Analysis of the relationship between p53 immunohistochemical expression and risk factors for lung cancer, with special emphasis on residential radon exposure

An overview on the relationship between residential radon and lung cancer: what we know and future research

We aim to provide an overview of the research available on indoor radon and lung cancer, with a special focus on Spanish investigations. Early studies on underground miners established the link between radon and lung cancer, which was later confirmed for the general population by residential case-control studies. Spain contributed with extensive evidence, including 5 multicentric, hospital-based, case-control studies in the last 30 years, exploring diverse aspects, such as radon's effect on never-smokers, molecular pathways linking radon exposure to lung cancer risk, survival rates, mortality burden, and occupational exposure. There is a well-established causal association between radon with lung cancer. Despite pioneering research performed in our country by the Galician Radon Laboratory, particularly on driver genes, the evidence on the potential molecular pathways which makes radon a carcinogen is sparse. Also, relevant questions on the potential association of radon exposure with the induction of other diseases are still pending.

Pathways Related to the Anti-Cancer Effects of Metabolites Derived from Cerrado Biome Native Plants: An Update and Bioinformatics Analysis on Oral Squamous Cell Carcinoma

BACKGROUND

Oral cancer is a significant health problem worldwide. Oral squamous cell carcinoma (OSCC) is a malignant neoplasm of epithelial cells that mostly affects different anatomical sites in the head and neck and derives from the squamous epithelium or displays similar morphological characteristics. Generally, OSCC is often the end stage of several changes in the stratified squamous epithelium, which begin as epithelial dysplasia and progress by breaking the basement membrane and invading adjacent tissues. Several plant-based drugs with potent anti-cancer effects are considered inexpensive treatments with limited side effects for cancer and other diseases.

OBJECTIVE

The aim of this review is to explore whether some Brazilian plant extracts or constituents exhibit anti-tumorigenic activity or have a cytotoxic effect on human oral carcinoma cells.

METHODS

Briefly, OSCC and several metabolites derived from Brazilian plants (i.e., flavonoids, vinblastine, irinotecan, etoposide and paclitaxel) were used as keywords to search the literature on PubMed, GenBank and GeneCards.

RESULTS

The results showed that these five chemical compounds found in Cerrado Biome plants exhibit anti-neoplastic effects. Evaluating the compounds revealed that they play a main role in the regulation of cell proliferation.

CONCLUSION

Preserving and utilising the biodiversity of our planet, especially in unique ecosystems, such as the Cerrado Biome, may prove essential to preserving and promoting human health in modern contexts.

miR-19 in blood plasma reflects lung cancer occurrence but is not specifically associated with radon exposure

Radon is one of the most powerful carcinogens, particularly in terms of lung cancer onset and development. miRNAs may be considered not only as markers of the ongoing tumorigenesis but also as a hallmark of exposure to radiation, including radon and its progeny. Therefore, the purpose of the present study was to estimate the value of plasma miR-19b-3p level as the prospective marker of the response to radon exposure in lung cancer pathogenesis. A total of 136 subjects were examined, including 49 radon-exposed patients with lung cancer, 37 patients with lung cancer without radon exposure and 50 age/sex matched healthy controls. Total RNA from blood samples was extracted and used to detect miR-19b-3p expression via reverse transcription quantitative-polymerase chain reaction. The 2-ΔΔCq method was used to quantify the amount of relative miRNA. The plasma level of p53 protein was determined using a Human p53 ELISA kit. Plasma miR-19b-3p level was significantly higher in the patients with lung cancer groups, compared with the healthy control group (P<0.0001). No other statistically significant differences were determined in the expression level of plasma miR-19b-3p between patients diagnosed with lung cancer exposed to radon and not exposed to radon. The expression level of free circulating miR-19b-3p was higher in the group of non-smoking patients with lung cancer, compared with smokers with lung cancer. The miR-19b-3p was 1.4-fold higher in non-smokers than in smokers (P<0.05). No association between plasma levels of p53 protein and miR-19b-3p freely circulating in patients with lung cancer was observed. No other statistically significant differences were determined in the plasma p53 protein level between patients diagnosed with lung cancer exposed and not exposed to radon. These results indicated that detection of miR-19b-3p levels in plasma potentially could be exploited as a noninvasive method for the lung cancer diagnostics. However, this miRNA is not suitable as the precise marker for radon impact.

Residential radon and lung cancer: a cohort study in Galicia, Spain

Case-control studies show an association between residential radon and lung cancer. The aim of this paper is to investigate this association through a cohort study. We designed an ambispective cohort study using the Galician radon map, Spain, with controls drawn from a previous case-control study. Subjects were recruited between 2002 and 2009. The data were cross-checked to ascertain lung cancer incidence and then analysed using a Cox regression model. A total of 2,127 subjects participated; 24 lung cancer cases were identified; 76.6% of subjects were drawn from the radon map. The adjusted hazard ratio was 1.2 (95%CI: 0.5-2.8) for the category of subjects exposed to 50Bq/m3 or more. This risk rose when subjects from the case-control study were analyzed separately. In conclusion, we did not observe any statistically significant association between residential radon exposure and lung cancer; however, it appears that with a sample of greater median age (such as participants from the case-control study), the risk of lung cancer would have been higher.

Chemotherapy in conjunction with traditional Chinese medicine for survival of elderly patients with advanced non-small-cell lung cancer: protocol for a randomized double-blind controlled trial

BACKGROUND

Traditional Chinese medicine (TCM) is considered an important complementary therapy with beneficial effects for cancer patients. Elderly patients with non-small-cell lung cancer (NSCLC) are a complex patient group with increasing co-morbidity and shrinking physiological reserve, and may derive substantial benefit from the supportive aspects of TCM. Researchers from Shanghai Longhua Hospital found that qi and yin deficiency is a common syndrome in patients with stage III or IV lung cancer. This project was designed to study the combination of single-agent chemotherapy with TCM methods of benefiting qi and yin in elderly patients with advanced NSCLC.

METHODS AND DESIGN

This is a double-blind controlled, multi-center, and prospective study with randomly selected participants from elderly NSCLC patients in China. Seventy-six patients who meet the inclusion criteria will be allocated into two groups, which will receive treatments of 3-week single-agent chemotherapy with TCM or placebo for four cycles. Progression-free survival (PFS) is the primary end point, and the secondary end points are overall survival, objective response rate, time-to-progression, and quality of life (EORTC QLQ-LC43, and TCM syndrome score). Meanwhile, other end points such as toxicity, side effects and safety of the treatments will be assessed.

DISCUSSION

Results from this study may provide evidence on the effectiveness, and parameters for the usage of single-agent chemotherapy combined with or without TCM on PFS of elderly patients with NSCLC.

TRIAL REGISTRATION

ClinicalTrials.gov. (Identifier: NCT01780181).

The cellular and molecular carcinogenic effects of radon exposure: a review

Radon-222 is a naturally occurring radioactive gas that is responsible for approximately half of the human annual background radiation exposure globally. Chronic exposure to radon and its decay products is estimated to be the second leading cause of lung cancer behind smoking, and links to other forms of neoplasms have been postulated. Ionizing radiation emitted during the radioactive decay of radon and its progeny can induce a variety of cytogenetic effects that can be biologically damaging and result in an increased risk of carcinogenesis. Suggested effects produced as a result of alpha particle exposure from radon include mutations, chromosome aberrations, generation of reactive oxygen species, modification of the cell cycle, up or down regulation of cytokines and the increased production of proteins associated with cell-cycle regulation and carcinogenesis. A number of potential biomarkers of exposure, including translocations at codon 249 of TP53 in addition to HPRT mutations, have been suggested although, in conclusion, the evidence for such hotspots is insufficient. There is also substantial evidence of bystander effects, which may provide complications when calculating risk estimates as a result of exposure, particularly at low doses where cellular responses often appear to deviate from the linear, no-threshold hypothesis. At low doses, effects may also be dependent on cellular conditions as opposed to dose. The cellular and molecular carcinogenic effects of radon exposure have been observed to be both numerous and complex and the elevated chronic exposure of man may therefore pose a significant public health risk that may extend beyond the association with lung carcinogenesis.

Residential radon exposure, histologic types, and lung cancer risk. A case-control study in Galicia, Spain

BACKGROUND

Lung cancer is an important public health problem, and tobacco is the main risk factor followed by residential radon exposure. Recommended exposure levels have been progressively lowered. Galicia, the study area, has high residential radon concentrations. We aim (i) to assess the risk of lung cancer linked to airborne residential radon exposure, (ii) to ascertain whether tobacco modifies radon risk, and (iii) to know whether there is a lung cancer histologic type more susceptible to radon.

METHODS

A hospital-based case-control design was conducted in two Spanish hospitals. Consecutive cases with histologic diagnosis of lung cancer and controls undergoing trivial surgery not tobacco-related were included. Residential radon was measured using standard procedures. Results were obtained using logistic regression.

RESULTS

Three hundred and forty-nine cases and 513 controls were included. Radon exposure posed a risk even with a low exposure, with those exposed to 50 to 100 Bq/m(3) having an OR of 1.87 [95% confidence interval (CI), 1.21-2.88] and of 2.21 (95% CI, 1.33-3.69) for those exposed to 148 Bq/m(3) or more. Tobacco increased appreciably the risk posed by radon, with an OR of 73 (95% CI, 19.88-268.14) for heavy smokers exposed to more than 147 Bq/m(3). Less frequent histologic types (including large cell carcinomas), followed by small cell lung cancer, had the highest risk associated with radon exposure.

CONCLUSIONS

The presence of airborne radon even at low concentrations poses a risk of developing lung cancer, with tobacco habit increasing considerably this risk.

IMPACT

Public health initiatives should address the higher risk of lung cancer for smokers exposed to radon.

Chemotherapy in Patients Older than or Equal to 75 Years with Advanced Non-small Cell Lung Cancer

Purpose

As the number of elderly patients diagnosed with non-small cell lung carcinoma (NSCLC) increases, the number of these patients receiving chemotherapy also increases. However, limited data exists regarding the use of chemotherapy in advanced NSCLC patients who are 75 years of age or older.

Materials and Methods

Between May 2002 and October 2008, data for 48 advanced NSCLC patients who were 75 years of age or older who had been treated with chemotherapy were retrospectively analyzed.

Results

The median age of study participants at the time of first line chemotherapy was 76 years (range, 75 to 87 years) and their median Charlson comorbidity index was 2 (range, 1 to 4). Of the total 48 patients, 43 patients (90%) were treated by platinum-based doublet as a first line chemotherapy regimen. Median progression free survival for first line chemotherapy was 5.7 months (95% confidence interval [CI], 4.93 to 6.47 months) with an overall response rate of 33.3%. After first line chemotherapy, only 14 of the 48 patients (29.2%) received second line chemotherapy. The median overall survival (OS) for these patients was 8.2 months (95% CI, 4.44 to 11.96 months). Multivariate analysis results indicated that female gender and having received second-line or more chemotherapy were independent prognostic factors for increased OS for all 48 patients. Charlson Index was not a significant independent prognostic factor for survival. There were 9 treatment related deaths due to infectious causes (18.8%).

Conclusion

Patients 75 years of age or older with advanced NSCLC may obtain clinical benefit from the administration of platinum-based doublet or single agent chemotherapy. However, oncologists must consider the aspect of safety in relation to the clinical benefits when managing this patient group.

Bibliography. Current world literature

This bibliography is compiled by clinicians from the journals listed at the end of this publication. It is based on literature entered into our database between 1 November 2007 and 31 October 2008 (articles are generally added to the database about two and a half months after publication). In addition, the bibliography contains every paper annotated by reviewers; these references were obtained from a variety of bibliographic databases and published between the beginning of the review period and the time of going to press. The bibliography has been grouped into topics that relate to the reviews in this issue.