Dithiothreitol homogenization of prefixed sputum for lung cancer detection.

The technique of chemical homogenization of sputum for cancer detection was revisited. The mucolytic agent dithiothreitol (DTT) had been used by the authors on fresh specimens. In this study, its effectiveness in homogenizing prefixed sputum was investigated. Fifty-seven positive samples were examined: 28 were prefixed with 2% carbowax in 60% ethanol and 29 in 3% carbowax in 60% ethanol. Each specimen was divided equally into three parts and homogenized immediately, 3 and 7 days later, respectively, with 0.2% (0.013 mol/L) DTT in the respective prefixative. Five samples were prefixed for 4 wk before homogenization. The homogenization time varied from 30 min to 48 hr. The cellular morphology was compared to directly smeared controls from the same samples. It was found that the cellular morphology was well preserved and best with the 3% carbowax in 60% ethanol. The specimen could be prefixed for up to 4 wk before homogenization and the homogenization process could last from 30 min to 48 hr without any damaging effect on morphology. Furthermore, screening was made easy with the mucus lysed and its obscuring effect removed and the cells concentrated and evenly distributed. The method was versatile and could be of value in enhancing the detection rate of cancer in sputum.