Optimization of light dosimetry for photodynamic therapy of Barrett's esophagus: efficacy vs. incidence of stricture after treatment.

BACKGROUND: Photodynamic therapy (PDT) may be used to ablate high-grade dysplasia/early stage cancer (HGD/T1) in patients with Barrett's esophagus. PDT may result in esophageal stricture. This nonrandomized, unblinded, dose de-escalation study in consecutive patients was designed to determine the lowest light dose effective for ablation of HGD/T1 while reducing the incidence of stricture. METHODS: A total of 113 patients received an injection of porfimer sodium (2 mg/kg). Three days later, 630 nm light was delivered by using a 20-mm-diameter PDT balloon at doses of 115 J/cm (n=59), 105 J/cm (n=18), 95 J/cm (n=17), or 85 J/cm (n=19). Treatment efficacy was determined by obtaining biopsy specimens of the treated area 3 months later. The incidence of stricture was determined by the need for esophageal dilation to treat dysphagia. A stricture was considered severe if 6 or more dilations were required. RESULTS: The incidence of severe stricture was related to the light dose. At 115 J/cm, 15.3% of patients developed severe strictures compared with 5.3% to 5.6% of those treated with the lower doses. At a light dose of 115 J/cm, 17.0% of patients had residual HGD/T1. Light doses of 105 J/cm, 95 J/cm, and 85 J/cm resulted in residual HGD/T1 in 33.3%, 29.4%, and 31.6% of patients, respectively. None of the observations were statistically significant. CONCLUSIONS: Decreasing the light dose below 115 J/cm appeared to result in a reduced incidence rate of severe stricture but higher relative frequencies of residual HGD/T1 in Barrett's esophagus.

Laser-induced fluorescence spectroscopy for in vivo diagnosis of non-melanoma skin cancers.

BACKGROUND AND OBJECTIVES: Laser-induced fluorescence spectroscopy is a non-invasive technique previously used for detection of cancer in a variety of organ systems. The objective of this study was to determine whether in vivo laser-induced fluorescence spectroscopy alone at the visible excitation wavelength of 410 nm could be used to detect non-melanoma skin cancers. STUDY DESIGN/MATERIALS AND METHODS: The system consisted of a nitrogen/dye laser tuned at 410 nm, an optical multichannel analyzer, and a fiber optic probe for excitation of tissue and collection of fluorescence emission. Two hundred and seventy nine measurements were performed from normal and abnormal tissues in 49 patients. Patients were classified as having either skin types I, II, or III. Biopsy of the abnormal tissues were then performed. Each measurement was assigned as either normal, basal cell carcinoma (BCC), squamous cell carcinoma (SCC), pre-cancerous, or benign. Total emission photon count was used as the discriminating index. A threshold value was calculated to separate normal tissue indices from indices of cancer tissues. The classification accuracy of each data point was determined using the threshold value. RESULTS: Cancers were classified 93, 89, and 78% correctly in patients with skin types I, II, and III, respectively. Normal tissues were classified 93, 88, and 50% correctly in patients with skin types I, II, and III, respectively. Using the same threshold, pre-cancerous spectra were classified 78 and 100% correctly in skin types I and III, respectively. Benign lesions were classified 100, 46, and 27% correctly in patient with skin types I, II, and III, respectively. CONCLUSIONS: In vivo laser induced fluorescence spectroscopy at 410 nm excitation and using the intensity of emission signal is effective for detection of BCC, SCC, and actinic keratosis, specially in patients with light colored skin.