Proton Therapy Now Targets Lung Cancer -- Update

More than 160,000 Americans are expected to be diagnosed with lung cancer in 1999. That's more than breast, prostate, and colon-rectal cancer combined. Despite technical advances in surgery, x-ray radiation therapy and chemotherapy, long-term survival rates remain discouragingly low. This disease is the biggest cancer killer in America and in the world.

According to the American Cancer Society, over half of lung cancer patients can survive if their disease is treated before it spreads to other organs. The best results are obtained in patients whose tumors are small enough to be surgically removed. However, because of heart, lung and other medical problems, only about 20 percent of those patients can be treated with surgery.

That's why physicians at the Proton Treatment Center at Loma Linda University & Medical Center in southern California are keeping a close eye on a promising clinical study designed to treat such patients using proton therapy. The clinical study, begun in 1994, gives patients with early-stage , medically inoperative lung cancer an alternative to x-ray radiation therapy.

Protons Safer, Stronger Than X-ray Treatment

"Many of these patients are very sick," says Dr. David A. Bush, assistant professor of radiation medicine at Loma Linda University School of Medicine, and co-investigator of a Loma Linda University study published in the November issue of CHEST -a medical journal. "It is critical to minimize lung tissue damage, and protons allow us to do that," notes Dr. Bush.

Proton therapy offers a distinct advantage over x-ray radiation therapy in that it can deliver higher doses to a localized target area (cancerous tumors), and spare damage to surrounding tissue. Patients treated with proton therapy experience considerably less side effects than with other forms of treatment. Proton beams consist of particles of radiation, whereas x-rays are waves of radiation. With proton therapy, less radiation strikes normal tissue surrounding a tumor, decreasing the chance of damage to healthy organs and cells.

"The reason we chose to use a proton beam for these patients is that most had underlying lung disease that made them at risk for lung damage from regular x-ray radiation therapy. Because x-ray radiation is not concentrated or easily targeted, it can damage surrounding lung tissue, aggravating smoking-related problems such as emphysema. Most lung cancer patients are smokers or ex-smokers," Bush said. They are often bad candidates for surgery, which is why they must receive radiation treatment. X-ray therapy is the most common form of radiation treatment.

Loma Linda University researchers have so far studied nearly 40 early-stage lung cancer patients. To be eligible for the clinical research study, patients must have localized, early-stage lung cancer that can not be treated with surgery because of other related health problems. Also, the tumor must be limited to the lung, with no mediastinal lymph node involvement.

Currently, only a limited number of patients can be treated. However, current research is expected to enhance the expansion of lung cancer treatment protocols with protons, as well as adding breast cancer in the near future to the growing list of tumor sites treated with proton therapy.

According to Dr. Bush, preliminary results of the lung study are encouraging. The disease-free survival rate at 2 years for stage 1 patients was 86 percent.

Dr. Bush estimates that approximately 5,000 Americans per year are diagnosed with early-stage, medically inoperable lung cancer. If early indications are accurate, proton therapy may become an important tool, and likely a preferred option, in the treatment of these patients. Physicians at Loma Linda University & Medical Center have treated approximately 5000 cancer patients from all over the world since it opened the world's first hospital-based proton center in 1990. Current protocols include over 20 different cancer sites; over half of the LLUMC patients are treated for prostate cancer, where the cure rate is equal or better when compared to surgery, radiation or other treatments, plus protons have the advantage of significantly fewer side affects.

More information about proton therapy is available by calling 1-800-PROTONS (1-800-776-8667), or visit .

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