Randomized Phase 3 trial demonstrating high efficacy, favourable safety and convenience of a novel calcipotriol and betamethasone dipropionate cream for the treatment of psoriasis.

BACKGROUND: The fixed dose combination of calcipotriene (CAL) and betamethasone dipropionate (BDP) is a well-established topical treatment option for psoriasis based on strong scientific rationale for the single agents having complementary efficacy and safety. CAL/BDP PAD-cream is an easily spreadable cream based on PAD Technology™, an innovative formulation and drug delivery system. OBJECTIVES AND METHODS: A Phase 3, multicentre, randomized, investigator-blind, active and vehicle-controlled trial enrolling 490 patients with mild to moderate psoriasis according to the Physician Global Assessment (PGA) scale was conducted in three European countries. Products were applied once daily for 8 weeks. The aim of the trial was to evaluate the efficacy and safety of CAL/BDP PAD-cream as well as treatment acceptability compared to CAL/BDP gel and PAD-cream vehicle. Primary endpoint was percentage change in modified Psoriasis Area and Severity Index (mPASI) from baseline to Week 8. RESULTS: The percentage mean change from baseline to Week 8 in mPASI for CAL/BDP PAD-cream (67.5%) was superior compared to PAD-cream vehicle (11.7%; p < 0.0001) and non-inferior to CAL/BDP gel (63.5%). The proportion of patients achieving PGA treatment success (at least two-step improvement to clear or almost clear) after 8 weeks was superior for CAL/BDP PAD-cream (50.7%) compared to PAD-cream vehicle (6.1%, p < 0.0001) and statistically significantly greater than CAL/BDP gel (42.7%, p = 0.0442). Patient-reported psoriasis treatment convenience score (PTCS) for CAL/BDP PAD-cream was rated superior to CAL/BDP gel at Week 8 (p < 0.0001) and the mean change in DLQI from baseline to Week 8 improved statistically significantly more in the CAL/BDP PAD-cream group compared to both PAD-cream vehicle (p < 0.0001) and CAL/BDP gel (p = 0.0110). Safety assessments during the trial demonstrated that CAL/BDP PAD-cream was well-tolerated. CONCLUSION: CAL/BDP PAD-cream is a novel topical treatment of psoriasis that has a high efficacy and a favourable safety profile combined with a superior patient-reported treatment convenience.

Osteoporosis identification among previously undiagnosed individuals with vertebral fractures.

Because osteoporosis is under-recognized in patients with vertebral fractures, we evaluated characteristics associated with osteoporosis identification. Most patients with vertebral fractures did not receive evaluation or treatment for osteoporosis. Black, younger, and male participants were particularly unlikely to have had recognized osteoporosis, which could increase their risk of negative outcomes. INTRODUCTION: Vertebral fractures may be identified on imaging but fail to prompt evaluation for osteoporosis. Our objective was to evaluate characteristics associated with clinical osteoporosis recognition in patients who had vertebral fractures detected on their thoracolumbar spine imaging reports. METHODS: We prospectively identified individuals who received imaging of the lower spine at primary care clinics in 4 large healthcare systems who were eligible for osteoporosis screening and lacked indications of osteoporosis diagnoses or treatments in the prior year. We evaluated characteristics of participants with identified vertebral fractures that were associated with recognition of osteoporosis (diagnosis code in the health record; receipt of bone mineral density scans; and/or prescriptions for anti-osteoporotic medications). We used mixed models to estimate adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs). RESULTS: A total of 114,005 participants (47% female; mean age 65 (interquartile range: 57-72) years) were evaluated. Of the 8579 (7%) participants with vertebral fractures identified, 3784 (44%) had recognition of osteoporosis within the subsequent year. In adjusted regressions, Black participants (OR (95% CI): 0.74 (0.57, 0.97)), younger participants (age 50-60: 0.48 (0.42, 0.54); age 61-64: 0.70 (0.60, 0.81)), and males (0.39 (0.35, 0.43)) were less likely to have recognized osteoporosis compared to white participants, adults aged 65 + years, or females. CONCLUSION: Individuals with identified vertebral fractures commonly did not have recognition of osteoporosis within a year, particularly those who were younger, Black, or male. Providers and healthcare systems should consider efforts to improve evaluation of osteoporosis in patients with vertebral fractures.

A pooled analysis of randomized, controlled, phase 3 trials investigating the efficacy and safety of a novel, fixed dose calcipotriene and betamethasone dipropionate cream for the topical treatment of plaque psoriasis.

BACKGROUND: Plaque psoriasis is a common, chronic and relapsing inflammatory skin disease clinically characterized by erythema and scaling desquamation. As over 90% of psoriasis patients benefit from topical therapies, local treatments continue to play an eminent role in management strategies. One such topical treatment is the fixed dose combination of calcipotriol (CAL) and betamethasone dipropionate (BDP). OBJECTIVES: Pooled analysis of two different phase 3 clinical trails to compare superiority regarding efficacy, safety and quality of life (QoL) between CAL/BDP PAD-cream and CAL/BDP TS. METHODS: The data from two phase 3, multicentre, randomized, investigator-blind, active and vehicle-controlled trials enrolling patients with psoriasis were pooled and analysed. Investigational products included a CAL/BDP cream based on PAD™ Technology (PAD-cream) designed for high skin penetration and increased patient preference, an active control (marketed CAL/BDP topical suspension/gel, in the following abbreviated as CAL/BDP TS) and cream vehicle, which were applied once daily for 8 weeks. RESULTS: Efficacy and safety of the novel CAL/BDP PAD-cream formulation for the topical treatment of psoriasis demonstrated superiority for all efficacy end points after 8 weeks of treatment. PGA treatment success for CAL/BDP PAD-cream (43.2%) was greater than CAL/BDP TS (31.9%; P < 0.0001), the mean per cent reduction in mPASI for CAL/BDP PAD-cream was 64.6% compared to 56.4% for CAL/BDP TS (P < 0.0001) and DLQI 0/1 was obtained by 43.8% in the CAL/BDP PAD-cream group versus 34.2% in the CAL/BDP TS group (P = 0.0005). There was no adverse drug reaction reported with a frequency of >1%, associated with the CAL/BDP PAD-cream. CONCLUSIONS: The novel fixed dose combination CAL/BDP PAD-cream offers greater efficacy, superior patient QoL and equivalent favourable safety for the topical treatment of psoriasis, in comparison to the currently available topical suspension/gel.

Ivermectin 1% cream for rosacea.

The etiology of papulopustular rosacea (PPR) is not well understood yet appears to involve both the innate and adaptive immune response in addition to possible infestation with Demodex mites. Current treatments for PPR consist mainly of antibiotics. Ivermectin cream 1%, a new topical treatment for PPR, possesses both anti-inflammatory and anti-parasitic properties. After 12 weeks of treatment, subjects treated with ivermectin cream 1% had significantly greater reductions in PPR symptoms and enhanced diseaserelated quality of life improvements compared to subjects who received vehicle. Furthermore, PPR symptoms continued to improve with prolonged treatment (40 weeks). Ivermectin cream 1% offers a multi-pronged approach to combat the complex pathophysiology of rosacea.

Level of asthma control and healthcare utilization in Latin America.

The purpose of this study was to investigate whether uncontrolled asthma was associated with healthcare outcomes among Latin American patients with asthma. We used data from 2168 patients with asthma who participated in the 2011 Latin America Asthma Insights and Management (AIM) survey. Using Global Initiative for Asthma (GINA) guidelines, patients were categorized as having asthma that was well-controlled, partly controlled, or uncontrolled. Overall, 7% of the patients surveyed had asthma that was classified as well-controlled. Patients whose asthma was not well-controlled were significantly more likely to report use of asthma medications (ORs ranging from 1.6-41) and to have had emergency healthcare visits or hospitalizations for their asthma in the previous year (ORs ranging from 2.1 to 5.9). They also reported decreases in their productivity compared to patients with well-controlled asthma. These associations suggest that emphasis on improving asthma control could have substantial effects on patient productivity and utilization of healthcare resources.

Ranking possible carcinogenic hazards.

This review discusses reasons why animal cancer tests cannot be used to predict absolute human risks. Such tests, however, may be used to indicate that some chemicals might be of greater concern than others. Possible hazards to humans from a variety of rodent carcinogens are ranked by an index that relates the potency of each carcinogen in rodents to the exposure in humans. This ranking suggests that carcinogenic hazards from current levels of pesticide residues or water pollution are likely to be of minimal concern relative to the background levels of natural substances, though one cannot say whether these natural exposures are likely to be of major or minor importance.

Rodent carcinogens: setting priorities.

The human diet contains an enormous background of natural chemicals, such as plant pesticides and the products of cooking, that have not been a focus of carcinogenicity testing. A broadened perspective that includes these natural chemicals is necessary. A comparison of possible hazards for 80 daily exposures to rodent carcinogens from a variety of sources is presented, using an index (HERP) that relates human exposure to carcinogenic potency in rodents. A similar ordering would be expected with the use of standard risk assessment methodology for the same human exposure values. Results indicate that, when viewed against the large background of naturally occurring carcinogens in typical portions of common foods, the residues of synthetic pesticides or environmental pollutants rank low. A similar result is obtained in a separate comparison of 32 average daily exposures to natural pesticides and synthetic pesticide residues in the diet. Although the findings do not indicate that these natural dietary carcinogens are important in human cancer, they cast doubt on the relative importance for human cancer of low-dose exposures to synthetic chemicals.

Reproducibility of results in "near-replicate" carcinogenesis bioassays.

Reproducibility of results was examined in 70 "near-replicate" comparisons consisting of 2 or more long-term carcinogenesis bioassays of the same chemical administered by the same route and using the same sex and strain of rodent. Overall, there was good reproducibility of positivity, target site, and carcinogenic potency in hamsters, mice, and rats. The published authors' opinions about whether the test was positive disagreed in only 9 of the 70 comparisons. Among the 35 comparisons in which all tests of the chemical were positive, 33 of the near-replicates had at least 1 identical target site. The carcinogenic potency values estimated from near-replicate tests in these 35 comparisons were within a factor of 2 of each other in 40% of the comparisons, within a factor of 5 in 80%, and within a factor of 10 in 90%. For the few cases in which the carcinogenic response was not reproduced, analyses suggest two explanations: In mice the discrepant cases tended to have shorter experiment times than average; in both rats and mice the discrepant results tended to be tests of weakly active compounds.

Animal cancer tests and cancer prevention.

The toxicological significance of exposures to synthetic chemicals is examined in the context of exposures to naturally occurring chemicals. We calculate that 99.99% (by weight) of the pesticides in the US diet are chemicals that plants produce to defend themselves (nature's pesticides). Only 52 of these natural pesticides have been tested in high-dose animal cancer tests, and 27 are rodent carcinogens; these 27 are shown to be present in many common foods. The toxicology of synthetic chemicals is compared to that of natural chemicals, which represent the vast bulk of the chemicals to which humans are exposed. It is argued that animals have a broad array of inducible general defenses to combat the changing array of toxic chemicals in plant food and that these defenses are effective against both natural and synthetic toxins. Synthetic toxins (eg, dioxin) are compared to natural chemicals (eg, indole carbinol [in broccoli] and ethanol). The finding that, in high-dose tests, a high proportion of both natural and synthetic chemicals are carcinogens, mutagens, teratogens, and clastogens (30%-50% for each group) calls into question current efforts to use these tests to protect public health by regulating low doses of synthetic chemicals. The administration of chemicals at the maximum tolerated dose in standard animal cancer tests is postulated to increase cell division (mitogenesis), which in turn increases rates of mutagenesis and, thus, carcinogenesis. The animal data are consistent with this mechanism, because a high proportion--about 50%--of all chemicals tested (whether natural or synthetic) are indeed rodent carcinogens.(ABSTRACT TRUNCATED AT 250 WORDS)

Heterocyclic amines formed by cooking food: comparison of bioassay results with other chemicals in the Carcinogenic Potency Database.

Results in the Carcinogenic Potency Database (CPDB) on 11 mutagenic heterocyclic amines (HA) tested for carcinogenicity in rats, mice and cynomolgus monkeys are compared to results for other chemicals. An analysis of strength of evidence of carcinogenicity for HA vs. other mutagenic carcinogens and vs. all rodent carcinogens, indicates strong carcinogenicity of HA in terms of positivity rates and multiplicity of target sites. The liver is the most frequent target site in each species. Despite several target sites in each species, concordance in target sites between rats and mice is restricted to the liver for each HA except one. In cynomolgus monkeys, liver tumors have been induced rapidly by 2-amino-3-methylimidazo[4,5-f]quinoline (IQ). Human exposures to HA in cooked animal foods are small, in the low ppb range. A comparison of possible carcinogenic hazards from a variety of exposures to rodent carcinogens in the American diet is presented, using an index (Human Exposure/Rodent Potency, HERP) that relates human exposure to carcinogenic potency in rodents. Results indicate that there is a large background of exposures to naturally-occurring rodent carcinogens in typical portions of common foods, and that possible hazards from HA rank below those of most natural pesticides and products of cooking or food preparation; synthetic pesticide residues also rank low.

The causes and prevention of cancer: gaining perspective.

Epidemiological studies have identified several factors that are likely to have a major effect on reducing rates of cancer: reduction of smoking, increased consumption of fruits and vegetables, and control of infections. Other factors include avoidance of intense sun exposure, increased physical activity, and reduced consumption of alcohol and possibly red meat. Risks of many types of cancer can already be reduced, and the potential for further reductions is great. In the United States, cancer death rates for all cancers combined are decreasing, if lung cancer (90% of which is due to smoking), is excluded from the analysis. We review the research on causes of cancer and show why much cancer is preventable. The idea that traces of synthetic chemicals, such as DDT, are major contributors to human cancer is not supported by the evidence, yet public concern and resource allocation for reduction of chemical pollution are very high, in part because standard risk assessment uses linear extrapolation from limited data in high-dose animal cancer tests. These tests are done at the maximum tolerated dose (MTD) and are typically misinterpreted to mean that low doses of synthetic chemicals and industrial pollutants are relevant to human cancer. About half the chemicals tested, whether synthetic or natural, are carcinogenic to rodents at such high doses. Almost all chemicals in the human diet are natural. For example, 99.99% of the pesticides we eat are naturally present in plants to ward off insects and other predators. Half of the natural pesticides that have been tested at the MTD are rodent carcinogens. Cooking food produces large numbers of natural dietary chemicals. Roasted coffee, for example, contains more than 1000 chemicals: of 27 tested, 19 are rodent carcinogens. Increasing evidence supports the idea that the high frequency of positive results in rodent bioassays is due to testing at the MTD, which frequently can cause chronic cell killing and consequent cell replacement-a risk factor for cancer that can be limited to high doses. Because default risk assessments use linear extrapolation, which ignores effects of the high dose itself, low-dose risks are often exaggerated.

Summary of carcinogenic potency and positivity for 492 rodent carcinogens in the carcinogenic potency database.

A tabulation of carcinogenic potency (TD50) by species for 492 chemicals that induce tumors in rats or mice is presented. With the use of the Carcinogenic Potency Database, experimental results are summarized by indicating in which sex-species groups the chemical was tested and the respective evaluations of carcinogenicity. A comparison of three summary measures of TD50 for chemicals with more than one positive experiment per species shows that the most potent TD50 value is similar to measures that average values or functions of values. This tabulation can be used to investigate associations between rodent potency and other factors such as mutagenicity, teratogenicity, chemical structure, and human exposure.

DNA lesions, inducible DNA repair, and cell division: three key factors in mutagenesis and carcinogenesis.

DNA lesions that escape repair have a certain probability of giving rise to mutations when the cell divides. Endogenous DNA damage is high: 10(6) oxidative lesions are present per rat cell. An exogenous mutagen produces an increment in lesions over the background rate of endogenous lesions. The effectiveness of a particular lesion depends on whether it is excised by a DNA repair system and the probability that it gives rise to a mutation when the cell divides. When the cell divides, an unrepaired DNA lesion has a certain probability of giving rise to a mutation. Thus, an important factor in the mutagenic effect of an exogenous agent whether it is genotoxic or non-genotoxic, is the increment it causes over the background cell division rate (mitogenesis) in cells that appear to matter most in cancer, the stem cells, which are not on their way to being discarded. Increasing their cell division rate increases mutation and therefore cancer. There is little cancer from nondividing cells. Endogenous cell division rates can be influenced by hormone levels, decreased by calorie restriction, or increased by high doses of chemicals. If both the rate of DNA lesions and cell division are increased, then there will be a multiplicative effect on mutagenesis (and carcinogenesis), for example, by high doses of a mutagen that also increases mitogenesis through cell killing. The defense system against reactive electrophilic mutagens, such as the glutathione transferases, are also almost all inducible and buffer cells against increments in active forms of chemicals that can cause DNA lesions. A variety of DNA repair defense systems, almost all inducible, buffer the cell against any increment in DNA lesions. Therefore, the effect of a particular chemical insult depends on the level of each defense, which in turn depends on the past history of exposure. Exogenous agents can influence the induction and effectiveness of these defenses. Defenses can be partially disabled by lack of particular micronutrients in the diet (e.g., antioxidants).

Ranking the potential carcinogenic hazards to workers from exposures to chemicals that are tumorigenic in rodents.

For 41 chemicals there exist both reasonable data on carcinogenic potency in experimental animals and also a defined Permissible Exposure Level (PEL), which is the upper limit of legally permissible chronic occupational exposure for U.S. workers. These 41 agents are ranked by an index that compares the permitted chronic human exposure to the chronic dose rate that induces tumors in 50% of laboratory animals. This index, the Permitted Exposure/Rodent Potency index, or PERP, does not estimate absolute risks directly, but rather suggests the relative hazards that such substances may pose. The PERP values for these 41 substances differ by more than 100,000-fold from each other. The PERP does not take into account the actual level of exposure or the number of exposed workers. Nevertheless, it might be reasonable to give priority attention to the reduction of allowable worker exposures to substances that appear most hazardous by this index and that some workers may be exposed to full-time near the PEL. Ranked by PERP, these chemicals are: ethylene dibromide, ethylene dichloride, 1,3-butadiene, tetrachloroethylene, propylene oxide, chloroform, formaldehyde, methylene chloride, dioxane, and benzene.

Supplement to the Carcinogenic Potency Database (CPDB): results of animal bioassays published in the general literature in 1993 to 1994 and by the National Toxicology Program in 1995 to 1996.

The Carcinogenic Potency Database (CPDB) is a systematic and unifying analysis of results of chronic, long-term cancer tests. This paper presents a supplemental plot of the CPDB, including 513 experiments on 157 test compounds published in the general literature in 1993 and 1994 and in Technical Reports of the National Toxicology Program in 1995 and 1996. The plot standardizes the experimental results (whether positive or negative for carcinogenicity), including qualitative data on strain, sex, route of compound administration, target organ, histopathology, and author's opinion and reference to the published paper, as well as quantitative data on carcinogenic potency, statistical significance, tumor incidence, dose-response curve shape, length of experiment, duration of dosing, and dose rate. A numerical description of carcinogenic potency, the TD(subscript)50(/subscript), is estimated for each set of tumor incidence data reported. When added to the data published earlier, the CPDB now includes results of 5,620 experiments on 1,372 chemicals that have been reported in 1,250 published papers and 414 National Cancer Institute/National Toxicology Program Technical Reports. The plot presented here includes detailed analyses of 25 chemicals tested in monkeys for up to 32 years by the National Cancer Institute. Half the rodent carcinogens that were tested in monkeys were not carcinogenic, despite usually strong evidence of carcinogenicity in rodents and/or humans. Our analysis of possible explanatory factors indicates that this result is due in part to the fact that the monkey studies lacked power to detect an effect compared to standard rodent bioassays. Factors that contributed to the lack of power are the small number of animals on test; a stop-exposure protocol for model rodent carcinogens; in a few cases, toxic doses that resulted in stoppage of dosing or termination of the experiment; and in a few cases, low doses administered to monkeys or early termination of the experiment even though the doses were not toxic. Among chemicals carcinogenic in both monkeys and rodents, there is some support for target site concordance, but it is primarily restricted to liver tumors. Potency values are highly correlated between rodents and monkeys. The plot in this paper can be used in conjunction with the earlier results published in the CRC Handbook of Carcinogenic Potency and Genotoxicity Databases [Gold LS, Zeiger E, eds. Boca Raton FL:CRC Press, 1997] and with our web site (http://potency.berkeley.edu), which includes a guide to the plot of the database, a complete description of the numerical index of carcinogenic potency (TD50), and a discussion of the sources of data, the rationale for the inclusion of particular experiments and particular target sites, and the conventions adopted in summarizing the literature. Two summary tables permit easy access to the literature of animal cancer tests by target organ and by chemical. For readers using the CPDB extensively, a combined plot on diskette or other format is available from the first author. It includes all results published earlier and in this paper, ordered alphabetically by chemical. A SAS database is also available.

Target organs in chronic bioassays of 533 chemical carcinogens.

A compendium of carcinogenesis bioassay results organized by target organ is presented for 533 chemicals that are carcinogenic in at least one species. This compendium is based primarily on experiments in rats or mice; results in hamsters, nonhuman primates, and dogs are also reported. The compendium can be used to identify chemicals that induce tumors at particular sites, and to determine whether target sites are the same for chemicals positive in more than one species. The Carcinogenic Potency Database (CPDB), which includes results of 3969 experiments, is used in the analysis. The published CPDB includes details on each test, and literature references. Chemical carcinogens are reported for 35 different target organs in rats or mice. More than 80% of the carcinogens in each of these species are positive in at least one of the 8 most frequent target sites: liver, lung, mammary gland, stomach, vascular system, kidney, hematopoietic system, and urinary bladder. An analysis is presented of how well one can predict the carcinogenic response in mice from results in rats, or vice versa. Among chemicals tested in both species, 76% of rat carcinogens are positive in mice, and 71% of mouse carcinogens are positive in rats. Prediction is less accurate to the same target site: 52% of rat carcinogens are positive in the same site in mice, and 48% of mouse carcinogens are positive in the same site in rats. The liver is the most frequent site in common between rats and mice.

Interspecies extrapolation in carcinogenesis: prediction between rats and mice.

Interspecies extrapolation in carcinogenesis is studied by evaluating prediction from rats to mice and from mice to rats. The Carcinogenic Potency Database, which includes 3500 cancer tests conducted in rats or mice on 955 compounds, is used for the analysis. About half of the chemicals tested for carcinogenicity are positive in at least one test, and this proportion is similar when rats and mice are considered separately. For 392 chemicals tested in both species, 76% of the rat carcinogens are positive in the mouse, and 70% of mouse carcinogens are positive in the rat. When compounds composed solely of chlorine, carbon, hydrogen, and, optionally, oxygen are excluded from the analysis, 75% of mouse carcinogens are positive in the rat. Overall concordance (the percentage positive in both species plus the percentage negative in both) is 76%. Three factors that affect prediction between rats and mice are discussed: chemical class, mutagenicity in the Salmonella assay, and the dose level at which a chemical is toxic. Prediction is more accurate for mutagens than non-mutagens and for substances that are toxic at low (versus only at high) doses. Species differences are not the result of failure in the bioassay to attain the maximum tolerated dose in the negative species or of more frequent testing in the positive species. An analysis of the predictive value of positivity for the 10 most common target sites indicates that most sites are good predictors of carcinogenicity at some site in the other species; the poorest predictors among these common sites are the rat urinary bladder and the mouse liver.

The TD50: a proposed general convention for the numerical description of the carcinogenic potency of chemicals in chronic-exposure animal experiments.

A generally accepted format for the numerical description of the carcinogenic potency of a particular chemical in a particular strain of animals is desirable so that statements from different sources about potency and attempts by different authors to correlate potency with particular laboratory measurements will be comparable. The choice of an appropriate standard format is to a certain extent arbitrary. In this paper we recommend that the TD50 (tumorigenic dose rate 50) be used. TD50 can be calculated for a single target site or combination of sites. The TD50, in analogy with the LD50, is defined as that chronic dose rate (in mg/kg body weight/day) which would halve the actuarially adjusted percentage of tumor-free animals at the end of a standard experiment time--the "standard lifespan" for the species. This paper consists of a brief discussion of the TD50, sufficient to make the general reader familiar with the properties of such an index, an appendix discussing methods for its estimation and certain conventions we have adopted for use in analyzing "nonstandard" experiments. A major problem in calculating any index of carcinogenic potency is that much published material gives only the final crude percentage of tumor-bearing animals at each dose, instead of percentages adjusted for the effects of intercurrent mortality or data from which these adjusted percentages can be derived. If the dose level administered to the animals is toxic, then premature death from nonneoplastic causes may prevent some dosed animals that would have developed tumors from actually doing so. This will particularly affect the high-dose group.(ABSTRACT TRUNCATED AT 250 WORDS)

The Carcinogenic Potency Database: analyses of 4000 chronic animal cancer experiments published in the general literature and by the U.S. National Cancer Institute/National Toxicology Program.

The Carcinogenic Potency Database (CPDB) is an easily accessible, standardized resource of positive and negative long-term animal cancer tests. The CPDB has been published in four earlier papers that include results for approximately 4000 experiments on 1050 chemicals. This paper describes the CPDB: goals, inclusion criteria, fields of information, and published plot format. It also presents an overview of our published papers using the CPDB. The CPDB as published in plot format readily permits comparisons of carcinogenic potency and many other aspects of cancer tests, including for each experiment the species and strain of test animals, the route and duration of compound administration, dose level and other aspects of experimental protocol, histopathology and tumor incidence, TD50 (carcinogenic potency) and its statistical significance, dose response, author's opinion about carcinogenicity, and literature citation. A combined plot of all results from the four separate papers, which is ordered alphabetically by chemical, is available from L. S. Gold, in printed form or on computer tape or diskette. A computer readable (SAS) database is also available. The overview of papers includes descriptions of work on methods of estimating carcinogenic potency, reproducibility of results in near-replicate cancer tests, correlation in potency between species, ranking possible carcinogenic hazards, comparison of positivity and target organ in rats and mice, comparison of mutagens and nonmutagens, proportion of chemicals positive in animal tests, natural compared to synthetic chemicals, and mechanistic issues in interspecies extrapolation.