개의 후각능력을 이용한 암세포 특이성분 탐지에 관한 연구

Abstract

Purpose : The basic unit for living things is a cell. Each cell survives through its own metabolic process. However, a cancerous cell has different metabolism from a normal cell. Due to such differences it produces specific chemicals which a normal cell does not. This study hypothesizes that some kinds of cancerous odor can be detected by a dog's remarkable sense of smell because metabolic products of cancerous cell emit a unique odor.

Materials : Experiments in this research can be categorized into 2 parts. The first part of the experiments is to determine whether a trained dog could distinguish media used to culture breast cancer cells and colonic cancer cells from controls consisting of pure medium samples and those used to grow normal cells of swine embryo. The second part of the experiments is to determine whether a trained dog could distinguish the urine samples from mice with breast and colonic cancer from normal urine samples taken from the same mice before they became cancerous by being injected with 2 kinds of cancer cells.

Methods : Two household dogs without any kind of previous training, both males and aged 2 years, were used in this study. They were initially trained to recognize and remember the odor of cancerous medium samples through the reward-based approach in which they were ordered to sit and immediately rewarded by presenting a dummy or a tennis ball and praised once they had sniffed the cancerous medium samples. After that phase, they were repeatedly trained to discriminate between the cancerous medium sample(target) and normal medium samples(non-targets). When the dogs were sure to identify the 2 types of cancerous media, they were trained to distinguish any of target samples from the plural controls(2-3 non-cancerous medium samples). In the same manner, the dogs were instructed to identify urine samples from mice with breast and colonic cancers in the line-up of 5 urine samples(combination of 1 target sample and 4 control samples). The urine sample tests were conducted on several kinds of occasions.

Results : During the tests of discriminating cancerous media and non-cancerous media, both dogs correctly identified the target media with a sensitivity of 95%. Also the dogs could distinguish the cancerous urine samples of mice from the control samples with the same success rate of 95%.

Conclusion : This study strongly suggests that cancerous cells produce specific chemicals which have unique odor markers, which can be detected by dogs' olfactory function and that cancer-related metabolic products are made and defecated from the very early stage of cancer development so a trained dog can signal whether or not an animal has cancer in its body after smelling its urine sample irrespective of its disease stage.

After additional in-depth study into a variety of cancers in people through the test of men's urine or blood by means of dogs' olfaction, based on this study, we may expect that early diagnosis of cancer will be possible.