structure during carcinogenesis. The PCA analysis showed that the spectra of breast tissue before chemotherapy and after chemotherapy differed significantly in patients whose treatment was unsuccessful. The results indicate that the way the body copes with the chemical side effects of chemotherapy may affect the occurrence of a recurrence of the disease and that these changes can be examined by Raman and FTIR spectroscopy.