On the apparent rarity of epithelial cancers in captive chimpanzees

Abstract

Malignant neoplasms arising from epithelial cells are called carcinomas. Such cancers are diagnosed in about one in three humans in 'developed' countries, with the most common sites affected being lung, breast, prostate, colon, ovary and pancreas. By contrast, carcinomas are said to be rare in captive chimpanzees, which share more than 99% protein sequence homology with humans (and possibly in other related 'great apes'-bonobos, gorillas and orangutans). Simple ascertainment bias is an unlikely explanation, as these nonhuman hominids are recipients of excellent veterinary care in research facilities and zoos, and are typically subjected to necropsies when they die. In keeping with this notion, benign tumours and cancers that are less common in humans are well documented in this population. In this brief overview, we discuss other possible explanations for the reported rarity of carcinomas in our closest evolutionary cousins, including inadequacy of numbers surveyed, differences in life expectancy, diet, genetic susceptibility, immune responses or their microbiomes, and other potential environmental factors. We conclude that while relative carcinoma risk is a likely difference between humans and chimpanzees (and possibly other 'great apes'), a more systematic survey of available data is required for validation of this claim.

Nesting of colon and ovarian cancer cells in the endothelial niche is associated with alterations in glycan and lipid metabolism

“…A direct impact of glycosylation on the cell-cell adhesion, contributing to cancer invasiveness and metastasis was reported in several studies22232425. For instance, significantly altered UDP-glucuronate and UDP-glucosamine can be deployed for glycosylation as separate units or can serve as substrates for hyaluronan biosynthesis, which also is involved in cellular membrane glycosylation26. Furthermore, increased synthesis of hyaluronan was associated with malignant progression in several cancers, including ovarian and colon cancer27; its role in tumor growth and progression in vivo as well as in malignant transformation was previously reported28.…”

Peto's paradox and the hallmarks of cancer: constructing an evolutionary framework for understanding the incidence of cancer

“…The study of the cells of different rodent species in culture both supported the expectations of the evolutionary model and revealed novel species-specific anti-cancer strategies (table 1). Furthermore, interest in comparative approaches that exploit data from non-model species are rapidly increasing [26][27][28][29], so that we can anticipate further tests of the evolutionary model. The domestic dog is a species notable for having an extensive dataset and studies of breedspecific differences in cancer risk are already proving to be productive [28][29][30].…”

Peto's paradox and the promise of comparative oncology

“…Surprisingly, captive chimpanzees have not been found to have the same high rates of carcinoma. As discussed by Varki & Varki [48], ascertainment bias is a concern, although many zoo veterinarians perform necropsies as described above and the observed carcinoma rate in chimpanzees remains relatively low. Varki & Varki offer several explanations for the different carcinoma rate between such genetically similar primates as chimpanzees and humans including inadequacy of numbers surveyed, differences in life expectancy, diet (chimpanzees do not eat highly processed foods like humans), genetic susceptibility, immune responses or their microbiomes, and other potential environmental factors (chimpanzees do not smoke like humans).…”

“…In this issue, Varki & Varki [48] discuss the common occurrence of carcinomas originating from epithelial tissue in humans (including lung, breast, prostate, colon, ovary and pancreas). Surprisingly, captive chimpanzees have not been found to have the same high rates of carcinoma.…”