Heavy Metals and Cancer: A Study on Canine Tumours and Environmental Bioindicators

Pets (i.e., dogs and cats) due to their spontaneous tumour development in shared environments with humans and their genetic, immunological, and molecular similarities, serve as valuable comparative oncology models. Heavy metals such as cadmium (Cd) have been recognized as potent environmental carcinogens with severe consequences for both human and animal health. Chronic exposure to these toxicants has been linked to various malignancies, including lung, breast, prostate, and kidney cancers. Given their persistence in ecosystems and ability to bioaccumulate, heavy metals represent a significant threat to long-term health, particularly in urban and industrialized areas. This study describes occurrence in pets of tumours affecting the skin, soft tissues, mammary glands and penis and testicles, in areas with varying levels of Cd pollution.
The dataset included a population of 1,764 dogs, 1,057 females (480 neutered) and 707 males (204 neutered). To evaluate the potential contribution of metal pollution to tumour occurrence, a univariate and multivariate mixed-effects Poisson generalized linear model (GLM) has been developed to analyse both fixed and random effects.
Areas with very high Cd pollution showed higher proportion of mammary gland tumours (PMR = 64.67; 95%IC: 33.39-125.252), penis and testicular tumours (PMR = 19.77; 95%IC: 2.77-141.30), soft tissue tumours (PMR = 100.55; 95%IC: 37.19-271.79), and skin tumours (PMR = 116.24; 95%IC: 72.67-185.94).
These results suggest that environmental Cd pollution can play a role into the development of mammary gland, penis and testicular tumours, skin and soft tissue tumours in dogs. This link between environmental pollution and tumour onset underscores the value of comparative oncology in understanding cancer aetiology and improving public health strategies.

宠物（即犬与猫）由于与人类共享生存环境时可自发产生肿瘤，且在遗传、免疫及分子层面与人类具有高度相似性，因此成为极具价值的比较肿瘤学（comparative oncology）模型。镉（Cd）等重金属已被证实为强效环境致癌物，对人类与动物健康均会造成严重危害。长期暴露于这类有毒物质，与肺癌、乳腺癌、前列腺癌及肾癌等多种恶性肿瘤的发生密切相关。鉴于重金属在生态系统中具有持久性且可发生生物富集（bioaccumulate），其对生物体的长期健康构成显著威胁，在城市与工业化地区尤为如此。本研究针对镉污染水平各异的区域，调查了宠物罹患皮肤、软组织、乳腺以及阴茎与睾丸肿瘤的情况。
本数据集涵盖1764只犬的研究群体，其中雌性1057只（480只为绝育犬），雄性707只（204只为绝育犬）。为评估重金属污染对肿瘤发生的潜在影响，本研究构建了单变量与多变量混合效应泊松广义线性模型（Poisson generalized linear model，GLM），用于分析固定效应与随机效应。
镉污染程度极高的区域，其宠物罹患乳腺肿瘤（PMR=64.67；95%IC：33.39-125.252）、阴茎与睾丸肿瘤（PMR=19.77；95%IC：2.77-141.30）、软组织肿瘤（PMR=100.55；95%IC：37.19-271.79）以及皮肤肿瘤（PMR=116.24；95%IC：72.67-185.94）的比例显著更高。
上述结果表明，环境镉污染可能参与犬的乳腺肿瘤、阴茎与睾丸肿瘤以及皮肤和软组织肿瘤的发生发展过程。这种环境污染与肿瘤发生之间的关联，进一步凸显了比较肿瘤学在解析癌症病因以及优化公共卫生策略方面的重要价值。