On August 10, 2012, Steven Fiering et al. at the Dartmouth Geisel School of Medicine published their findings regarding innovative treatments for peritoneal cancers.
Cancer that has not yet undergone metastasis is commonly treated with radiation or surgery. As the stages of cancer progress, tumor cells spread and cannot be removed by surgery or treated with radiation therapy. Chemotherapy is generally applied from this point on, but it cannot accurately target specific tumor cells and destroys normal cells in the process. The discovery of possible treatments based on nanotechnology and hyperthermia will be able to target tumor cells with increased precision. Rather than using radiation like chemotherapy, the treatment would use heat generated from a magnetic field to destroy cancer cells.
Nanotechnology is a growing field in cancer treatment. The process involves implanting metal nanoparticles into the cancer patient and applying a magnetic field at the correct frequency to incite heat to kill abnormal cells. Ovarian cancer, a type of peritoneal cancer, has been treated effectively with intravaneous (IV) administration of nanoparticles. However, this method of injecting nanoparticles into the body presents enormous obstacles in directing where the particles should concentrate. Nanoparticles are more likely to be absorbed into liver cells than to tumor locations. Intraperitoneal (IP) injection, although more controversial, can send nanoparticles directly to the peritoneal region, which could improve the efficiency of nanotechnology in cancer treatments.
The researchers found specific tumor-associated immunosuppressive phagocytes that are continually recruited to tumor sites. Using these phagocytes, the researchers injected iron oxide nanoparticles (IONPs) into mice affected with cancer cells. Nanoparticles were covered with starch to induce phagocytes to engulf IONPs. They found a difference in the uptake of IONPs covered in various types of mediums by tumor cells in vitro, but not in vivo. The researchers then concluded that IONPs are not taken up directly by tumor cells but rather, are carried to tumor tissues by phagocytes. This was confirmed by the observation that iron particles were embedded deep into cells rather than simply adhering to cell surfaces.
After the IONPs were located at the tumor site, an alternating magnetic field (AMF) was applied to the nanoparticles. This process generates heat (hyperthermia) to treat cancer. Increased temperature was observed to cause damage to tumor cells.
Since the iron particles have low toxicity and were centralized in the tumor area, there were no significant side effects. In addition to inducing tumor cell death, hyperthermia also activates heat shock proteins (HSPs) that increase the antitumor immune response.
This new discovery of phagocyte- mediated targeting of nanoparticles to tumor cells overcomes the traditional obstacle of specifically targeting tumor cells. AMF could be applied to iron oxide nanoparticles that respond to magnetic fields to suppress tumors. As technology improves, the combination of nanotechnology and other cancer therapies will improve overall treatment of peritoneal and ovarian cancer.