The Structure of Nanocrystalline Apatite from the Non-Small Cell Lung Cancer

This study focuses on the physicochemical composition of calcifications in non-small cell lung cancer (NSCLC). Among all histological forms of NSCLC within the studied group, calcifications were observed only in two types: basaloid squamous cell carcinoma and mucinous lung adenocarcinoma. Transmission electron microscopy (TEM) revealed that the calcification samples from NSCLC exhibited a crystalline structure with a broad range of crystal sizes (from 7 to 300 nm), with the most common sizes ranging from 7 to 14 nm. X-ray microanalysis and elemental distribution mapping indicated that, for both squamous cell carcinoma and lung adenocarcinoma samples, the mineral deposits were composed of calcium phosphate (apatite), as suggested by the $\mathrm{Ca} / \mathrm{P}$ ratio. Distribution maps also showed a significant oxygen presence at calcification sites, associated with the phosphate group of apatite $\left(\mathrm{PO}_{4}\right)$. Despite the identical chemical composition of the calcifications in NSCLC, differences in the shape and localization of these biomineral deposits can help distinguish between different histological cancer types and serve as potential markers for disease prognosis.