[[en/index|English]] · [[zh/index|中文]] · [[en/classics/lin-peizhong-1986|EN]] · [[zh/classics/lin-peizhong-1986|中文]] ## Main findings of the Lin 1986 paper - Lin, P. Z.; Zhang, J. S.; Ding, Z. W. Carcinogenic and promoting effects of fish juice, preserved rice and salted dry fish on the forestomach epithelium of mice and esophageal epithelium of rats. Chinese Journal of Cancer (in Chinese, with English Abstract) 1986, 8 (5), 332–335. --- [Lin1986.pdf](https://www.dropbox.com/scl/fi/f0xpzobf2i2m5ugl79ilx/Lin1986.pdf?rlkey=agfv9g638kav4v2e15jmk8bbv&st=ki74it6y&dl=0) In high-incidence areas of esophageal cancer in southern China (i.e., the Chao Shan region, 潮汕地区), fish juice (fish sauce) is a commonly used condiment among local residents. Residents of Nan'ao County (南澳县), the epicenter, also have a habit of consuming preserved rice and dried fish. Lin et al. investigated the carcinogenic and tumor-promoting effects of fish juice, preserved rice, and dried fish using in vivo models. ### Materials: sources and preparation Fish juice (FJ): (a) **Homemade fish juice** from residents of Nan'ao County. It appeared turbid and brownish, with abundant sediments and impurities. (b) **Commercial fish juice** sold at grocery stores in Shantou City. It appeared transparent and dark brown, without sediments or impurities. The fish sauce was diluted to 33% and 50% aqueous solutions, then fed to mice (6 times/week, 0.6 mL per mouse per dose) and rats (6 times/week, 3 mL per rat per dose). Preserved rice and dried fish: Preserved rice was obtained from grain depots of production teams in Nan'ao County, and dried fish was collected from local residents' homes. Neither showed signs of mildew. The **preserved rice with husk** was ground into rice flour, mixed with 5% dried fish powder, and steamed into pellets for animal feeding. Nitrososarcosinethylester (NSEE): 20% (and 40%) ethyl sarcosinate hydrochloride was mixed in equal volumes with 3% (and 6%) NaNO2. The mixture was administered to mice (0.2 mL per 10 g body weight per dose) and rats (0.1 mL per 10 g body weight per dose) via gavage. ### English abstract > The carcinogenic and promoting effects of fish juice, preserved rice and salted dry fish from Nanau county, Guangdong province, a high incidence area of esophageal cancer, were studied in mice and rats. The homemade fish juice as well as fish juice in market, whether or not added with NaNO2, did not cause tumor in the forestomach of mice and the esophagus of rats. When the mice were intubated with an initiator, nitrososarcosinethylester (NSEE) twice, no carcinoma was found at the end of the experiment (D 120). Only papilloma appeared in the forestomach epithelium. The incidence was only 37.5%. However, when the mice were intubated with NSEE for 2 times followed by gastric doses of homemade fish juice, the tumor incidence in the forestomach was increased to 89.7%, in which 20.5% was carcinoma. The tumor and carcinoma incidences of initiator (NSEE and NMBzA) group and initiator + market fish juice group in mice and rats were without significant difference. The experimental results show that the **homemade fish juice proved distinct promoting effect on the process of cocarcinogenesis initiated by NSEE in the forestomach of mice, while the market fish juice has no significant promoting effect on the forestomach epithelium of mice and the esophageal epithelium of rats**. NSEE induced 31.6% carcinoma in the forestomach epithelium of mice on standard diet. While in mice fed with preserved rice and salted dry fish, the carcinoma incidence was increased to 63.6%. It appears that preserved rice and salted dry fish have promoting effect on the process of cocarcinogenesis initiated by NSEE in the forestomach of mice. ### Homemade fish juice: carcinogenic potency ![[Lin1986_Tab1.JPG]] ### Commercial fish juice: carcinogenic potency ![[Lin1986_Tab2.JPG]] ### Preserved rice and dried fish: carcinogenic potency ![[Lin1986_Tab3.JPG]] ## This early experiment is supported by the latest multidisciplinary evidence - Deep sequencing studies reveal that normal esophageal cells already harbor numerous cancer driver mutations ([Martincorena et al., 2018](https://www.science.org/doi/10.1126/science.aau3879)), suggesting that nitrosamine exposure alone is insufficient to cause esophageal cancer. - Whole-genome sequencing analyses of ESCC from high- and low-incidence regions have not detected mutational signatures specifically linked to nitrosamine intake ([Moody et al., 2021](https://www.nature.com/articles/s41588-021-00928-6)). These findings indicate that the striking difference in ESCC incidence between high- and low-risk areas is unlikely due to mutagens like nitrosamines, but rather to non-mutagenic tumor promoters. - Mutations can remain dormant in normal tissues for life, and only under pro-tumorigenic stimuli such as cell proliferation and chronic inflammation do they undergo malignant transformation; **the promotion stage acts as the rate-limiting step** of cancer development ([Balmain, 2020](https://www.nature.com/articles/s41588-020-00727-5); [Li et al., 2025](https://aacrjournals.org/cancerdiscovery/article/15/6/1115/762586/Long-Term-Latency-of-Highly-Mutated-Cells-in)). ## What could be the tumor promoters in homemade fish sauce? A prime suspect is diatom silica needles. Our team detected massive needle-like diatom frustules in fish sauce processing residues, with abundances reaching 330,000 per gram ([Wu et al., 2026](https://www.dropbox.com/scl/fi/w0kt6qptjxje8g4avqxid/Wu2026_IJC.pdf?rlkey=xuv11pvshmb2m4v7nb8vqq4iv&st=v1wrywee&dl=0)). These diatom frustules measure 20–200 μm in length; analogous to silica fibrous phytolith contaminants in wheat flour from North China (another high-risk region of esophageal cancer), they may trigger repeated injury and chronic inflammation of the esophageal mucosa during ingestion. By contrast, commercial fish sauce underwent fine filtration (e.g., 0.1 μm pore size) before bottling to remove these diatom frustules, and thus exhibited no tumor-promoting effects.