There is an idea that allergy may cause a reduced sensitivity to certain carcinogens and consequently diminish the risk of developement of malignant tumours. The analysis of published researches seems to confirm the lower incidence of solid tumours mainly in locations that have contact with the outside world. These defined group of tumors are predominantly epithelial cancer – oral cavity, pharyngeal, laryngeal, colorectal, pancreatic and gliomas. There is a suggestion that the hyperactivity of the immune system we deal in allergies may facilitate getting rid of unwanted carcinogens or their transporters. The other localizations such as breast, prostate or haematologic malignancies showed less frequent or any correlation. On the other hand recent studies have indeed signaled the percentage increase in the risk of breast cancer, lung, and prostate cancer in patients with allergic diseases. This what fastened the two groups of diseases is the environmental background. It should be noted that the analysis of cross-correlation between the diseases relates to epidemiological studies in adults and includes mostly solid tumors having lesser extent to hematological disorders. The two hypotheses were developed for the purpose of networking with each other allergies and cancer. It regarded the influence of a hypersensitivity reaction initiated by immunological mechanisms on the process of carcinogenesis.