NEWS

ASTRO Plenary Session Touts Top New Research

Nancy Volkers

High-dose radiation is a catch-22 in cancer treatment: It's effective at killing cancer cells but extremely dangerous to normal tissues. Recent research shows that in certain men with prostate cancer, the benefits seem to exceed the costs.

According to Alan Pollack, M.D., Ph.D., of the University of Texas M. D. Anderson Cancer Center, Houston, prostate cancer patients whose pretreatment prostate-specific antigen levels are above 10 have less recurrence and fewer distant metastases when treated with high-dose radiation, compared with standard doses of radiation therapy. Pollack, an associate professor of radiotherapy, presented the results of a randomized clinical trial at the recent annual meeting of the American Society for Therapeutic Radiology and Oncology in San Antonio, Texas.Go



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In the trial, 149 patients were randomized to a standard radiation dose of 70 Gy while 151 patients were given a higher dose of 78 Gy. After 5 years of treatment, 75% of the high-dose radiation group did not have rising PSA levels, compared with 48% of patients who received a standard radiation dose.

"A rising PSA profile is the most sensitive indicator that cancer has returned," contended Pollack. An additional benefit: the 5-year rate of distant metastasis was 2% for the high-dose radiation group, compared with 13% for patients receiving the standard radiation dose.

"There is sufficient evidence," Pollack said, "to support the implementation of dose escalation to modest levels in clinical practice for prostate cancer patients with intermediate- to high-risk features." The patients will continue to be followed, he said.

Hormone Edge

Also at ASTRO, results of an 8-year European trial looking at adjuvant hormone therapy for prostate cancer were presented. Twenty-six institutions participated in the trial, run by the European Organization for the Research and Treatment of Cancer. The study found that adding goserelin (Zoladex) — a leutinizing hormone-releasing hormone agonist — to radiation therapy is superior to radiation alone for the treatment of this cancer.

A total of 415 patients were enrolled in two arms: one group of patients received radiation therapy and the other received radiation plus goserelin, which was given intravenously once a month for 3 years.

Michel Bolla, M.D., Centre Hospitalo-Universitaire Albert Michallon, Grenoble, France, said that adjuvant therapy with goserelin proved superior to radiation therapy alone by a number of measures: patient deaths were fewer in the combined therapy group (43 vs. 12), disease progression was less apparent (90 vs. 27), and patients on combined therapy had fewer distant metastases (56 vs. 22).

Most patients in the EORTC trial were 70 years or older and 82% in each arm had locally advanced disease. More than 30% of men in each group had PSA levels greater than 10. More than 65% of the patients in the goserelin arm received the full 3 years of therapy. Long-term side effects in both groups were quite rare; the most common side effect was hot flashes in the goserelin-treated group.

Goserelin is indicated for the palliative treatment of advanced prostate cancer, and for the management of locally confined prostate cancer. It is currently in clinical trials in the United States for other prostate cancer indications, as well as for breast cancer.

While adjuvant therapy may be effective for prostate cancer, it is not effective in node-positive non-small cell lung cancer. Henry Wagner Jr., M.D., presented the results of an Eastern Cooperative Oncology Group trial that compared radiation therapy alone to radiation plus cisplatin and etoposide in NSCLC patients whose primary tumors had been resected.

Wagner, an associate professor of radiology at the University of South Florida, said that the addition of chemotherapy did not improve survival, relapse-free survival, or local control.

Patients treated with radiation therapy alone had a median survival of 42 months, compared with 38.6 months in those also receiving chemotherapy; the difference was not statistically significant. After 40 months, 52% of patients receiving only radiation, and 51% of those receiving chemotherapy, had relapsed.

"There is a need for effective chemotherapy," said Wagner, "but we don't know at this time what type of drugs and what treatment schedule are most effective."

Part of the difficulty, he said, is that only about 3% of NSCLC patients enter clinical trials each year, though between 20,000 and 30,000 cases of node-positive NSCLC are diagnosed.

Karen Fu, M.D., professor of radiation oncology, University of California, San Francisco, presented results of a Radiation Therapy Oncology Group study of changes in radiation treatment for head and neck malignancies. Study data showed that a net increase in dose per unit time — achieved either by increasing the radiation dose without changing the total treatment time, or by reducing the treatment time without changing the dose — was an improvement over standard treatment.

The local tumor control rate at 2 years for standard treatment is 46%. Patients receiving an increased dose over the same time had a control rate of 54.4%; those receiving the same total dose over less time had a control rate of 54.5%. The RTOG study included more than 1,000 patients.



             
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