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High Dose Radiation(HDR)

If you've already had external beam radiation therapy, you understand the benefits of radiation in fighting tumorts, and are familiar with the procedures that accompany treatment. However, HDR differs from these traditional radiation treatments in several ways.

External beam radiation is given from outside the body, using a high-energy linear accelerator. HDR on the other hand, is a form of brachytherapy, meaning that the threament is delievered within the site of the disease. Because the placememnt is so precise and the lenht of each treatment is so short, very high doses of radiation can be given.

This is a high technology cancer treatment that places doess of radiation dirtectly into malignant tumors.

Thin tubes, called catheters are precisely inserted into the cancer site by physicians and medical staff. Then a specific dosage of radioactive material is loaded into the tubes left in place for the prescribed treatment period and retracted. This after-loading is controlled remotely by sophisticated computerized equipment.

The proceedure is often part of a treatment plan that may include surgery, chemotherapy, or more familiar external bean radiation. HDR is effective in treating cancer of the lung, esophagus, uterus, cervix, breast, and prostate, among others.Depending on the type of cancer and the progress of the disease, HDR therapy can destroy tumors, arrest or control their growth, or offer relief from pain.
(source - Greater Harrisburg Cancer Center)

HDR in the Instance of Mesothelioma

Mesothelioma, a rare but extremely lethal type of lung cancer affecting the lining of the lung, has always been a challenge to treat. A new study finds that extensive surgery (removal of the lung and the lining of the lung) followed by high dose radiation therapy is well tolerated, and may improve local disease control and survival rates.

About 2,200 cases of mesothelioma are diagnosed per year, the majority of which are caused by environmental exposure to asbestos.

"For many years we were unable to give too much radiation to the chest because of extreme toxicity, but new technologies and treatment techniques have helped us get around that," said Santosh Yajnik, MD, radiation oncologist at MSKCC and lead author of the study. One of the reasons doctors were able to give higher doses of radiation therapy to patients in this study was because the affected lung had been completely removed.

In the last four years, MSKCC has seen about 365 patients with mesothelioma, and approximately 63 patients were treated with this type of extensive surgery. This experience makes the Center one of only a handful of hospitals in the country with expertise in this area.

In this study, 32 patients with various stages of mesothelioma who had surgery at MSKCC between 1990 and 2000 were treated with high dose radiation therapy. The median overall survival was 17 months compared to median survival rates of about 12 months historically seen in patients who have surgery alone. Researchers noted that patients with earlier stage disease experienced better survival rates than those with late stage cancer. They also observed that patients tolerated the treatment well without suffering high levels of toxicity.

Four patients had local tumor recurrence, seven had local and distant recurrence, and nine patients had distant disease recurrence. "Now that we know radiation helps with local control, the next step is to study whether chemotherapy can further reduce mortality rates and improve distant control of the tumor," concluded Dr. Yajnik.

(source- Memorial Sloan-Kettering Cancer Center at the American Society for Therapeutic Radiation and Oncology (ASTRO) annual meeting in November, 2001)

Addtional Information:

http://www.cooleyville.com/cancer/cahdrst.htm

HDR in the Instance of Prostate Cancer

Patients with clinically localized prostate cancer have a better chance of beating the disease with higher doses of radiation, which can be safely and precisely delivered to the tumor with few side effects using three-dimensional conformal radiation therapy. While dose escalation has been shown to improve patient prognosis across all disease stages and risk groups, doctors at Memorial Sloan-Kettering Cancer Center have been able to substantiate the success of the treatment using biopsy results.

In a biopsy, several needles are inserted into the prostate to withdraw cells, which are then examined under a microscope. According to preliminary findings from a study being presented at the American Society for Therapeutic Radiology and Oncology (ASTRO) meeting in Boston this week, prostate cancer patients who received higher doses of radiation therapy were more likely to have a negative biopsy, indicating the disease had been controlled or cured. Tumors that received lower doses of radiation were less likely to be eliminated.

The lower doses delivered in the study were the standard prescription for radiation therapy when it began in 1989. As three-dimensional technology proved to be the most precise method to deliver radiation, doctors slowly escalated the dose levels when appropriate. This study used biopsy as a barometer to determine whether dose escalation eliminated the disease in the prostate three years after treatment.

Doctors have traditionally monitored levels of Prostate Specific Antigen (PSA) to test the effectiveness of radiation therapy after prostate cancer patients have completed treatment. However, a rise in a patient’s PSA level does not always reveal whether the cancer-cell activity detected is in the prostate or somewhere else in the body.

“Biopsy provides very accurate information about local disease specifically in the prostate gland, whereas PSA level gives a more general picture,” said Michael Zelefsky, MD, a radiation oncologist with expertise in the treatment of prostate cancer at Memorial Sloan-Kettering Cancer Center and lead author of the study.

The research found that lower radiation dose was the strongest predictor of a positive biopsy, indicating the prostate cancer had not been eliminated. The findings also suggest that higher radiation dose was critical in eradicating the disease, even among patients with aggressive prostate cancers – those patients with high Gleason scores in whom cancer cells are more resistant to radiation and more likely to spread to other areas of the body.

In the study, which was conducted between 1989 and 1998, 1,100 patients were treated with varying doses of three-dimensional conformal radiation therapy for clinically localized cancer that had not spread beyond the prostate. Three years after treatment, 63 percent of eligible patients received a prostate biopsy. The incidence of positive biopsy was 54 percent among patients who had the lowest radiation dose in the study, compared with only 10 percent among those who had the highest dose. Overall, the vast majority of patients whose biopsy indicated their cancer was controlled or cured were cancer-free and had normal PSA levels five years after treatment.

“The improved biopsy and PSA results support the effectiveness of higher doses of radiation therapy, which translates into a better chance of eliminating the disease in the prostate,” said Steven Leibel, MD, chairman of Radiation Oncology at Memorial Sloan-Kettering and senior author of the study.

The use of hormone therapy with radiation treatment was also shown to be a strong predictor of biopsy outcome. Of the 252 patients evaluated in the study, 33 percent were treated with three months of hormone therapy to shrink the size of the tumor prior to radiation treatment. The findings show that patients who were treated with hormone therapy and three-dimensional conformal radiation therapy were less likely to have a positive biopsy compared to patients treated with radiation therapy alone.

According to the American Cancer Society, 179,000 men in the US will be diagnosed with prostate cancer this year, and 37,000 will die of the disease. It is the second leading cause of cancer deaths (after lung cancer) among American men.