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CHICAGO -- Treating people with stereotactic body radiation for suspected -- but unbiopsied -- lung cancers appears to allow for acceptable local control of the disease with low toxicity, researchers reported here.

"We achieved crude local control of lung cancer in 97.1% of our patients," said , MD, assistant professor of radiation oncology at the Loyola University Chicago Stritch School of Medicine, in his oral presentation.

"The estimated 2-year regional control is 80%; distant control is 85%, and overall survival is 85% in 16.7 months of median follow-up," Harkenrider said at the annual meeting of the Radiological Society of North America. The RSNA meeting is the largest medical meeting in the U.S., with an expected attendance of more than 50,000 doctors, radiologists and allied healthcare professionals.

"About 15% of non-small-cell lung cancer is localized to the lung at diagnosis and can be controlled by sublobar dissection," he explained. "However, when sublobar dissection can't be performed without wedge dissection or segmentectomy, the local control is inferior to lobectomy."

"Lung cancer patients also have chronic obstructive lung disease, vascular disease and other comorbidities that preclude surgical management. In these cases, stereotactic body radiation therapy has been used as the preferred treatment management for these patients. Some patients have radiological evidence of tumors but cannot tolerate the biopsy procedure; others have undergone unsuccessful biopsy," he said.

The goal of the study was to investigate outcomes among this population, Harkenrider said.

The work was done at the University of Virginia and at the University of Louisville -- where Harkenrider performed his residency -- during the period from 2007 to 2011. The study retrospectively analyzed patients treated with stereotactic body radiation therapy without confirmatory biopsy. None of the patients had nodal disease and there was no evidence of metastases at baseline. However, they did have radiographic imaging consistent with lung cancer.

The researchers enrolled 34 patients who fit the criteria -- 17 from each of the participating institutions. They underwent pretreatment imaging with CT and PET/CT scans. They were treated with a median radiation dose of 50 Gy, in a median of 5 fractions. All patients underwent additional CT scans 6 to 8 weeks after the initial stereotactic body radiation procedure, and then every 3 to 6 months thereafter.

Median age of the patients in the study was 76 years; the patients had an Eastern Cooperative Oncology Group Performance Status of 0-1; most patients exhibited a degraded lung performance. Nineteen of the 34 patients did not have a biopsy due to their chronic obstructive lung disease or pneumothorax; another eight patients had cardiac disease that ruled out the stress of performing a biopsy, Harkenrider said.

He said that acute toxicity of the radiation therapy was well-tolerated by the patient population. No grade 3 or greater toxicities were observed, he said. Three late grade 3 dyspneas were treated.

"We had only one local failure in these patients," Harkenrider said. "The majority of the patients had stable lesions on follow-up." He added that most patients do not achieve a complete response with stereotactic body radiation therapy.

Session moderator , MD, of the University of Texas MD Anderson Cancer Center in Houston, told 木瓜直播, "This concern of whether we are really treating cancer can always occur when there is no biopsy. But we have imaging follow-ups in these patients. We see these lesions enlarge. We feel quite comfortable in treating these cases. We are actually treating more and more of those tumors in these cases."

The concern over whether patients actually do have cancer "also depends upon what area of the country you are treating patients," Harkenrider told 木瓜直播. "In the South, where most of these patients lived, there is endemic granulomatous lung disease," which can mimic lung cancer nodules on scans. However, he noted, this study's results are in line with findings in areas where there are populations without the concern for granulomatous lung disease

"To our knowledge, this is the first U.S. series to solely report outcomes for these patients," he said. "Standard of care for medically inoperable, early stage lung cancer patients remains to obtain pathologic diagnosis prior to treatment."

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