Acute infections as a means of cancer prevention: opposing effects to chronic infections?

PURPOSE

Epidemiological studies have found an inverse association between acute infections and cancer development. In this paper, we review the evidence examining this potentially antagonistic relationship.

METHODS

In addition to a review of the historical literature, we examined the recent epidemiological evidence on the relationship between acute infections and subsequent cancer development in adult life. We also discuss the impact of chronic infections on tumor development and the influence of the immune system in this process.

RESULTS

Exposures to febrile infectious childhood diseases were associated with subsequently reduced risks for melanoma, ovary, and multiple cancers combined, significant in the latter two groups. Epidemiological studies on common acute infections in adults and subsequent cancer development found these infections to be associated with reduced risks for meningioma, glioma, melanoma and multiple cancers combined, significantly for the latter three groups. Overall, risk reduction increased with the frequency of infections, with febrile infections affording the greatest protection. In contrast to acute infections, chronic infections can be viewed as resulting from a failed immune response and an increasing number have been associated with an elevated cancer risk.

CONCLUSION

Infections may play a paradoxical role in cancer development with chronic infections often being tumorigenic and acute infections being antagonistic to cancer.

Dr William Coley and tumour regression: a place in history or in the future

Spontaneous tumour regression has followed bacterial, fungal, viral, and protozoal infections. This phenomenon inspired the development of numerous rudimentary cancer immunotherapies, with a history spanning thousands of years. Coley took advantage of this natural phenomenon, developing a killed bacterial vaccine for cancer in the late 1800s. He observed that inducing a fever was crucial for tumour regression. Unfortunately, at the present time little credence is given to the febrile response in fighting infections—no less cancer.

Rapidly growing tumours contain large numbers of leucocytes. These cells play a part in both defence and repair; however, reparative functions can also support tumour growth. Intratumoural infections may reactivate defensive functions, causing tumour regression.

Can it be a coincidence that this method of immunotherapy has been “rediscovered” repeatedly throughout the centuries? Clearly, Coley’s approach to cancer treatment has a place in the past, present, and future. It offers a rare opportunity for the development of a broadly applicable, relatively inexpensive, yet effective treatment for cancer. Even in cases beyond the reach of conventional therapy, there is hope.

Dr William Coley and tumour regression: a place in history or in the future

Spontaneous tumour regression has followed bacterial, fungal, viral, and protozoal infections. This phenomenon inspired the development of numerous rudimentary cancer immunotherapies, with a history spanning thousands of years. Coley took advantage of this natural phenomenon, developing a killed bacterial vaccine for cancer in the late 1800s. He observed that inducing a fever was crucial for tumour regression. Unfortunately, at the present time little credence is given to the febrile response in fighting infections-no less cancer. Rapidly growing tumours contain large numbers of leucocytes. These cells play a part in both defence and repair; however, reparative functions can also support tumour growth. Intratumoural infections may reactivate defensive functions, causing tumour regression. Can it be a coincidence that this method of immunotherapy has been "rediscovered" repeatedly throughout the centuries? Clearly, Coley's approach to cancer treatment has a place in the past, present, and future. It offers a rare opportunity for the development of a broadly applicable, relatively inexpensive, yet effective treatment for cancer. Even in cases beyond the reach of conventional therapy, there is hope.

Spontaneous regression: a hidden treasure buried in time

Spontaneous tumor regression is a phenomenon that has been observed for hundreds, if not thousands of years. Although the term spontaneous implies 'without apparent cause', a review of case reports over the last several hundred years demonstrates that regression generally coincides with acute infections. Observations of this non-specific effect led to the emergence of active cancer immunotherapies by the 1700s. By the 1890s, William Coley refined this approach with a bacterial vaccine which, when administered properly, could induce complete regression of extensive metastatic disease. Unfortunately, after Coley's death, his vaccine and technique fell into obscurity. Modern approaches to treatment have reduced the occurrence of spontaneous regressions. Aseptic techniques and antibiotics significantly reduce postoperative infections, while chemotherapy and radiation impair immune activation even when an infection does occur. More than a century after its inception, Coley's vaccine and aggressive approach to treatment may still be one of most effective immunotherapies for cancer.

Elemental and radioactive analysis of commercially available seaweed

Edible seaweed products have been used in many countries, specifically Japan, as a food item. Recently these products have become popular in the food industry because of a number of interesting medicinal properties that have been associated with certain edible marine algae. Very little control exists over the composition of these products, which could be contaminated with a number of agents including heavy metals and certain radioactive isotopes. Fifteen seaweed samples (six local samples from the coast of British Columbia, seven from Japan, one from Norway and one undisclosed) were obtained. All samples were analyzed for multiple elements, using ICP mass spectrometry and for radioactive constituents. It was found that six of eight imported seaweed products had concentrations of mercury orders of magnitude higher than the local products. Lead was found at somewhat higher concentrations in only one local product. Laminaria japonica had the highest level of iodine content followed by Laminaria setchellii from local sources. Only traces of cesium-137 were found in a product from Norway and radium-226 was found in a product from Japan. Arsenic levels were found to be elevated. In order to estimate the effect of these levels on health, one needs to address the bioavailability and the speciation of arsenic in these samples.

Hypothesis: iodine, selenium and the development of breast cancer

BACKGROUND

In this paper we examine some of the evidence linking iodine and selenium to breast cancer development. Seaweed is a popular dietary component in Japan and a rich source of both of these essential elements. We hypothesize that this dietary preference may be associated with the low incidence of benign and malignant breast disease in Japanese women. In animal and human studies, iodine administration has been shown to cause regression of both iodine-deficient goiter and benign pathological breast tissue. Iodine, in addition to its incorporation into thyroid hormones, is organified into anti-proliferative iodolipids in the thyroid; such compounds may also play a role in the proliferative control of extrathyroidal tissues. Selenium acts synergistically with iodine. All three mono-deiodinase enzymes are selenium-dependent and are involved in thyroid hormone regulation. In this way selenium status may affect both thyroid hormone homeostasis and iodine availability.

CONCLUSION

Although there is suggestive evidence for a preventive role for iodine and selenium in breast cancer, rigorous retrospective and prospective studies are needed to confirm this hypothesis.

Macrophage-tumor cell associations: a factor in metastasis of breast cancer?

In human breast carcinomas tumor cells and macrophages are often proximal. We previously reported on the relationship between tumor cell growth and macrophage concentration and report here on the possible involvement of macrophages in the metastatic process. We hypothesize that during the initial stages of metastasis, tumor cells are likely to encounter macrophages and form aggregates. Using a cell culture method that encourages cellular interactions, we found aggregates involving macrophages. Macrophages partly or completely surround other cell types without any apparent ill effect. Units involving macrophages and tumor cells would possess many properties necessary for invasion, which is a normal process for macrophages. Properties such as motility and production of specific enzymes necessary to traverse the extracellular matrix, basement membrane, and endothelial cell barriers may provide an advantage for tumor cells. Physical support and protection from immune recognition during transport of the tumor cell through the vascular system may also be enhanced, and paracrine growth stimulation and angiogenic activity may be provided at the new metastatic site. Verification of these observations in vivo could lead to new directions for limiting breast cancer metastasis.

An apparatus to retain the spatial orientation of breast biopsies

An apparatus has been designed to retain the spatial orientation of breast biopsies throughout surgery, transport and processing in the pathology laboratory. It does not interfere with regular surgical procedures and simplifies the surgeon's task of marking the orientation of a specimen. As the use of the apparatus does not involve either chemical or physical substances it is an appropriate handling procedure for those specimens requiring sensitive testing procedures such as cell culture.

Estrogen receptor distribution in the peripheral, intermediate and central regions of breast cancers

The central, intermediate and peripheral regions of 25 breast tumors were analyzed for estrogen receptors (ER) using a combined biochemical (BC)/immunohistochemical (IHC) micromethod. To optimize the regional comparison, the percentage carcinoma per sample (PCS) was evaluated and incorporated into the quantification of the ER. Correction of the measured ER for the PCS eliminated differences in receptor levels between the central and peripheral regions but not the intermediate region. Although the corrected BC-ER level in this region was found to be about 20% higher, the IHC method did not detect such a difference. Determination of the ER status at the actual growth front of a tumor, rather than in the intermediate region where ER levels appear to be highest, may be of greater clinical relevance. Intra-regional ER heterogeneity appears, however, to be particularly pronounced in this area of a tumor.

Concerted contractions of tumour fragments derived from a pure mucoid carcinoma of the breast in vitro

Organized tissue fragments obtained by dissociation of a pure mucoid carcinoma of the breast were cultured in vitro. The cellular organization of the fragments appears similar to that observed in vivo, and consist of mucous-filled spherules surrounded by a single layer of tumour cells. Time-lapse video recordings revealed that the cells surrounding these fragments undergo a concerted contraction and relaxation over the time span of several hours. The presence of cytokeratin and oestrogen receptors in the cells suggests an epithelial derivation. Movement of tumour fragments of the type described here could potentially influence the metastatic process of some breast cancers.

Multiple microsample analysis of intratumor estrogen receptor distribution in breast cancers by a combined biochemical/immunohistochemical method

A multiple microsample analysis of estrogen receptors (ER) was performed on 81 samples obtained from 21 human breast cancers using a biochemical (BC) and immunohistochemical (IHC) method. Qualitative agreement occurred in 96% of the cases. Using both the percentage of cells staining specifically for ER as well as the intensity of staining (Histoscore) a semiquantitative correlation between the two analyses was obtained. Large variations in cellularity and the percentage of cells that stained specifically for ER existed within individual tumors. In most cases the variation in intensity of staining was minimal. Both the level and distribution of ER in different areas of individual tumors were calculated using a correction for differences in cellularity amongst samples. Heterogeneity in ER level as well as distribution was found in some tumors. In addition, a "checkerboard" type of staining with intermixed ER positive and ER negative cells was observed. This combined BC/IHC method may provide specific information about intratumor ER heterogeneity not available from either method alone.

Heterogeneous estrogen receptor levels detected via multiple microsamples from individual breast cancers

Twenty-six surgical breast cancer specimens were subjected to multiple estrogen receptor (ER) assays with a microsample technique. In most tumors there were large variations in ER levels in samples taken from different regions of the same tumor. After correction of individual samples for differences in carcinoma content, such variations were not abolished. Nine of the 26 breast cancers, although positive overall, were devoid of ER in some regions. For ER-positive tumors the average coefficient of variation (CV) for intratumor ER levels was 86%, with a range from 25% to 200%. This is well above the CV obtained with repeat samples of homogeneous tissue (14%). These results suggest that many ER-positive cancers may be composed of cells with a variety of ER levels. An assessment of individual intratumor ER variability may have biologic and clinical significance.

Estrogen receptor assay on breast cancer microsamples: implications of percent carcinoma estimation

Forty-milligram strips of malignant breast tissue were divided longitudinally into 20-mg microsamples. Soluble protein concentration was determined for one-half, and histologic evaluation for viable carcinoma content was made on its sister half. The correlation coefficient for 88 such comparisons was 0.330. This suggests that estrogen receptor (ER) assays that do not take into account the actual amount of carcinoma present in the sample may not permit reliable stratification of ER data. Using this technique, ER values obtained for 129 breast tumor microsamples were adjusted to reflect carcinoma content. A comparison of ER values before and after such adjustment revealed that the relative status of 73% was not significantly changed. The ER status of 27%, however, was changed sufficiently to be of potential clinical significance.

Electrophoretic assay of specific estrogen receptors: a contribution to methodology

Experimental evidence is presented that supports the use of the cold agar-gel electrophoretic method for the clinical quantitation of specific estrogen-binding protein present in some human mammary carcinomas. It is necessary to dilute tumor extracts to avoid interference by serum-borne, non-relevant hormone-binding proteins such as albumin, which migrates to the same anodal region as does the binding protein. Dilution to 2.5 mg or less of total protein per milliliter circumvents such interference while still permitting reliable quantitation of the binding protein. Seventy-two mammary carcinomas were compared for binding-protein content by both the cold agar-gel electrophoresis and a single-point dextran-coated charcoal assay. The correlation coefficient (0.96) indicated excellent agreement between results by the two methods. In addition results are presented which indicate that the preparation of tumor extracts for electrophoresis does not require the use of an ultracentrifuge.

Electrophoretic assay of specific estrogen receptors: a contribution to methodology

Experimental evidence is presented that supports the use of the cold agar-gel electrophoretic method for the clinical quantitation of specific estrogen-binding protein present in some human mammary carcinomas. It is necessary to dilute tumor extracts to avoid interference by serum-borne, non-relevant hormone-binding proteins such as albumin, which migrates to the same anodal region as does the binding protein. Dilution to 2.5 mg or less of total protein per milliliter circumvents such interference while still permitting reliable quantitation of the binding protein. Seventy-two mammary carcinomas were compared for binding-protein content by both the cold agar-gel electrophoresis and a single-point dextran-coated charcoal assay. The correlation coefficient (0.96) indicated excellent agreement between results by the two methods. In addition results are presented which indicate that the preparation of tumor extracts for electrophoresis does not require the use of an ultracentrifuge.

A thin-layer gel filtration assay of cytoplasmic oestrogen receptors. A possible screening method for hormone dependent tumours

A thin-layer gel filtration system for the assay of oestrogen receptors in target organ tissue samples as small as 50 mg is presented and compared with the sucrose gradient centrifugation method. Only specific high-affinity binding of [(3)H]17β-oestradiol to endometrial cytosol has been observed with the thin-layer gel filtration assay, despite the presence of relatively high levels of nonspecific binding components. The system could be adapted to the clinical determination of oestrogen receptor content in biopsy material from mammary and endometrial tumours and would be of value in predicting hormone dependency.