Mosquito coil exposure associated with small cell lung cancer: A report of three cases

Abstract

Mosquito coils, which are commonly used as residential insecticides in Asia, contain different concentrations of octachlorodipropyl ether (S-2) as a synergist or an active ingredient. As bis(chloromethyl) ether (BCME) is an extremely potent lung carcinogen that can be produced by the thermolytic degradation of S-2, contact with mosquito coils is likely to expose individuals to a certain level of BCME, and therefore increase the risk of lung cancer. However, the significance of exposure is uncertain, as clinical and epidemiological studies concerning mosquito coil users and workers are lacking. The present study describes three cases of small cell lung cancer treated at the Shanghai Pulmonary Hospital that were likely to be the result of exposure to mosquito coils. All patients had worked in the mosquito coil manufacturing industry, with an mean occupational duration of 9.1 years, and presented with similar respiratory symptoms, such as cough and dyspnea. Upon diagnosis, no metastasis to other organs was identified in any of the cases. Subsequently, the three patients were treated with chemotherapy as well as radiotherapy in one case, however, all patients succumbed to the disease, with a mean overall survival time of 10.7 months. We conclude that contact with mosquito coils is likely to expose individuals to a level of S-2 that may increase the risk of SCLC.

Keywords: insecticide; lung carcinogen; occupational exposure; octachlorodipropyl ether.

Figure 1

Case one: Representative images from radiography and chest CT revealing the presence of a mass in the upper lobe of the left lung. (A) Radiograph prior to treatment. (B) Representative CT prior to treatment. (C) Representative CT image after two cycles of first-line chemotherapy. (D) Representative CT image showing progressive disease after six cycles of first-line chemotherapy. CT, computed tomography.

Figure 2

Case two: Representative images from radiography and chest CT revealing the presence of a mass in the upper lobe of the left lung and enlarged lymph nodes. (A) Radiograph prior to treatment. (B) Representative CT image prior to treatment. (C) Radiograph after one cycle of first-line chemotherapy treatment. CT, computed tomography.

Figure 3

Case three: Representative images from radiography and chest CT revealing the presence of a mass in the middle lobe of the right lung, pleural effusion and enlarged lymph nodes. (A) Radiograph prior to treatment. (B) Representative CT image prior to treatment. (C) Representative CT image after two cycles of first-line chemotherapy. (D) Representative CT image after superior vena cava stenting. (E) Representative CT image after thoracic radiation therapy and four cycles of second-line chemotherapy. (F) Representative CT image showing progressive disease after second-line chemotherapy. CT, computed tomography.

Figure 4

Histological analysis of endobronchial biopsy specimens from cases one, two and three (magnification, ×100). H&E, hematoxylin and eosin; TTF-1, thyroid transcription factor 1; SYN, synaptophysin; NSE, neuron-specific enolase; CD, cluster of differentiation.