In 1980, the BBC (British Broadcasting Corporation) visited Linxian (now Linzhou City) in Henan, China, to shoot a documentary titled The Cancer Detectives of Lin Xian, showcasing China’s research and efforts in the prevention and treatment of esophageal cancer. This documentary drew global attention to the situation of esophageal cancer in China. A harsh reality faced by China is that it is a high-incidence country for esophageal cancer, with over half of the global cases. The incidence of esophageal cancer in China is notably concentrated in the Taihang Mountain area, with Linxian being one of the regions with the highest incidence, prevalence, and mortality rates of esophageal cancer.
In the 1950s, Yang Gui, the county party secretary of Linxian, mentioned at a national meeting on mountain production that the people of Linxian faced a dilemma of "no water, no roads, and no esophagus," which caught the attention of Premier Zhou Enlai. In 1959, in response to Premier Zhou's call, Henan Medical University led the formation of the "Henan Medical Team" to be stationed in Linxian.
Among the team was a middle-aged man named Shen Qiong (1911-2005), who was the deputy director of the Pathology Department at Henan Medical University. Upon hearing about the esophageal cancer situation in Linxian, he decided to join the medical team. Shen Qiong realized that the key to tackling esophageal cancer was early detection. However, at that time, most patients were diagnosed at an advanced stage, with a very low survival rate, averaging only about 10 and a half months of survival. In order to study the early pathological characteristics of esophageal cancer to screen for early-stage patients, Shen Qiong began developing a device that could collect esophageal cells.
Initially, Professor Shen tried to swallow a finger cot attached to the end of a gastric tube and inflate it to collect esophageal cells, but it was unsuccessful. Later, inspired by the local women’s net-like headpieces, he improved the device by attaching a net to a balloon and successfully obtained esophageal epithelial cells for diagnosis. After continuous research and improvement, he eventually developed the "Plastic Double-Lumen Balloon Esophageal Cell Collector." The sampling principle of the device was to insert the uninflated balloon into the esophagus, inflate it after reaching the stomach, and the fine cotton thread net on the balloon would rub against the esophagus to collect cells for subsequent cytological examination. This method, known as "netting," was a breakthrough in early detection of esophageal cancer, though it caused some discomfort for patients and had certain diagnostic limitations. It is no longer in use today, but it undeniably made a significant contribution to the early detection and prevention of esophageal cancer in China and some other developing regions.
At almost the same time, Japan across the ocean was also exploring early esophageal cancer screening devices. In Japan, esophageal cancer diagnosis mainly relied on X-rays and endoscopy, but these methods were not ideal for early-stage diagnosis, as only 245 early cases were detected over 15 years.
In 1976, Professor Nabeya Kinichi (fig. 3) from Kyorin University School of Medicine in Japan invented the "Capsule-type Esophageal Cell Scraping Diagnostic Tool" (literally translated as “Capsule-type Esophageal Friction Cell Diagnostic Device”) for early screening of esophageal cancer. The basic principle of this device (fig. 4) was to place a sponge attached to a string inside a capsule, which, once swallowed, dissolved in the stomach, releasing the sponge. The string was then pulled out to collect cells by the sponge as it passed through the esophagus.
During the invention process, Professor Nabeya made multiple optimizations. Initially, three different types of sponges were tested (fig. 5). The first sponge was made of HR30 polyurethane, which was highly compressible and resilient, but too soft to collect sufficient cells. The second sponge improved on this by wrapping an ES fiber nonwoven fabric around it, enhancing cell collection capability, but the fabric made the sponge too rigid, making swallowing uncomfortable. Ultimately, the third sponge, made of HRY06 polyurethane with larger pores and thicker fibers, proved ideal for clinical use. The capsule shell was a standard gelatin capsule that could dissolve in 3-4 minutes in the stomach. From September 1976, Professor Nabeya and his team began large-scale screening for early esophageal cancer using this sponge capsule.
So, which device is better, Professor Shen’s balloon or Professor Nabeya’s sponge capsule? The answer is not as straightforward as it may seem. In 1997, researchers from China and the US conducted a comparative experiment in Linxian, Henan, comparing the balloon and sponge capsule sampling devices for early esophageal cancer screening. The results showed that the balloon device had a higher sensitivity and specificity in obtaining cell samples and detecting esophageal cancer and precancerous lesions. Remarkably, nearly all participants were able to successfully swallow the balloon, but 14% of participants could not complete the sponge capsule sampling. Researchers believed this could be due to the participants' previous experience with the balloon device and their unfamiliarity with the new sponge capsule. Additionally, the sponge's string was not stiff enough, increasing sampling difficulty. However, many participants preferred the sponge capsule sampling method. The study also noted that both devices had room for improvement.
In the 21st century, sponge capsule sampling devices developed rapidly. Products like EsophaCap? and Cytosponge? from abroad, and a 2018 device developed by a medical equipment company in Nanjing, China, followed similar principles to Professor Nabeya’s original invention (fig. 6).
While it seemed like Professor Shen’s balloon device was gradually fading from the scene, its design concept was not forgotten. In 2019, Lucid Diagnostics, an American medical device company, developed EsoCheck?, which was approved by the FDA. This device surpassed 90% sensitivity and specificity for esophageal cancer detection (fig. 7).
The basic principle of this product involved swallowing a capsule with a small balloon connected to a thin silicone tube. After reaching the stomach, the balloon was inflated, and the device gently brushed cells from the esophageal lining as it was pulled back. It is easy to see the influence of Professor Shen’s balloon device in this modern product.
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