IASLC: Phototherapy Produces High Response in Centrally Located Early Lung Tumors

SEOUL, South Korea, Sept. 7 -- More than 90% of cases of centrally located lung tumors saw complete response to photodynamic therapy and there were few recurrences, according to results of a small study.

All 54 lesions had objective responses to the therapy, including 50 complete responses, Jitsuo Usuda, M.D., of Tokyo Medical University reported at the International Association for the Study of Lung Cancer's world conference here.

The key to the high success rate is the integration of an autofluorescence diagnostic system into a videoendoscope, he added.

"Red fluorescence emitted from the tumor allowed accurate determination of the tumor margin just before photodynamic therapy," said Dr. Usuda. "This novel photodiagnostic system improved the quality and efficacy of photodynamic therapy and avoided misjudgment of doses of laser irradiation."

The study represents a continuation of the Japanese investigators' evaluation of photodynamic diagnosis and photodynamic treatment of early-stage, centrally located lung cancer. The system combines the tumor-selective photosensitizer talaporfin sodium and laser irradiation.

The current study involved the investigators' most recent technologic development, incorporating autofluroescence diagnostic capability into the SAFE-3000 videoendoscope for use with the laser photodynamic therapy.

Candidates for photodynamic therapy consisted of those who were deemed unsuitable for surgery because of underlying cardiopulmonary dysfunction or who chose not to have surgery.

Centrally located tumors were defined as lesions located in the region from the tracheal bifurcation to the subsegmental bronchi. Peripheral margins had to be visible on endoscopy. The patients otherwise had normal chest x-rays and CT images. Patients with lymph node involvement or distant metastases were excluded.

Early-stage disease was defined as carcinoma in situ or limited invasion into the bronchial wall but not beyond the cartilage. Tumors could be no more than 2 cm in diameter.

Dr. Usuda said the photosensitizer and laser irradiation destroy tumors by combining elements of cytoxic therapy, immunologic therapy, and anti-angiogenic therapy.

Tumor depth was evaluated by endobronchial ultrasound and optical coherence tomography. Peripheral margins were visualized by the photodiagnostic system of autofluorescence bronchoscopy (SAFE-3000).

Lesions were localized on the basis of red fluorescence emission produced by the diagnostic system. Photodynamic therapy was performed with a 664 nm diode laser, delivering 100 J/cm² of energy to the tumor.

Dr. Usuda and colleagues treated 40 male patients, whose 54 tumors were all squamous cell. Disease stage was 0 in 50 lesions and 1 in the remaining four. Endoscopic evalulation showed that 50 lesions were thickened, three were polypoid, and one was nodular.

For lesions that were 1 cm or smaller (N=42), photodynamic therapy produced complete responses in 39 and partial responses in three.

Among the 12 larger tumors, therapy resulted in 11 complete responses and one partial response. Dr. Usuda said seven recurrences have occurred in followup for as long as five years.

Length of hospitalization after treatment is seven to nine days, which is briefer than the stay associated with conventional photofrin photodynamic therapy, said Dr. Usuda. As a result the talaporfin-based photodynamic therapy might be more cost effective for treatment of early-stage, centrally located lung tumors.