Influence of ABO blood group on susceptibility to different pathological types of lung cancer: a retrospective study.

PURPOSE: Current research has shown a link between ABO blood group and many diseases. The purpose of this study aimed to investigate the influence of the ABO blood group on the risk of developing different pathological types of lung cancer. MATERIALS AND METHODS: This retrospective study was composed of 7681 patients with lung cancer and 12, 671 non-lung cancer patients who were admitted to the First Affiliated Hospital of Nanchang University from January 2016 to January 2021. The subjects with lung cancer were grouped into small cell lung cancer group (n = 725), lung adenocarcinoma group (n = 4520), and lung squamous cell carcinoma group (n = 2286) according to pathological types. The ABO blood group distribution of each lung cancer type group was compared with that of the control group. Statistical analysis was determined with chi-square and logistic regression. RESULTS: Univariate analysis showed that the ABO blood group distribution of lung adenocarcinoma, lung squamous cell carcinoma, and small cell lung cancer was different from that of the control group (P < 0.01). After adjusting for age, sex, smoking history, and drinking history, logistic regression analysis showed that the risk of lung adenocarcinoma in blood type O was higher than that in blood type A (P < 0.01). There was no significant difference in ABO blood group composition between small cell lung cancer group, lung squamous cell carcinoma group, and control group (P > 0.05). In addition, gender and age have an influence on all three types of lung cancer (P < 0.01). Smoking was a risk factor in lung squamous cell carcinoma and small cell carcinoma (P < 0.01). Alcohol consumption was a risk factor in lung adenocarcinoma (P < 0.01). CONCLUSION: ABO blood group may be correlated with the occurrence of lung adenocarcinoma in Jiangxi province, but not with lung squamous cell carcinoma and small cell carcinoma.

[Disseminated combined small cell carcinoma with graft involvement after kidney transplantation from a deceased donor to two patients]. / Disseminirovannyi kombinirovannyi melkokletochnyi rak s porazheniem transplantatov posle peresadki pochek ot umershego donora dvum bol'nym.

The paper describes cases of disseminated small-cell carcinoma after kidney transplantation from a deceased donor to two patients. Microscopic examination showed that the kidney graft tumor consisted of tightly packed small rounded cells with hyperchromatic nuclei and a narrow cytoplasmic rim with invisible nucleoli. The mitotic index was 25-40/2 mm2. Azzopardi's phenomenon and crush artifact were detected in the tumor. Giant cell and large cell components were 30-40% of the area of sections. Immunohistochemical examination revealed the expression of synaptophysin, chromogranin A, CD56, TTF-1, HMWK, СК7, СК18, and Ki-67 (80% of tumor cells). Histological findings and immunophenotype in both cases led to the conclusion about combined small cell carcinoma with renal graft involvement. Both patients died from tumor dissemination 9 and 11 months after transplantations. In reviewing the literature, the authors found only one such observation.

Lung cancer risk among bricklayers in a pooled analysis of case-control studies.

Bricklayers may be exposed to several lung carcinogens, including crystalline silica and asbestos. Previous studies that analyzed lung cancer risk among these workers had several study design limitations. We examined lung cancer risk among bricklayers within SYNERGY, a large international pooled analysis of case-control studies on lung cancer and the joint effects of occupational carcinogens. For men ever employed as bricklayers we estimated odds ratios (OR) and 95% confidence intervals (CI) adjusted for study center, age, lifetime smoking history and employment in occupations with exposures to known or suspected lung carcinogens. Among 15,608 cases and 18,531 controls, there were 695 cases and 469 controls who had ever worked as bricklayers (OR: 1.47; 95% CI: 1.28-1.68). In studies using population controls the OR was 1.55 (95% CI: 1.32-1.81, 540/349 cases/controls), while it was 1.24 (95% CI: 0.93-1.64, 155/120 cases/controls) in hospital-based studies. There was a clear positive trend with length of employment (p < 0.001). The relative risk was higher for squamous (OR: 1.68, 95% CI: 1.42-1.98, 309 cases) and small cell carcinomas (OR: 1.78, 95% CI: 1.44-2.20, 140 cases), than for adenocarcinoma (OR: 1.17, 95% CI: 0.95-1.43, 150 cases) (p-homogeneity: 0.0007). ORs were still elevated after additional adjustment for education and in analyses using blue collar workers as referents. This study provided robust evidence of increased lung cancer risk in bricklayers. Although non-causal explanations cannot be completely ruled out, the association is plausible in view of the potential for exposure to several carcinogens, notably crystalline silica and to a lesser extent asbestos.

Genitourinary small cell malignancies: prostate and bladder.

Small cell carcinoma is an aggressive malignancy often associated with dismal prognosis due to the presence of advanced disease. Small cell malignancies, initially described in the lung (small cell carcinoma of the lung), can occur in extrapulmonary sites, such as prostate (small cell carcinoma of the prostate) and bladder (small cell carcinoma of the bladder), with similar clinicopathologic outcomes. There has been a paradigm shift in the management of small cell carcinoma of the lung from initial surgical treatment to use of chemotherapy followed by local therapies. Such treatment modalities have been applied to small cell carcinoma of the prostate and the bladder, with promise in improving patient survival. Use of platinum-based combination chemotherapy followed by surgical resection and/or radiation offers the most benefit. Further investigation at the molecular level may offer targeted therapies earlier in the course of the disease.

Smoking, inflammation and small cell lung cancer: recent developments.

Small cell lung cancer (SCLC) accounts for 15 % of all lung tumors and represents an invasive neuroendocrine malignancy with poor survival rates. This cancer is highly prevalent in smokers and characterized by inactivation of p53 and retinoblastoma. First in vitro expansion of circulating tumor cells (CTCs) of SCLC patients allowed for investigation of the cell biology of tumor dissemination. In the suggested CTC SCLC model, the primary tumor attracts and educates tumor-promoting and immunosuppressive macrophages which in turn arm CTCs to spread and generate distal lesions. Preexisting inflammatory processes associated with chronic obstructive pulmonary disease (COPD) seem to potentiate the subsequent activity of tumor-associated macrophages (TAM). Activation of signal transducer and activator of transcription 3 (STAT3) and expression of chitinase-3-like 1/YKL-40 in SCLC CTCs seems to be associated with drug resistance. In conclusion, inflammation-associated generation of invasive and chemoresistant CTCs most likely explains the characteristic features of SCLC, namely early dissemination and rapid failure of chemotherapy.

Heavy smoking and lung cancer: are women at higher risk? Result of the ICARE study.

BACKGROUND: Whether women are more or equally susceptible to the carcinogenic effects of cigarette smoke on the lungs compared with men is a matter of controversy. Using a large French population-based case-control study, we compared the lung cancer risk associated with cigarette smoking by gender. METHODS: The study included 2276 male and 650 female cases and 2780 male and 775 female controls. Lifetime smoking exposure was represented by the comprehensive smoking index (CSI), which combines the duration, intensity and time since cessation of smoking habits. The analysis was conducted among the ever smokers. All of the models were adjusted for age, department (a regional administrative unit), education and occupational exposures. RESULTS: Overall, we found that the lung cancer risk was similar among men and women. However, we found that women had a two-fold greater risk associated with a one-unit increase in CSI than men of developing either small cell carcinoma (OR=15.9, 95% confidence interval (95% CI) 7.6, 33.3 and 6.6, 95% CI 5.1, 8.5, respectively; P<0.05) or squamous cell carcinoma (OR=13.1, 95% CI 6.3, 27.3 and 6.1, 95% CI 5.0, 7.3, respectively; P<0.05). The association was similar between men and women for adenocarcinoma. CONCLUSION: Our findings suggest that heavy smoking might confer to women a higher risk of lung cancer as compared with men.

Molecular and cellular biology of neuroendocrine lung tumors: evidence for separate biological entities.

Pulmonary neuroendocrine tumors (NETs) are traditionally described as comprising a spectrum of neoplasms, ranging from low grade typical carcinoids (TCs) via the intermediate grade atypical carcinoids (ACs) to the highly malignant small cell lung cancers (SCLCs) and large cell neuroendocrine carcinomas (LCNECs). Recent data, however, suggests that two categories can be distinguished on basis of molecular and clinical data, i.e. the high grade neuroendocrine (NE) carcinomas and the carcinoid tumors. Bronchial carcinoids and SCLCs may originate from the same pulmonary NE precursor cells, but a precursor lesion has only been observed in association with carcinoids, termed diffuse idiopathic pulmonary neuroendocrine cell hyperplasia. The occurrence of mixed tumors exclusively comprising high grade NE carcinomas also supports a different carcinogenesis for these two groups. Histopathologically, high grade NE lung tumors are characterized by high mitotic and proliferative indices, while carcinoids are defined by maximally 10 mitoses per 2mm(2) (10 high-power fields) and rarely have Ki67-proliferative indices over 10%. High grade NE carcinomas are chemosensitive tumors, although they usually relapse. Surgery is often not an option due to extensive disease at presentation and early metastasis, especially in SCLC. Conversely, carcinoids are often insensitive to chemo- and radiation therapy, but cure can usually be achieved by surgery. A meta-analysis of comparative genomic hybridization studies performed for this review, as well as gene expression profiling data indicates separate clustering of carcinoids and carcinomas. Chromosomal aberrations are much more frequent in carcinomas, except for deletion of 11q, which is involved in the whole spectrum of NE lung tumors. Deletions of chromosome 3p are rare in carcinoids but are a hallmark of the high grade pulmonary NE carcinomas. On the contrary, mutations of the multiple endocrine neoplasia type 1 (MEN1) gene are restricted to carcinoid tumors. Many of the differences between carcinoids and high grade lung NETs can be ascribed to tobacco consumption, which is strongly linked to the occurrence of high grade NE carcinomas. Smoking causes p53 mutations, very frequently present in SCLCs and LCNECs, but rarely in carcinoids. It further results in other early genetic events in SCLCs and LCNECs, such as 3p and 17p deletions. Smoking induces downregulation of E-cadherin and associated epithelial to mesenchymal transition. Also, high grade lung NETs display higher frequencies of aberrations of the Rb pathway, and of the intrinsic and extrinsic apoptotic routes. Carcinoid biology on the other hand is not depending on cigarette smoke intake but rather characterized by aberrations of other specific genetic events, probably including Menin or its targets and interaction partners. This results in a gradual evolution, most likely from proliferating pulmonary NE cells via hyperplasia and tumorlets towards classical carcinoid tumors. We conclude that carcinoids and high grade NE lung carcinomas are separate biological entities and do not comprise one spectrum of pulmonary NETs. This implies the need to reconsider both diagnostic as well as therapeutic approaches for these different groups of malignancies.

Induction of small cell lung cancer by somatic inactivation of both Trp53 and Rb1 in a conditional mouse model.

Small cell lung cancer (SCLC) is a highly aggressive human tumor with a more than 95% mortality rate. Its ontogeny and molecular pathogenesis remains poorly understood. We established a mouse model for neuroendocrine (NE) lung tumors by conditional inactivation of Rb1 and Trp53 in mouse lung epithelial cells. Mice carrying conditional alleles for both Rb1 and Trp53 developed with high incidence aggressive lung tumors with striking morphologic and immunophenotypic similarities to SCLC. Most of these tumors, which we designate MSCLC (murine small cell lung carcinoma), diffusely spread through the lung and gave rise to extrapulmonary metastases. In our model, inactivation of both Rb1 and p53 was a prerequisite for the pathogenesis of SCLC.

Retransplantation for donor-derived neuroendocrine tumor.

Although tumor transmission through liver transplantation (LT) is a rare occurrence, the consequences can be devastating, even when a very aggressive management approach is adopted. We report the case of a donor-derived small cell neuroendocrine tumor (NET) in a patient who underwent LT for cholangiocarcinoma. Despite locoregional therapy, chemotherapy and ultimately retransplantation, the patient died from metastases. The high grade nature of the NET was the most important determinant of prognosis in this case. Our experience suggests that retransplantation for donor-derived NET should only be considered when tumor biology is favorable.

High prevalence of multiple human papillomavirus infection in Japanese patients with invasive uterine cervical cancer.

OBJECTIVE: Multiple human papillomavirus (HPV) infection of the uterine cervix has been suggested as a risk factor for persistent HPV infection, resulting in the development of invasive cervical cancer. The aim of this study was to reveal the actual state of multiple HPV infection in Japanese patients with invasive cervical cancer. METHODS: Sixty fresh-frozen invasive cervical cancer tissues were examined for genotyping of HPV. The presence of HPV genotypes was determined with an HPV-DNA array, which can discriminate 25 different HPV genotypes with high sensitivity and specificity. RESULTS: Among 60 samples, 59 (96.7%) were positive for HPV. The three common genotypes were HPV-16 (83.3%), HPV-18 (45.0%) and HPV-52 (28.3%). Multiple HPV infection was observed in 47 of 60 samples (78.3%), among which 42 were infected with more than one high-risk genotype (70.0%). Multiple high-risk HPV infection was significantly more prevalent in patients below 40 years old (14/15, 93.3%) than in patients 40 years of age and over (28/45, 62.2%). CONCLUSION: The HPV-DNA array is the preferred method to detect HPV genotypes. Multiple HPV infection in Japanese patients with invasive cervical cancer seemed to be more frequent than reported in the literature.

Cigarette smoking and trends in lung cancer incidence in Lithuania: an analysis by histological type.

OBJECTIVE: The aim of this study was to investigate time trends of lung cancer incidence by histological type in Lithuania during the period from 1996 to 2005. The results were evaluated in relation to tobacco smoking trends. MATERIAL AND METHODS: The incidence rates of the most common lung cancer cell types (squamous cell carcinoma, adenocarcinoma, small cell carcinoma, other types, and morphologically not specified cases) were studied using data from the Lithuanian Cancer Registry. The world standard population was used for age adjustment. Data on tobacco smoking in Lithuania were obtained from various published sources. RESULTS: Among men, squamous cell carcinoma was the most common type of lung cancer. The age-adjusted rates of squamous cell carcinoma decreased from 25 per 100,000 in 1998-1999 to 19.1 per 100,000 in 2004-2005; the incidence rates for adenocarcinoma and small cell carcinoma rose to around 7 per 100,000 in 2002-2003. Among women, adenocarcinoma was the most common histological type. The incidence rates for adenocarcinoma increased to 1.9 per 100,000 until 2002-2003 and thereafter did not change. The rates of squamous cell carcinoma in women were relatively stable at around 1.1 per 100,000. In 2000, the prevalence of regular smoking among men and women peaked at 51.5% and 15.8%, respectively; there was a significant change from smoking nonfilter cigarettes to filter cigarettes. CONCLUSIONS: The decreasing squamous cell carcinoma rates among men and increasing adenocarcinoma rates among men and women are similar to those reported in other European countries and may be due to a shift from nonfilter type cigarettes to filter type.

Increased activity of procoagulant factors in patients with small cell lung cancer.

Small cell lung cancer (SCLC) patients have augmented risk of developing venous thromboembolism, but the mechanisms triggering this burden on the coagulation system remain to be understood. Recently, cell-derived microparticles carrying procoagulant phospholipids (PPL) and tissue factor (TF) in their membrane have attracted attention as possible contributors to the thrombogenic processes in cancers. The aims of this study were to assess the coagulation activity of platelet-poor plasma from 38 SCLC patients and to provide a detailed procoagulant profiling of small and large extracellular vesicles (EVs) isolated from these patients at the time of diagnosis, during and after treatment compared to 20 healthy controls. Hypercoagulability testing was performed by thrombin generation (TG), procoagulant phospholipid (PPL), TF activity, Protein C, FVIII activity and cell-free deoxyribonucleic acid (cfDNA), a surrogate measure for neutrophil extracellular traps (NETs). Our results revealed a coagulation activity that is significantly increased in the plasma of SCLC patients when compared to age-related healthy controls, but no substantial changes in coagulation activity during treatment and at follow-up. Although EVs in the patients revealed an increased PPL and TF activity compared with the controls, the TG profiles of EVs added to a standard plasma were similar for patients and controls. Finally, we found no differences in the coagulation profile of patients who developed VTE to those who did not, i.e. the tests could not predict VTE. In conclusion, we found that SCLC patients display an overall increased coagulation activity at time of diagnosis and during the disease, which may contribute to their higher risk of VTE.

MET as a target for treatment of chest tumors.

The receptor tyrosine kinase MET has been studied of a large variety of human cancers, including lung and mesothelioma. The MET receptor and its ligand HGF (hepatocyte growth factor) play important roles in cell growth, survival and migration, and dysregulation of the HGF-MET pathway leads to oncogenic changes including tumor proliferation, angiogenesis and metastasis. In small cell lung cancer (SCLC), non-small cell lung cancer (NSCLC), and malignant pleural mesothelioma (MPM), MET is dysregulated via overexpression, constitutive activation, gene amplification, ligand-dependent activation, mutation or epigenetic mechanisms. New drugs targeted against MET and HGF are currently being investigated in vitro and in vivo, with promising results. These drugs function at a variety of steps within the HGF-MET pathway, including MET expression at the RNA or protein level, the ligand-receptor interaction, and tyrosine kinase function. This paper will review the structure, function, mechanisms of tumorigenesis, and potential for therapeutic inhibition of the MET receptor in lung cancer and mesothelioma.

Small cell carcinoma of the lung: macrophage-specific antigens suggest hemopoietic stem cell origin.

Four surface antigens previously recognized only in macrophages are present on human small cell lung carcinoma cells and tumors. Cancerous cells may arise from macrophage precursors in bone marrow, and these precursors migrate to lung to participate in the repair of damaged tissue produced by continuous heavy smoking. The characteristic presence of neuropeptides such as bombesin in small cell carcinoma, when considered along with these findings, presents new possibilities for the role of such peptides in nervous, endocrine, and immune system function.

Spread Through Air Spaces (STAS) Is Prognostic in Atypical Carcinoid, Large Cell Neuroendocrine Carcinoma, and Small Cell Carcinoma of the Lung.

INTRODUCTION: Tumor spread through air spaces (STAS) has prognostic significance in lung adenocarcinoma and squamous cell carcinoma. We sought to investigate the prognostic importance of STAS in lung neuroendocrine tumors (NETs). METHODS: All tumor slides from patients with resected pathologic stage I to III lung NETs (N = 487) (299 with typical carcinoid [TC], 38 with atypical carcinoid [AC], 93 with large cell neuroendocrine carcinoma [LCNEC], and 57 with SCLC) treated between 1992 and 2012 were evaluated for presence of STAS. Cumulative incidence of recurrence (CIR) and lung cancer-specific cumulative incidence of death (LC-CID) were analyzed by using a competing-risks approach. RESULTS: STAS was identified in 26% of NETs (16% of TCs, 37% of ACs, 43% of LCNECs, and 46% of SCLCs). STAS was associated with distant metastasis, as well as with higher CIR and LC-CID in the overall cohort and in the AC, LCNEC, and SCLC cohorts (owing to a small number of recurrences and deaths [<5], prognostic analysis was not performed in the TC cohort). In multivariable analysis stratified by stage, STAS was significantly associated with higher CIR (subhazard ratio = 2.85, 95% confidence interval: 1.73-4.68, p < 0.001) and LC-CID (subhazard ratio = 2.72, 95% confidence interval: 1.57-4.70, p < 0.001), independent of histologic subtype. STAS was independently associated with CIR and LC-CID in the LCNEC cohort and LC-CID in the SCLC cohort. CONCLUSIONS: In patients with lung NETs, STAS is associated with early distant metastasis and worse LC-CID. In patients with LCNEC or SCLC, STAS is an independent poor prognostic factor.

Small cell carcinoma of the kidney: a case report and analysis of data from the Surveillance, Epidemiology, and End Results registry.

BACKGROUND: Primary small cell carcinoma of the kidney is an extremely rare neoplasm. The clinical features of small cell carcinoma of the kidney are not well established due to its rarity and scarcity of case reports. We present an unusual case of small cell carcinoma of the kidney complicated by syndrome of inappropriate antidiuretic hormone secretion. We identify cases using a population-based dataset from the Surveillance, Epidemiology, and End Results registry and compare small cell carcinoma of the kidney with small cell carcinoma of the lung. CASE PRESENTATION: A 69-year-old Filipino man presented with hematuria for 1 month. A computed tomography scan demonstrated a large left kidney mass with biopsy demonstrating small cell carcinoma. Within 2 months he developed dizziness and was found to have a metastatic lesion to his brain. He was hyponatremic due to syndrome of inappropriate antidiuretic hormone secretion. He did not receive chemotherapy due to his poor functional status. He died within 8 months of presentation. RESULTS: From 1973 to 2013, 60 cases with small cell carcinoma of the kidney were identified in the Surveillance, Epidemiology, and End Results registry. Most (62%) presented with extensive stage, which occurred predominantly in white men in their seventh decade. The median overall survival with extensive stage small cell carcinoma of the kidney was 3 months versus 11 months with limited stage of small cell carcinoma of the kidney; this was worse than small cell carcinoma of the lung with a median survival of 5 and 13 months, respectively. CONCLUSION: We present a rare case of small cell carcinoma of the kidney complicated by syndrome of inappropriate antidiuretic hormone secretion. This adds to our understanding of the clinical features of small cell carcinoma of the kidney. Furthermore, this is the first population-based study of small cell carcinoma of the kidney using the Surveillance, Epidemiology, and End Results database. Analysis shows that overall survival is worse in small cell carcinoma of the kidney relative to that of small cell carcinoma of the lung. Small cell carcinoma of the kidney presents very aggressively, and further studies are needed to develop a standard of care.

Pan-cancer Convergence to a Small-Cell Neuroendocrine Phenotype that Shares Susceptibilities with Hematological Malignancies.

Small-cell neuroendocrine cancers (SCNCs) are an aggressive cancer subtype. Transdifferentiation toward an SCN phenotype has been reported as a resistance route in response to targeted therapies. Here, we identified a convergence to an SCN state that is widespread across epithelial cancers and is associated with poor prognosis. More broadly, non-SCN metastases have higher expression of SCN-associated transcription factors than non-SCN primary tumors. Drug sensitivity and gene dependency screens demonstrate that these convergent SCNCs have shared vulnerabilities. These common vulnerabilities are found across unannotated SCN-like epithelial cases, small-round-blue cell tumors, and unexpectedly in hematological malignancies. The SCN convergent phenotype and common sensitivity profiles with hematological cancers can guide treatment options beyond tissue-specific targeted therapies.

Aberrant promoter hypermethylation in serum DNA from patients with silicosis.

It is well established that patients with silicosis are at high risk for lung cancer; however, it is difficult to detect lung cancer by chest radiography during follow-up treatment of patients with silicosis because of preexisting diffuse pulmonary shadows. The purpose of this study is to evaluate the usefulness of detection of serum DNA methylation for early detection of lung cancer in silicosis. Serum samples from healthy controls (n = 20) and silicosis patients with (n = 11) and without (n = 67) lung cancer were tested for aberrant hypermethylation at the promoters of the DNA repair gene O(6)-methylguanine-DNA methyltransferase (MGMT), p16(INK4a), ras association domain family 1A (RASSF1A), the apoptosis-related gene death-associated protein kinase (DAPK) and retinoic acid receptor beta (RARbeta) by methylation-specific polymerase chain reaction. Aberrant promoter methylation in at least one of five tumor suppressor genes was detected more frequently in the serum DNA of silicosis patients with lung cancer than in that of patients without it (P = 0.006). Furthermore, the odds ratio of having lung cancer was 9.77 (P = 0.009) for those silicosis patients with methylation of at least one gene. Extended exposure to silica (>30 years) was correlated with an increased methylation frequency (P = 0.017); however, methylation status did not correlate with age, smoking history or radiographic findings of silicosis. These results suggest that testing for aberrant promoter methylation of tumor suppressor genes using serum DNA may facilitate early detection of lung cancer in patients with silicosis.

Association between lung cancer risk and single nucleotide polymorphisms in the first intron and codon 178 of the DNA repair gene, O6-alkylguanine-DNA alkyltransferase.

The association between lung cancer risk and 2 polymorphisms, rs12268840 and rs2308327 (codon K178R), in the DNA repair protein, O(6)-alkylguanine-DNA alkyltransferase, which are associated with interindividual differences in activity, have been investigated in 3 hospital-based case-control studies. Genotyping was carried out on 617 subjects of whom 255 had lung cancer. In 2 of the 3 series, there was a significant inverse association between the 178R allele and case status (p < 0.05). In a meta-analysis, the odds ratio (95% CI) associated with the 178R allele relative to the 178K allele was 0.64 (0.45-0.92, p = 0.01) and 0.51 (0.24-1.11, p = 0.09) in fixed effects and random effects models, respectively. In a pooled analysis, after adjustment for sex, age, pack years and series, the OR (95% CI) for a heterozygote was 0.67 (0.45-1.01) and for a 178R homozygote was 0.10 (0.01-0.94); the trend for a decreased risk with the number of R alleles was significant (p = 0.008). This trend was particularly pronounced in heavy smokers (trend test p = 0.003), but not significant in light smokers (p = 0.73). There was no evidence of an association between rs12268840 and lung cancer risk. These results suggest that the R allele may protect against lung cancer, specifically in heavy smokers, an effect that may result from this polymorphism affecting the function of the MGMT protein and/or levels in MGMT activity.