The study published on Monday in the journal Proceedings of the National Academy of Sciences reported that 13 of the 15 prostate cancer patients treated with the photothermal cancer therapy showed no detectable signs of cancer a year after treatment.

It is believed to be the first published clinical study of a nanoparticle-based, focal therapy that destroys tumors without the debilitating side effects of chemotherapy, invasive surgery and radiation.

Scientists from Rice University created tiny silica spheres with a thin outer layer of gold, which are called nanoshells and injected those particles about 50 times smaller than a red blood cell into the patients.

The particles are delivered into the peripheral blood system of the patient and they preferentially accumulate in the "leaky vasculature" of solid tumors due to the their size.

The particles essentially get caught or stuck in the gaps that characterize tumors, David Jorden, CEO of Nanospectra Biosciences, told Xinhua. Nanospectra is a Houston-based startup to develop the technology for clinical uses.

Then, the researchers heated the particles with a low-power, near-infrared laser that could pass harmlessly through healthy tissue.

In the study, 16 men aged 58 to 79 with low- to intermediate-risk localized prostate cancer received a focal ablation treatment that uses gold nanoparticles to heat and destroy tumors.

They underwent the two-day treatment at the Icahn School of Medicine at Mount Sinai, receiving an intravenous infusion of nanoparticles on day one and undergoing an image-guided ablation treatment on day two.

All of the patients went home on the day of the treatment and returned for follow-up tests at three months, six months and one year after treatment. Of the 15 who completed treatment, only two showed detectable signs of cancer in follow-up biopsies and Magnetic Resonance Imagings (MRIs) one year later, according to the study.

"Gold-silica nanoshell infusion allows for a focused therapy that treats the cancer while sparing the rest of the prostate, thus preserving a patient's quality of life by reducing unwanted side effects," said the clinical trial's principal investigator Ardeshir Rastinehad, associate professor of urology and radiology at the Icahn School of Medicine at Mount Sinai.

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