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Hexavalent chromium (Cr(VI)) compounds are recognized as carcinogens in the respiratory tract, giving rise to cancers of the lung, nose and nasal sinuses, especially in certain occupational environments. Inhalation exposure of Cr(VI)-containing particles, dusts and fumes commonly occurs in chromium-related occupational environments, such as chromium production, plating, welding of chromium-containing metals and alloys, electroplating, chromium-containing pigments and paints. Epidemiological surveys of chromium compounds have shown strong associations between exposure to Cr(VI) and mortality due to lung cancer, as well as positive associations with cancers of the nose and nasal cavity. Nasal symptoms, such as nasal irritation, ulceration and perforation of the nasal septum, nasal turbinate engorgement and hypertrophy, are important signs for the early diagnosis of lung cancer and cancers of the nose and nasal cavity in those with an occupational history of Cr(VI) exposure. Cr(VI) exposure in the workplace remains a serious problem as a cause of lung cancer and cancers of nose and nasal cavity, especially in relatively small enterprises that use chromium compounds. Appropriate protection for workers should be considered in occupations that involve exposure to chromium compounds.

Endobronchial ultrasonography with a guide sheath (EBUS-GS) has recently been used for improved diagnostic yields for peripheral pulmonary lesions. This study retrospectively evaluated the factors related to the diagnostic yield of EBUS-GS for peripheral lung cancer. The medical records of 76 patients who had been diagnosed with lung cancer and had undergone bronchoscopy with EBUS-GS in our hospital between August 2014 and September 2015 were reviewed. The total diagnostic ratio of peripheral lung cancer was 71.1%. The following factors of the diagnostic yield were evaluated: location of pulmonary lesion; size; feature; bronchus sign; location of EBUS probe; EBUS detection; number of biopsies performed; procedure time; use of virtual bronchoscopic navigation; use of EBUS-guided transbronchial needle aspiration with EBUS-GS; CT slice thickness; operator's years of medical experience; and specialized training in bronchoscopy at the National Cancer Center. In all cases, lesion size ≧ 20 mm (80.8% vs. 50.0%, P = 0.006), EBUS probe location "within" (90.0% vs. 50.0%, P < 0.001), EBUS detection (80.7% vs. 28.6%, P < 0.001), number of biopsies ≧ 5 (78.0% vs. 47.1%, P = 0.013), and bronchoscopy training (81.6% vs. 60.5%, P = 0.043) significantly contributed to an increase in the diagnostic yield. Following a multivariate analysis, EBUS probe location "within" was found to be the most significant factor affecting the diagnostic yield (odds ratio 14.10, 95% CI 3.53-56.60, P < 0.001), and bronchoscopy training was the second most significant factor (odds ratio 6.93, 95% CI 1.86-25.80, P = 0.004). EBUS probe location "within" and bronchoscopy training are the most important factors for improved diagnostic yield by bronchoscopy with EBUS-GS for peripheral lung cancer.