Robert E. Beck and Dr. Ray M. Merrill, Health Sciences

There has been some research conducted on the relationship between allergies and cancer. The goal of our research was to be able to compile all information in the medical literature in order for the associations between allergies and specific cancer sites (i.e. breast, prostate. etc.) might be compared. We wanted to find out what associations, if any exist between allergies and specific cancer sites. Now that the associations have been found it is hoped that future research will support this research as well as use this information to establish how and why these associations occur.

Several studies have explored the relationship between allergies and cancer, with some of these studies considering the potential association of allergies with a range of cancer sites. Cancer site-specific reviews have been conducted on the topic. However, no review has attempted to evaluate the association between allergies and cancer for a range of cancer sites. This review considers the existing literature on the potential link between allergies and cancer. Considering multiple cancer sites may provide greater insight into the causal mechanisms that may associate allergies with cancer. Potential causal mechanisms and clinical implications will be discussed.

Many of the studies identified show a link between allergies and cancer. For all sites combined there does not seem to be a consistent association between allergies and cancer. However, some of the specific cancer sites provide evidence of a possible association with allergy.

Several studies show a decreased risk for certain cancer sites associated with allergy. Among brain tumors, there does not seem to be an association with allergy, except with the specific type glioma, where four studies showed a decreased risk among allergic persons and one study found no association. Most of the results from studies on colorectal cancer seem to indicate a decreased risk associated with allergy. Four studies on colorectal cancer observed this decreased risk, while one found and increased risk related to allergy. Both studies on cancer of the larynx show a decreased risk among persons with allergies. Of the five studies concerning Non-Hodgkin’s Lymphoma (NHL), four show a decreased risk for NHL among allergic individuals, and one shows no association. Two of the studies that found a decreased risk, observed this decreased risk only for allergies to plant and animals and nuts and berries, respectively. Both studies on cancer of the oesophagus found a decreased risk related to allergy. All three studies on oral cancer found a decreased risk associated with allergy. Four studies on pancreatic cancer found a decreased risk among persons with allergies. However, one study found an increased risk and one found no association. Both studies on stomach cancer show a decreased risk related to allergy. Likewise, both studies on uterine body cancer show a decreased risk.

There were also several studies that show an increase in risk of certain cancer sites among individuals with allergies. Both of the studies involving bladder cancer show an increased risk associated with allergy. In the two studies done involving lymphoma, both show an increased risk among allergic individuals. Most of the research on myeloma indicates an increased risk associated with allergy. Five studies have found an increased risk among persons with allergy. However, one study found a decreased risk and one found no association. Both studies on prostate cancer found an increased risk associated with allergy.

Some studies found no association between allergy and cancer risk or an association was not clear from the studies conducted. For example, among studies involving breast cancer, two reported a decreased risk associated with allergy, two reported an increased risk, and one found no association. The association is also not clear among leukemia patients. Five studies show a decreased risk for leukemia associated with allergy, three show an increased risk, one shows no association, and one shows and increased risk associated with eczema and no association with asthma or hay fever. Lung cancer also shows conflicting results. Two studies show a decreased risk associated with allergy, three show an increased risk and two show no association. An association could not be determined based on the results from the three studies on melanoma. Two studies showed an increased risk for melanoma (one study found this true only among men), and one showed a decreased risk associated with allergy. Of the two studies conducted evaluating the effect of allergy on thyroid cancer, one showed a decreased risk for thyroid cancer and one showed an increased risk.

Three cancer sites have been evaluated by only one study each. Associations from these studies need further research to support these findings. Kaposi’s sarcoma showed an increased risk associated to allergy. Liver cancer found a decreased risk associated with drug allergies. Cancer of the ovary also showed a decreased risk among allergic individuals.

Further research is needed for all cancer sites in relation to allergies, in order to support the findings of the present research. The sites where significant associations have been consistently observed are in particular need of further research. Through further research, we might come to understand why these associations exist. Such information may be helpful in understanding cancer and finding ways to combat it.