Background: Colorectal Cancer is the third most commonly diagnosed cancer in males and the second in females in world with continuously increased incidence and mortality. The main treatment for Colorectal Cancer is surgery, generally associated with chemotherapy, and radiation therapy. 
Objectives: A prospective study was conducted to primarily investigate the anticancer properties of synthesized cadmium sulfide nanoparticles with three different complex agents on Caco-2 epithelial colon adenocarcinoma. The study also involved comparing the efficacy of nanoparticles versus radiation therapy.
Materials and Methods: Nanoparticles were produced using a wet chemical process and characterized for their physical and chemical properties using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, and optical property analysis. The research involved exposing cancerous colon Caco-2 cells to different concentrations of CdS1-NPs, CdS2-NPs, and CdS3-NPs, and combining the nanoparticles with radiation therapy. The cells were treated with three doses over a span of three days, each dose consisting of 80 CGy delivered using an Elekta Precise Linear Accelerator with photons energy at 6 mega volts.
Results:   The cadmium sulfide (three different complex agents) are crystallite size (9 -12.59) nm, and energy gap (3.31- 3.86) eV. When used nanoparticles alone CdS1-NPs, CdS2-NPs, and CdS3-NPs killed about 75%, 71%, 79% of cells respectively. But when used nanoparticles and radiation. {Radiotherapy alone, ((CdS1 – NPs, CdS2- NPs, and CdS3-NPs) with radiotherapy)} the death rate of cells is (27.15 %, 90.35%, 69.1%, 58.82%) respectively, as after the third dose.
Conclusion: The current investigation demonstrated that combining nanoparticles with radiotherapy resulted in a more significant effect compared to radiotherapy alone.