miércoles, 4 de diciembre de 2013

TARGETS LUNG CANCER WITH PROTONS: Proton Therapy for Lung Cancer

Pioneers in the Fight Against ‘the Big One’: Proton Therapy for Lung Cancer

Released: 11/12/2013 12:00 PM EST
Source Newsroom: University of Texas M. D. Anderson Cancer Center
Lung cancer is the number one cancer killer in the U.S., causing more deaths than the next three most common cancers – colon, breast and prostate – combined. Worldwide, lung cancer accounts for 1.3 million deaths annually. An estimated $10.3 billion per year is spent in the U.S. on lung cancer treatment alone, yet those diagnosed with the disease have just a 15 percent survival rate.1
Physicians at The University of Texas MD Anderson Proton Therapy Center are leaders in the research and treatment of lung cancer and pioneers in developing proton therapy for lung cancer patients. With its advanced image guidance and ability to precisely target tumors in the lungs, the powerful radiation of protons can be delivered with optimal accuracy – sparing critical nearby structures, such as the esophagus, heart and spinal cord. Because the tumor can be treated with a higher dose of radiation, benefits may include better local control of the disease, higher survival rates and improved quality of life.
“MD Anderson is at the forefront of the most advanced lung cancer treatments available. It is part of our mission to raise awareness of proton therapy as a potential option for people fighting for their lives,” says James D. Cox, M.D., former head of Radiation Oncology at MD Anderson. “When the Proton Therapy Center was established in 2006, for example, it was the first to treat lung cancer with protons and chemotherapy.”
Proton Therapy at MD Anderson
Roughly 15 to 20 percent of lung cancer patients have tumors that can be treated with surgery combined with other therapies such as radiation. Another 30 to 50 percent of patients have locally advanced tumors that require a combined treatment regimen that includes chemo or targeted therapy in addition to radiation therapy. However, it is challenging to deliver an adequate dose of radiation to a cancerous tumor while sparing nearby normal tissues.
Proton therapy’s advantage for many lung cancer patients is based on this feature. Further, by minimizing the exposure of normal tissues, proton treatment may also reduce some of the side effects of traditional radiation and help patients maintain good quality of life.

Proton therapy is currently available at only 11 centers in North America (13 centers are in development). MD Anderson has one of the largest and most technically advanced centers in the world. The 96,000-square foot Proton Therapy Center – the first proton center in the world within a comprehensive cancer center – offers a range of proton treatment options. These include pencil beam proton therapy, a highly precise form of proton radiation also known as scanning beam, and intensity-modulated proton therapy (IMPT) – the most advanced form of proton radiation. For patients with recurrent lung cancer, who have already received full doses of traditional radiation, pencil beam and intensity-modulated therapies may further limit or eliminate radiation to sensitive areas.
The Proton Therapy Center treats as many as 900 patients annually. Nearly 5,000 patients have been treated to date, accounting for 15 percent of the total number of patients who have received proton treatment nationally. Approximately 1,000 of these patients have been treated for lung cancer. The best lung cancer candidates for proton radiation are those whose cancer is localized in the chest and can’t be removed surgically, notes Cox.
“We’re just beginning to see the potential benefits of proton therapy and as we move forward it looks more and more like an excellent treatment modality,” says Anne S. Tsao, M.D., associate professor in Thoracic/Head and Neck Medical Oncology. “As we learn more and gather evidence of these benefits, proton therapy will likely be extended to a broader patient population.”
“We’re just beginning to see the potential benefits of proton therapy and as we move forward it looks more and more like an excellent treatment modality,” says Anne S. Tsao, M.D., associate professor in Thoracic/Head and Neck Medical Oncology. “As we learn more and gather evidence of these benefits, proton therapy will likely be extended to a broader patient population.”
Cox explains the outcomes of proton therapy with concurrent chemotherapy, how lung cancer patients typically tolerate treatment and what the future holds for lung cancer patients being treated with proton therapy at MD Anderson.
The Proton Therapy Center is advancing the science of proton therapy by providing answers to critical knowledge gaps, confirming the effectiveness of proton therapy and evaluating its use in combination with chemotherapy, targeted molecular therapies and conventional radiation therapy.
Every patient treated at the Proton Therapy Center is offered the opportunity to participate in one of more than 25 clinical protocols, which allow for the capture, analysis and reporting on treatment results related to tissue toxicity, dose optimization, and quality of life.
Lung cancer patients, for example, may take part in a phase II randomized clinical trial comparing high-dose traditional intensity-modulated radiation therapy (IMRT) with high-dose proton therapy. MD Anderson researchers are also investigating such areas as long-term outcomes for patients with locally advanced lung cancer treated with proton therapy and survival rates among proton lung patients versus those treated with traditional radiation and chemotherapy.

Since 2005, MD Anderson has published more than 175 studies focused on proton therapy for lung cancer. Recent findings include:
  • Concurrent chemoradiation therapy, the standard of care for locally advanced non-small-cell lung cancer (NSCLC), can cause esophagitis and pneumonia, and X-ray-based radiation often cannot be given at doses high enough to destroy tumor cells without toxicity to nearby normal tissues. In a study published in thejournal Cancer, researchers showed that higher doses of proton radiation can be delivered to lung tumors with lower risk of these life-threatening conditions.
  • Comparing toxicity and tumor coverage delivered to stage 1 NSCLC patients via traditional stereotactic body radiation therapy, passively scattered proton therapy and intensity-modulated proton therapy, researchers found that: the proton radiation approaches were better in terms of target volume coverage; significantly reduced the mean total lung dose; and reduced mean maximal dose to other nearby critical structures, including the aorta, heart, pulmonary vessels and spinal cord. The study was published in theInternational Journal of Radiation Oncology, Biology, Physics.
  • Proton Therapy Center researchers have completed phase I of a study, published in the International Journal of Radiation Oncology, Biology, Physics, examining the effect of shorter courses of proton beam therapy in patients that have locally advanced NSCLC but that cannot receive chemotherapy with radiation. Using higher doses of proton beam therapy, treatment was typically completed in approximately three weeks.

“Advances are rapidly occurring in the field of proton therapy for lung cancer. Consider the ability to precisely target a tumor that moves with every breath or radiating a recurrent cancer that previously we wouldn’t have because of the toxic effects of earlier treatments,” says Daniel Gomez, M.D., assistant professor in Radiation Oncology. “Evidence-based innovations in proton therapy are making it possible to treat complicated tumors that traditional forms of radiation can’t target as effectively. As more patients are treated, the technology will continue to improve.”
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