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U.Va. DOCTORS DEVELOP TECHNIQUE TO LOCATE TINY LESIONS IN THE LUNG

Imagine using a medical “geiger counter” to locate pre-cancerous or cancerous lesions in the lungs. A multidisciplinary team of physicians at the University of Virginia Health System, led by thoracic surgeon  Dr. Thomas Daniel, has done just that by developing a radioactive technique to find small or ill-defined pulmonary nodules that can then be removed by video surgery.

The technique, published in the May 2004 issue of  “The Annals of Thoracic Surgery,” uses a radiotracer substance called macroaggregated albumin (MAA) that is placed by radiologists using a CT scan in or near a suspicious lung nodule the morning of surgery. After the patient is put to sleep, surgeons use a sterile radioprobe to guide them to the small or diffuse lesion, which is then removed.  Previous animal studies at U.Va. revealed that MAA, used with a source of gamma radioactivity called technetium-99, stays in the area of the lung lesion for many hours after being inserted by a tiny needle between the ribs and can guide a gamma probe to locate the lesion later on in surgery. The small amount of gamma radiation used is extremely safe for patients, according to physicians.

The findings could be important in detecting lung cancer at an early stage, potentially leading to longer survival for patients, especially long-term smokers. Researchers in Italy and Japan have previously used different radiotracers that are not available in the U.S. to localize lung nodules.

Cancer of the lung and bronchus is still the most common and deadliest form of cancer today, leading to an estimated 157,200 deaths in the U.S. in 2003, according to the American Cancer Society. Though the one-year survival rate for patients diagnosed with lung cancer increased to 42 percent in 1998, five-year survival for all stages of the disease is only 15 percent and has not changed drastically in twenty years. Survival increases, however, to 70 percent when lung cancer is caught early and the disease is localized to lung tissue and has not spread to adjacent lymph nodes.

“For all our CAT scans, chemotherapy and good surgical techniques, the long-term survival rate for lung cancer patients is essentially where it was in the 1970s and 80s,” said Daniel, a professor of surgery at U.Va. who co-edited one of the first textbooks on video lung surgery fifteen years ago. “There’s nothing like a prostate-specific antigen (PSA) test for lung cancer patients. There’s no blood study for lung cancer. So, the more precise we are at locating and taking out small lesions in the lung, the more patients will experience lower mortality rates and fewer post-operative complications. The objective in lung cancer always is to try and catch it early before damage is done. This technique may help us do that and save lives,” Daniel said.

Collaborating with colleagues in U.Va’s radiology and physics departments, Daniel first tested three technetium-99 radiotracers on rat lungs: MAA, unfiltered sulfur colloid (SC) and pertechnetate. Imaging was performed on the animals, where more precise localization was found with the MAA radiotracer.

Thirteen patients referred to U.Va. with a suspicious lung nodule on a conventional CT scan were then selected for a human study after informed consent was obtained. Twelve of the thirteen were current or former smokers. All thirteen had their lung lesions successfully localized using a radiotracer probe. The lesions were then biopsied using a thoracoscope. Five lesions were found to be lung cancers. These patients immediately underwent a lobectomy through a larger incision- the standard treatment for lung cancer. Two other patients were found to have malignant nodules, but they were solitary lesions from a previous cancer removed from another part of the body. These nodules were removed by video surgery. In five patients, the lung nodules were benign. They recovered uneventfully from video surgery. 

“If further clinical use of this technique confirms that it is reliable, with low morbidity and mortality,” Daniel said, “proceeding directly to radiotracer-guided video surgery may become the safest step to take if a patient with a significant smoking history is found to have a solitary, small lung nodule. Presently, most of these patients are advised to have repeat CT scans, an experience that can be very anxiety producing.”

Contributing to the study on localization of small pulmonary lesions with Daniel were: Dr. Talissa Altes, Dr. Spencer Gay, Dr. Patrice Rehm, and Dr. Mark Williams of U.Va’s department of radiology; Dr. David Jones of U.Va.’s thoracic surgery section; and Alexander Stolin of U.Va.’s physics department. The study can be found on the web at http://ats.ctsnetjournals.org/.

May 4, 2004