Benefits for diagnosis

In the fight against cancer, winning half the battle is based on early detection. Nanotechnology is contributing new molecular agents and methods to enable earlier and more accurate diagnoses and treatment monitoring.

Imaging

Current imaging methods can detect cancers only once they have made visible changes to a tissue. This often takes many years: by this time thousands of cells have proliferated and perhaps metastasized. Even when visible, the nature of a tumor-malignant or benign-and the characteristics that might make it responsive to a particular treatment must be assessed through often invasive biopsies.

Imagine instead if cancerous or even precancerous cells could somehow be tagged for detection by conventional scanning devices. Two things would be necessary:

• Something that specifically identifies a cancerous cell and
• Something that enables it to be seen

Both can be achieved through nanotechnology. For example, antibodies that identify specific receptors found to be over-expressed in cancerous cells can be coated on to nanoparticles that then produce a high contrast signal when Magnetic Resonance Images (MRI) or Computed Tomography (CT) scans are used.

		Thus nanotechnology can enable the visualization of molecular markers that identify specific stages and types of cancers, allowing doctors to see cells and molecules undetectable through conventional imaging.
Image of a cancer cell illuminated by gold nanorods bound to anti-EGFR. Image courtesy of Mostafa El- Sayed, Georgia Tech

 

Examples of nanotechnology imaging in cancer diagnosis

• Nanoparticles can enhance the efficacy of magnetic resonance imaging (MRI) in detecting the spread of cancer.
  • In clinical trials, lymphotropic iron oxide nanoparticles acted as effective contrast agents and allowed the detection of small nodal metastases in men with prostate cancer that would otherwise have been overlooked.
  • Nanoparticulate iron oxide particles were used with MRI to accurately detect metastatic lesions in lymph nodes without surgery.
• Nanoparticle contrast agents for ultrasound have also been developed that can enhance the sensitive detection of vascular and cardiac thrombi, as well as solid tumors of the colon, liver and breast, in a noninvasive manner.

Biomarker Screening

Diagnostic screening for biomarkers in tissues and fluids could also be enhanced and potentially revolutionized by nanotechnology. Individual cancers differ from each other and from normal cells by changes in the expression and distribution of tens to hundreds of molecules.

As therapeutics advance, it may require the simultaneous detection of several biomarkers may be required to identify a cancer for treatment selection. Nanoscale cantilevers and nanowire sensors can detect biomarkers of cancer from a single cell.

Nanoparticles such as quantum dots, which emit light of different colors depending on their size, could enable the simultaneous detection of multiple markers.

		In this illustration, quantum dots are depicted as gold spheres that attract damaged DNA strands that are linked to cancer. When the quantum dots are exposed to certain types of light, they transfer the energy to fluorescent molecules, shown as pink globes that emit a glow. This enables researchers to detect and count the DNA strands linked to cancer. The downside, however, is that quantum dots are usually made of quite toxic elements.
Image courtesy of Dr. Yi Zhang/JHU