C-reactive protein and risk of lung cancer

C-reactive protein, interleukin 6 and lung cancer risk: a meta-analysis

PURPOSE

Epidemiologic findings are inconsistent concerning the associations between C-reactive protein (CRP), interleukin 6 (IL-6) and lung cancer risk. We conducted a meta-analysis of epidemiologic studies to examine these associations.

METHODS

A systematic literature search up to October 2011 was performed in MEDLINE and EMBASE. Study-specific risk estimates were pooled using a random-effects model.

RESULTS

The 10 studies on CRP involved a total of 1918 lung cancer cases. The pooled RR of lung cancer for one unit change in natural logarithm (ln) CRP was 1.28 (95% CI 1.17-1.41). There was no statistically significant heterogeneity among studies (P = 0.116; I(2) = 36.6%). We also found that CRP was significantly associated with increased risk of lung cancer among men (RR 1.18, 95% CI 1.09-1.28) but not among women. The 5 studies on IL-6 involved a total of 924 lung cancer cases. The pooled RR of lung cancer for one unit change in ln IL-6 was 1.28 (95% CI 0.92-1.79), however, statistically significant heterogeneity was found. After excluding the study contributing most to the heterogeneity, the summary estimate was essentially unchanged.

CONCLUSION

CRP was associated with increased risk of lung cancer, especially among men. There was no significant association between IL-6 and lung cancer risk.

Chapter 6: Lung cancer in never smokers: epidemiology and risk prediction models

In this chapter we review the epidemiology of lung cancer incidence and mortality among never smokers/nonsmokers and describe the never smoker lung cancer risk models used by the Cancer Intervention and Surveillance Network (CISNET) modelers. Our review focuses on those influences likely to have measurable population impact on never smoker risk, such as secondhand smoke, even though the individual-level impact may be small. Occupational exposures may also contribute importantly to the population attributable risk of lung cancer. We examine the following risk factors in this chapter: age, environmental tobacco smoke, cooking fumes, ionizing radiation including radon gas, inherited genetic susceptibility, selected occupational exposures, preexisting lung disease, and oncogenic viruses. We also compare the prevalence of never smokers between the three CISNET smoking scenarios and present the corresponding lung cancer mortality estimates among never smokers as predicted by a typical CISNET model.

Multistage analysis of variants in the inflammation pathway and lung cancer risk in smokers

BACKGROUND

Tobacco-induced lung cancer is characterized by a deregulated inflammatory microenvironment. Variants in multiple genes in inflammation pathways may contribute to risk of lung cancer.

METHODS

We therefore conducted a three-stage comprehensive pathway analysis (discovery, replication, and meta-analysis) of inflammation gene variants in ever-smoking lung cancer cases and controls. A discovery set (1,096 cases and 727 controls) and an independent and nonoverlapping internal replication set (1,154 cases and 1,137 controls) were derived from an ongoing case-control study. For discovery, we used an iSelect BeadChip to interrogate a comprehensive panel of 11,737 inflammation pathway single-nucleotide polymorphisms (SNP) and selected nominally significant (P < 0.05) SNPs for internal replication.

RESULTS

There were six SNPs that achieved statistical significance (P < 0.05) in the internal replication data set with concordant risk estimates for former smokers and five concordant and replicated SNPs in current smokers. Replicated hits were further tested in a subsequent meta-analysis using external data derived from two published genome-wide association studies (GWAS) and a case-control study. Two of these variants (a BCL2L14 SNP in former smokers and an SNP in IL2RB in current smokers) were further validated. In risk score analyses, there was a 26% increase in risk with each additional adverse allele when we combined the genotyped SNP and the most significant imputed SNP in IL2RB in current smokers and a 36% similar increase in risk for former smokers associated with genotyped and imputed BCL2L14 SNPs. CONCLUSIONS/IMPACT: Before they can be applied for risk prediction efforts, these SNPs should be subject to further external replication and more extensive fine mapping studies.

Neutralization of tumor necrosis factor bioactivity ameliorates urethane-induced pulmonary oncogenesis in mice

Tumor necrosis factor (TNF) has been implicated in inflammation-associated tumor progression. Although multiple reports identified a role for TNF signaling in established cancers, few studies have assessed the impact of TNF blockade on early tumor formation promotion. We aimed at exploring the effects of TNF neutralization in a preclinical mouse model of lung carcinogenesis. For this, Balb/c mice (n = 42) received four weekly intraperitoneal urethane injections (1 g/kg) and twice-weekly intraperitoneal soluble TNF receptor (etanercept; 10 mg/kg) administered during tumor initiation/promotion, tumor progression, or continuously (months 1, 6, and 1-8 after urethane start, respectively). Lung oncogenesis was assessed after 8 months. In separate short-term studies, Balb/c mice (n = 21) received a single control or urethane injection followed by twice-weekly intraperitoneal control or sTNFR:Fc injections. Lung inflammation was assessed after 1 week. We found that sTNFR:Fc treatment during tumor initiation/promotion resulted in a significant reduction of tumor number but not dimensions. However, sTNFR:Fc administered during tumor progression did not impact tumor multiplicity but significantly decreased tumor diameter. Continued sTNFR:Fc administration was effective in halting both respiratory tumor formation and progression in response to urethane. This favorable impact was associated with impaired cellular proliferation and new vessel formation in lung tumors. In addition, TNF neutralization altered the lung inflammatory response to urethane, evidenced by reductions in TNF and macrophage and increases in interferon γ and interleukin 10 content of the air spaces. sTNFR:Fc treatment of RAW264.7 macrophages downregulated TNF and enhanced interferon γ and interleukin 10 expression. In conclusion, TNF neutralization is effective against urethane-induced lung oncogenesis in mice and could present a lung chemoprevention strategy worth testing clinically.

[COPD and lung cancer: epidemiological and biological links]

Lung cancer and chronic obstructive lung disease (COPD) are two common fatal diseases. Apart from their common link to tobacco, these two diseases are usually considered to be the result of separate distinct mechanisms. In the past 15 years, numerous studies have produced arguments in favour of a relationship between these two pathologies that goes beyond a simple addition of risk factors. At the epidemiological level, there are data that demonstrate an increased incidence of bronchial carcinoma in patients with COPD. The links between these two pathologies are still unexplained but there are numerous arguments supporting a common physiopathology. Common genetic and epigenetic abnormalities, mechanical factors and signalisation pathways have been quoted. COPD and lung cancer appear to be two diseases possessing a genetic basis that creates a predisposition to environmental or toxic assaults, resulting in a different clinical manifestation in each disease. Consequently, improvements in the management of these two diseases will involve a more intensive investigation of their physiopathology, and require a closer collaboration between research centres and clinical units.

Helicobacter pylori seropositivity and risk of lung cancer

Lung cancer is the leading cause of cancer mortality worldwide. Helicobacter pylori (H. pylori) is a risk factor for distal stomach cancer, and a few small studies have suggested that H. pylori may be a potential risk factor for lung cancer. To test this hypothesis, we conducted a study of 350 lung adenocarcinoma cases, 350 squamous cell carcinoma cases, and 700 controls nested within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study (ATBC) cohort of male Finnish smokers. Controls were one-to-one matched by age and date of baseline serum draw. Using enzyme-linked immunosorbent assays to detect immunoglobulin G antibodies against H. pylori whole-cell and cytotoxin-associated gene (CagA) antigens, we calculated odds ratios (ORs) and 95% confidence intervals (95% CIs) for associations between H. pylori seropositivity and lung cancer risk using conditional logistic regression. H. pylori seropositivity was detected in 79.7% of cases and 78.5% of controls. After adjusting for pack-years and cigarettes smoked per day, H. pylori seropositivity was not associated with either adenocarcinoma (OR: 1.1, 95% CI: 0.75–1.6) or squamous cell carcinoma (OR: 1.1, 95% CI: 0.77–1.7). Results were similar for CagA-negative and CagA-positive H. pylori seropositivity. Despite earlier small studies suggesting that H. pylori may contribute to lung carcinogenesis, H. pylori seropositivity does not appear to be associated with lung cancer.

Opposing effects of bortezomib-induced nuclear factor-κB inhibition on chemical lung carcinogenesis

Since recent evidence indicates a requirement for epithelial nuclear factor (NF)-κB signaling in lung tumorigenesis, we investigated the impact of the NF-κB inhibitor bortezomib on lung tumor promotion and growth. We used an experimental model in which wild-type mice or mice expressing an NF-κB reporter received intraperitoneal urethane (1 g/kg) followed by twice weekly bortezomib (1 mg/kg) during distinct periods of tumor initiation/progression. Mice were serially assessed for lung NF-κB activation, inflammation and carcinogenesis. Short-term proteasome inhibition with bortezomib did not impact tumor formation but retarded the growth of established lung tumors in mice via effects on cell proliferation. In contrast, long-term treatment with bortezomib resulted in significantly increased lung tumor number and size. This tumor-promoting effect of prolonged bortezomib treatment was associated with perpetuation of urethane-induced inflammation and chronic upregulation of interleukin-1β and proinflammatory C-X-C motif chemokine ligands (CXCL) 1 and 2 in the lungs. In addition to airway epithelium, bortezomib inhibited NF-κB in pulmonary macrophages in vivo, presenting a possible mechanism of tumor amplification. In this regard, RAW264.7 macrophages exposed to bortezomib showed increased expression of interleukin-1β, CXCL1 and CXCL2. In conclusion, although short-term bortezomib may exert some beneficial effects, prolonged NF-κB inhibition accelerates chemical lung carcinogenesis by perpetuating carcinogen-induced inflammation. Inhibition of NF-κB in pulmonary macrophages appears to play an important role in this adverse process.

Cancer risk by combined levels of YKL-40 and C-reactive protein in the general population

Background:

YKL-40 and C-reactive protein (CRP) are biomarkers that may reflect cancer-related subclinical inflammation. We assessed elevated YKL-40 and CRP levels as combined risk predictors for cancer.

Methods:

We measured plasma YKL-40 and CRP at baseline in 8706 individuals from the Danish general population.

Results:

Hazard ratio (HR) of gastrointestinal cancer for a doubling of YKL-40 levels was 1.37 (95% CI: 1.17–1.61) and indifferent to adjustment for CRP levels. Hazard ratio of lung cancer for a doubling of CRP levels was 1.35 (1.17–1.56) and indifferent to adjustment for YKL-40 levels. Compared to individuals with both low CRP (<1.7 mg l⁻¹) and YKL-40 (<154 μg l⁻¹), individuals with high YKL-40 but low CRP had an HR of gastrointestinal cancer of 3.36 (1.70–6.64), whereas individuals with high CRP but low YKL-40 had an HR of lung cancer of 2.19 (1.24–3.87). The area under the receiver operating characteristic (ROC) curve was 0.68 for the ability of YKL-40 to predict gastrointestinal cancer and 0.67 for the ability of CRP to predict lung cancer.

Conclusion:

Elevated YKL-40 levels are associated with increased risk of gastrointestinal cancer, independently of CRP levels, whereas elevated CRP levels are associated with increased risk of lung cancer, independently of YKL-40 levels.

Lung cancer chemoprevention with celecoxib in former smokers

Ample studies suggest that the cyclooxygenase-2 (COX-2)/prostaglandin E(2) (PGE(2)) pathway plays a pivotal role in carcinogenesis and that COX-2 inhibition may help prevent lung cancer. Therefore, we conducted a randomized, double-blind, placebo-controlled trial of the COX-2-selective inhibitor celecoxib (400 mg bid for 6 months) in former-smokers (age ≥ 45, ≥ 30 pack-years of smoking, ≥ 1 year of sustained abstinence from smoking). We assessed the impact of celecoxib on cellular and molecular events associated with lung cancer pathogenesis; the primary endpoint was bronchial Ki-67 labeling index (Ki-67 LI) after 6 months of treatment. Of 137 randomized subjects, 101 completed both baseline and 6-month bronchoscopies and were evaluable for the primary endpoint analysis. The beneficial effect on Ki-67 LI was greater in the celecoxib arm (versus placebo) in a mixed-effects analysis (P = 0.0006), and celecoxib significantly decreased Ki-67 LI by an average of 34%, whereas placebo increased Ki-67 LI by an average of 3.8% (P = 0.04; t test). In participants who crossed over to the other study arm at 6 months (all of whom had received 6 months of celecoxib at the end of a 12 months treatment period), the decreases in Ki-67 LI correlated with a reduction and/or resolution of lung nodules on computed tomography. Celecoxib significantly reduced plasma c-reactive protein and interleukin-6 mRNA and protein and increased 15(S)-hydroxy-eicosatetraenoic acid levels in bronchoalveolar lavage (BAL) samples. The baseline ratio of COX-2 to 15-hydroxyprostaglandin dehydrogenase mRNA in BAL cells was a significant predictive marker of Ki-67 response to celecoxib (P = 0.002). Our collective findings support the continued investigation of celecoxib for lung cancer chemoprevention in former smokers at a low risk of cardiovascular disease.

Heat shock proteins as danger signals for cancer detection

First discovered in 1962, heat shock proteins (HSPs) are highly studied with about 35,500 publications on the subject to date. HSPs are highly conserved, function as molecular chaperones for a large panel of “client” proteins and have strong cytoprotective properties. Induced by many different stress signals, they promote cell survival in adverse conditions. Therefore, their roles have been investigated in several conditions and pathologies where HSPs accumulate, such as in cancer. Among the diverse mammalian HSPs, some members share several features that may qualify them as cancer biomarkers. This review focuses mainly on three inducible HSPs: HSP27, HPS70, and HSP90. Our survey of recent literature highlights some recurring weaknesses in studies of the HSPs, but also identifies findings that indicate that some HSPs have potential as cancer biomarkers for successful clinical applications.

Factors associated with inflammation markers, a cross-sectional analysis

Epidemiological studies have reported associations between circulating inflammation markers and risk of chronic diseases. It is of interest to examine whether risk factors for these diseases are associated with inflammation. We conducted a cross-sectional analysis to evaluate whether reproductive and lifestyle factors and circulating vitamin D were associated with inflammation markers, including C-reactive protein, cytokines (IL-1β, IL-2, IL-4, IL-5, IL-6, IL-10, IL-12p40, IL-12p70, IL-13, TNFα), and cytokine modulators (IL-1RA, sIL-1RII, sIL-2Ra, sIL-4R, sIL-6R, sTNF-R1/R2), among 616 healthy women. We confirmed associations of several inflammation markers with age and BMI. We also observed significantly higher levels of certain inflammation markers in postmenopausal vs. premenopausal women (TNFα, sIL-1RII, sIL-2Ra), with increasing parity (IL-12p40), and with higher circulating 25(OH) vitamin D (IL-13) and lower levels among current users of non-steroidal anti-inflammatory drugs (NSAIDs) (IL-1β, IL-2, IL-10, IL-12p70, and IL-12p40), current smokers (IL-4, IL-13, IL-12p40), and women with a family history of breast or ovarian cancer (IL-4, IL-10, IL-13). Our findings suggest that risk factors for chronic diseases (age, BMI, menopausal status, parity, NSAID use, family history of breast and ovarian cancer, and smoking) are associated with inflammation markers in healthy women.

Circulating markers of interstitial lung disease and subsequent risk of lung cancer

BACKGROUND

Inflammation and pulmonary diseases, including interstitial lung diseases, are associated with increased lung cancer risk. Circulating levels of surfactant protein-D (SP-D) and Krebs von Lungren-6 (KL-6) are elevated in interstitial lung disease patients and may be useful markers of processes contributing to lung cancer.

METHODS

We conducted a nested case-control study, including 532 lung cancer cases, 582 matched controls, and 150 additional controls with chest X-ray (CXR) evidence of pulmonary scarring, in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. Serum SP-D and KL-6 levels were measured using enzyme immunoassay. Logistic regression was used to estimate the associations of SP-D and KL-6 with lung cancer and CXR scarring.

RESULTS

Cases had higher levels than controls for SP-D (median 118.7 vs. 105.4 ng/mL, P = 0.008) and KL-6 (372.0 vs. 325.8 μg/mL, P = 0.001). Lung cancer risk increased with SP-D (P(trend) = 0.0003) and KL-6 levels (P(trend) = 0.005). Compared with the lowest quartile, lung cancer risk was elevated among those with the highest quartiles of SP-D (OR = 1.87, 95% CI: 1.32-2.64) or KL-6 (OR = 1.58, 95% CI: 1.11-2.25). Among controls, participants with CXR scarring were more likely than those without scarring to have elevated levels of SP-D (quartile 4 vs. quartile 1: OR = 1.67, 95% CI: 1.04-2.70, P(trend) = 0.05) but not of KL-6 (OR = 1.04, 95% CI: 0.64-1.68, P(trend) = 0.99).

CONCLUSION

Circulating levels of SP-D and KL-6 are associated with subsequent lung cancer risk.

IMPACT

Our findings support a potential role for interstitial lung disease in lung cancer etiology or early detection, but additional research is needed.

Early assessment of cancer outcomes in New York City firefighters after the 9/11 attacks: an observational cohort study

BACKGROUND

The attacks on the World Trade Center (WTC) on Sept 11, 2001 (9/11) created the potential for occupational exposure to known and suspected carcinogens. We examined cancer incidence and its potential association with exposure in the first 7 years after 9/11 in firefighters with health information before 9/11 and minimal loss to follow-up.

METHODS

We assessed 9853 men who were employed as firefighters on Jan 1, 1996. On and after 9/11, person-time for 8927 firefighters was classified as WTC-exposed; all person-time before 9/11, and person-time after 9/11 for 926 non-WTC-exposed firefighters, was classified as non-WTC exposed. Cancer cases were confirmed by matches with state tumour registries or through appropriate documentation. We estimated the ratio of incidence rates in WTC-exposed firefighters to non-exposed firefighters, adjusted for age, race and ethnic origin, and secular trends, with the US National Cancer Institute Surveillance Epidemiology and End Results (SEER) reference population. CIs were estimated with overdispersed Poisson models. Additional analyses included corrections for potential surveillance bias and modified cohort inclusion criteria.

FINDINGS

Compared with the general male population in the USA with a similar demographic mix, the standardised incidence ratios (SIRs) of the cancer incidence in WTC-exposed firefighters was 1·10 (95% CI 0·98-1·25). When compared with non-exposed firefighters, the SIR of cancer incidence in WTC-exposed firefighters was 1·19 (95% CI 0·96-1·47) corrected for possible surveillance bias and 1·32 (1·07-1·62) without correction for surveillance bias. Secondary analyses showed similar effect sizes.

INTERPRETATION

We reported a modest excess of cancer cases in the WTC-exposed cohort. We remain cautious in our interpretation of this finding because the time since 9/11 is short for cancer outcomes, and the reported excess of cancers is not limited to specific organ types. As in any observational study, we cannot rule out the possibility that effects in the exposed group might be due to unidentified confounders. Continued follow-up will be important and should include cancer screening and prevention strategies.

FUNDING

National Institute for Occupational Safety and Health.

Variants in inflammation genes are implicated in risk of lung cancer in never smokers exposed to second-hand smoke

Lung cancer in lifetime never smokers is distinct from that in smokers, but the role of separate or overlapping carcinogenic pathways has not been explored. We therefore evaluated a comprehensive panel of 11,737 single-nucleotide polymorphisms (SNP) in inflammatory-pathway genes in a discovery phase (451 lung cancer cases, 508 controls from Texas). SNPs that were significant were evaluated in a second external population (303 cases, 311 controls from the Mayo Clinic). An intronic SNP in the ACVR1B gene, rs12809597, was replicated with significance and restricted to those reporting adult exposure to environmental tobacco smoke. Another promising candidate was an SNP in NR4A1, although the replication OR did not achieve statistical significance. ACVR1B belongs to the TGFR-β superfamily, contributing to resolution of inflammation and initiation of airway remodeling. An inflammatory microenvironment (second-hand smoking, asthma, or hay fever) is necessary for risk from these gene variants to be expressed. These findings require further replication, followed by targeted resequencing, and functional validation.

Increased levels of circulating interleukin 6, interleukin 8, C-reactive protein, and risk of lung cancer

BACKGROUND

Previous studies that were based primarily on small numbers of patients suggested that certain circulating proinflammatory cytokines may be associated with lung cancer; however, large independent studies are lacking.

METHODS

Associations between serum interleukin 6 (IL-6) and interleukin 8 (IL-8) levels and lung cancer were analyzed among 270 case patients and 296 control subjects participating in the National Cancer Institute-Maryland (NCI-MD) case-control study. Results were validated in 532 case patients and 595 control subjects in a nested case-control study within the prospective Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial. Association with C-reactive protein (CRP), a systemic inflammation biomarker, was also analyzed. Associations between biomarkers and lung cancer were estimated using logistic regression models adjusted for smoking, stage, histology, age, and sex. The 10-year standardized absolute risks of lung cancer were estimated using a weighted Cox regression model.

RESULTS

Serum IL-6 and IL-8 levels in the highest quartile were associated with lung cancer in the NCI-MD study (IL-6, odds ratio [OR] = 3.29, 95% confidence interval [CI] = 1.88 to 5.77; IL-8, OR = 2.06, 95% CI = 1.19 to 3.57) and with lung cancer risk in the PLCO study (IL-6, OR = 1.48, 95% CI = 1.04 to 2.10; IL-8, OR = 1.57, 95% CI = 1.10 to 2.24), compared with the lowest quartile. In the PLCO study, increased IL-6 levels were only associated with lung cancer diagnosed within 2 years of blood collection, whereas increased IL-8 levels were associated with lung cancer diagnosed more than 2 years after blood collection (OR = 1.57, 95% CI = 1.15 to 2.13). The 10-year standardized absolute risks of lung cancer in the PLCO study were highest among current smokers with high IL-8 and CRP levels (absolute risk = 8.01%, 95% CI = 5.77% to 11.05%).

CONCLUSIONS

Although increased levels of both serum IL-6 and IL-8 are associated with lung cancer, only IL-8 levels are associated with lung cancer risk several years before diagnosis. Combination of IL-8 and CRP are more robust biomarkers than either marker alone in predicting subsequent lung cancer.

Lung cancer risk prediction: Prostate, Lung, Colorectal And Ovarian Cancer Screening Trial models and validation

INTRODUCTION

Identification of individuals at high risk for lung cancer should be of value to individuals, patients, clinicians, and researchers. Existing prediction models have only modest capabilities to classify persons at risk accurately.

METHODS

Prospective data from 70 962 control subjects in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO) were used in models for the general population (model 1) and for a subcohort of ever-smokers (N = 38 254) (model 2). Both models included age, socioeconomic status (education), body mass index, family history of lung cancer, chronic obstructive pulmonary disease, recent chest x-ray, smoking status (never, former, or current), pack-years smoked, and smoking duration. Model 2 also included smoking quit-time (time in years since ever-smokers permanently quit smoking). External validation was performed with 44 223 PLCO intervention arm participants who completed a supplemental questionnaire and were subsequently followed. Known available risk factors were included in logistic regression models. Bootstrap optimism-corrected estimates of predictive performance were calculated (internal validation). Nonlinear relationships for age, pack-years smoked, smoking duration, and quit-time were modeled using restricted cubic splines. All reported P values are two-sided.

RESULTS

During follow-up (median 9.2 years) of the control arm subjects, 1040 lung cancers occurred. During follow-up of the external validation sample (median 3.0 years), 213 lung cancers occurred. For models 1 and 2, bootstrap optimism-corrected receiver operator characteristic area under the curves were 0.857 and 0.805, and calibration slopes (model-predicted probabilities vs observed probabilities) were 0.987 and 0.979, respectively. In the external validation sample, models 1 and 2 had area under the curves of 0.841 and 0.784, respectively. These models had high discrimination in women, men, whites, and nonwhites.

CONCLUSION

The PLCO lung cancer risk models demonstrate high discrimination and calibration.

Screening and early detection of lung cancer

Lung cancer with an estimated 342,000 deaths in 2008 (20% of total) is the most common cause of death from cancer, followed by colorectal cancer (12%), breast cancer (8%), and stomach cancer (7%) in Europe. In former smokers, the absolute lung cancer risk remains higher than in never-smokers; these data therefore call for effective secondary preventive measures for lung cancer in addition to smoking cessation programs. This review presents and discusses the most recent advances in the early detection and screening of lung cancer.An overview of randomized controlled computerized tomography-screening trials is given, and the role of bronchoscopy and new techniques is discussed. Finally, the approach of (noninvasive) biomarker testing in the blood, exhaled breath, sputum, and bronchoscopic specimen is reviewed.

Scar carcinoma of the lung: a historical perspective

Lung scar carcinoma (SC) was first described by Friedrich in 1939 as a type of lung cancer that originates around peripheral scars in the lung. Scarring in the lung can result from a variety of infections, injuries, and lung diseases. Scars can also be due to repeated episodes of tumor necrosis and healing. SCs are typically found as subpleural adenocarcinomas with retraction or puckering of the overlying pleura. They were considered a histologic curiosity that was promoted for decades until doubts about their existence were raised in the 1980s. Finding type III collagen, type V collagen, and myofibroblasts characteristic of fibrosis in the scars, finally reversed the original SC concept. The presence of type III collagen and extracellular matrix suggested an ongoing fibrosing process secondary to host response to the neoplasm. The high concentration of type III collagen in SC indicates that the fibrous tissue is in an active immature state compared with noneuplastic fibrous tissue, which is mature and contains type I and type V collagen. A recent cohort analysis of data from the PLCO (Prostate, Lung, Colorectal and Ovarian) cancer screening trial demonstrated a correlation between the presence of scar and the development of carcinoma, but the causation of this association has to be determined by future studies. The role of inflammation, infections, and smoking in the development of cancer is discussed in this article. Additional research is necessary to determine if lung scarring detected by imaging requires clinical monitoring in the context of the development of lung cancer when a defined set of risk factors is identified.

Association between levels of C-reactive protein and leukocytes and cancer: three repeated measurements in the Swedish AMORIS study

OBJECTIVE

To study levels of C-reactive protein (CRP) and leukocytes, as inflammatory markers, in the context of cancer risk.

METHODS

From the Apolipoprotein MOrtality RISk (AMORIS) study, we selected 102,749 persons with one measurement and 9,273 persons with three repeated measurements of CRP and leukocytes. Multivariate Cox proportional hazards regression was applied to categories of CRP (<10, 10-15, 15-25, 25-50, >50 g/L) and quartiles of leukocytes. An inflammation-based predictive score (IPS) indicated whether someone had CRP levels of more than 10 mg/L combined with leukocytes of more than 10×10(9)/L. Reverse causality was assessed by excluding those with less than 3, 5, or 7 years of follow-up. To analyze repeated measurements of CRP and leukocytes, the repeated IPS (IPSr) was calculated by adding the IPS of each measurement.

RESULTS

In the cohort with one measurement, there was a positive trend between CRP and risk of developing cancer, with the lowest category being the 0.99 (0.92-1.06), 1.28 (1.11-1.47), 1.27 (1.09-1.49), and 1.22 (1.01-1.48) for the second to fifth categories, respectively. This association disappeared when excluding those with follow-up of less than 3, 5, or 7 years. The association between leukocytes and cancer was slightly stronger. In the cohort with repeated measurements, the IPSr was strongly associated with cancer risk: 1.87 (1.33-2.63), 1.51 (0.56-4.06), and 4.46 (1.43-13.87) for IPSr=1, 2, and 3 compared with IPSr=0. The association remained after excluding those with follow-up of less than 1 year.

CONCLUSIONS AND IMPACT

Our large, prospective cohort study adds evidence for a link between inflammatory markers and cancer risk by using repeated measurements and ascertaining reverse causality.

Endothelial cell-specific deletion of transcription factor FoxM1 increases urethane-induced lung carcinogenesis

Vascular endothelial cells provide essential support to the tumor microenvironment, but little is known about the transcriptional control of endothelial functions during tumorigenesis. Here we define a critical role for the Forkhead transcription factor FoxM1 in modulating the development of tumor-associated endothelial cells. Pulmonary tumorigenesis induced by urethane administration was compared in mice genetically deleted for FoxM1 in endothelial cells (enFoxm1(-/-) mice). Notably, lung tumor number and size were increased in enFoxm1(-/-) mice. Increased tumorigenesis was associated with increased proliferation of tumor cells and increased expression of c-Myc and cyclin D1. Furthermore, perivascular infiltration by inflammatory cells was elevated and inflammatory cells in BAL fluid were increased. Expression of Flk-1 (vascular endothelial growth factor receptor 2) and FoxF1, known regulators of pulmonary inflammation, was decreased in enFoxm1(-/-) mice. siRNA-mediated knockdown of FoxM1 in endothelial cells reduced Flk-1 and FoxF1 expression, which was driven by direct transcriptional induction by FoxM1 as target genes. Endothelial specific deletion of FoxM1 in vivo or in vitro also decreased expression of Sfrp1 (secreted frizzled-related protein 1), a known inhibitor of canonical Wnt signaling, in a manner that was associated with increased Wnt signaling. Taken together, our results suggest that endothelial-specific expression of FoxM1 limits lung inflammation and canonical Wnt signaling in lung epithelial cells, thereby restricting lung tumorigenesis.

Chronic immune stimulation as a contributing cause of chronic disease in opiate addiction including multi-system ageing

Evidence of immune stimulation has been noted in opiate dependent patients for many decades. Documented changes have included lymphadenopathy, round cell infiltration of the hepatic portal triads, diffuse peri-bronchitis, hyperglobulinaemia, lymphocytosis, monocytosis, systemic cytokine stimulation, and cytokine and chemokine activation within the neuraxis. A parallel literature describes an elevated list of chronic degenerative disease as common in such patients including neurodegenerative conditions, atherosclerosis, nephrosclerosis, hepatic fibrosis and cirrhosis, chronic obstructive and fibrotic lung disease, osteoporosis, chronic periodontitis, various cancers, hair greying, and stem cell suppression. All of these disorders are now known to have an important immunological role in their pathogenic pathways. The multisystem nature of these myriad changes strongly suggest that the ageing process itself is stimulated in these patients. The link between the immunostimulation on the one hand and the elevated and temporally advanced nature of the chronic degenerative diseases on the other appears not to have been made in the literature. Moreover as immunostimulation is also believed to be an important, potent and principal contributor to the ageing process it appears that experimental and studies of this putative link are warranted. Verification of such an hypothesis would also carry management implications for dose and duration of chronic pain and addiction treatment, pharmacotherapeutic selection, and novel treatments such as long term naltrexone implant therapy and heroin trials.