P10: LYMPH NODE YIELD IS NOT A RELIABLE PROGNOSTIC MARKER IN ANTERIOR RESECTION AND ABDOMINOPERINEAL RESECTION FOLLOWING NEOADJUVANT THERAPY FOR RECTAL CANCER

Introduction

International guidelines recommend a minimum lymph node yield (LNY) of ≥12 for oncological resection in colorectal cancer (CRC). Neoadjuvant chemoradiotherapy (NACRT) decreases LNY, which questions its ability to provide accurate prognostic information. The consensus of this significance remains undetermined. This study aimed to investigate the significance of LNY on recurrence and survival following anterior resection and abdominoperineal resection with or without NACRT for rectal cancer.

Method

Prospectively collected data on patients diagnosed with rectal cancer in a tertiary referral centre was interrogated retrospectively. Patients were divided into primary surgery and NACRT groups. Univariable analysis was performed using Fisher's exact test, t-test, and x2 test, while multivariable analysis utilised a multiple regression model. Disease recurrence and survival was analysed with logrank test for Kaplan-Meier curves.

Result

148 patients were included [56.1% (n=83) receiving NACRT]. The median LNY of the primary surgery group was 14 [interquartile range (IQR) 11-19] and for the NACRT group was 12 (IQR 8-14) (p <0.001). Disease recurrence was similar in both primary surgery and NACRT groups. There was a significant decrease in overall mortality in NACRT patients (p = 0.03), but there was no significant difference observed in recurrence or mortality amongst LNYs of <8, 8-11, and ≥12.

Conclusion

LNY less than 12 was not a negative prognostic indicator following NACRT and surgery for rectal cancer.

Take-home message

A lymph node yield of less than 12 is not a negative prognostic indicator in rectal cancer patients who receive neoadjuvant chemotherapy.

A Comparative Study Between 20% Mannitol and 3% Hypertonic Saline for Brain Oedema Reduction during Elective Brain Tumour Surgery

Cerebral oedema is an important manifestation of brain tumour. The significant reduction of cerebral oedema can show rapid improvement of the patients. Hypertonic saline solution and mannitol both are commonly used for this action. It is now time to choose the better one. This was a prospective randomized comparative study designed to evaluate the efficacy of 3% hypertonic saline (NaCl) in reduction of brain oedema during brain tumour surgery and compare it with that of 20% Mannitol. The study was conducted in the department of Anaesthesiology, Combined Military Hospital, Dhaka, Bangladesh from July 2016 to December 2016. A total number of 47 patients for brain tumour surgery were selected. After screening 40 patients were finalized. Then the patients were divided into 2 equal groups 20 patients in each. Patients of Group A received 3% hypertonic saline and Group B 20% mannitol. Uniform anaesthetic technique applied for all patients, fixed surgeon/group of surgeons carried out the surgery. Heart rate and noninvasive blood pressure were monitored and kept with in ±20% baseline values different means. ETCO2 were kept in between 28-32mm of Hg by adjusting ventilator setting. Reduction of brain oedema was monitored by subjective assessment of surgeons using a 3 point scale of brain relaxation. The data were recorded in preformed data sheet. The results were tested by chi-square test to see their level of significance i.e. p value <0.05 was considered as significant. At the opening of dura, the number of brain conditions classified as soft, adequate and tight were statistically non-significant between groups. After 0.5 hour and 1.0 hour 10% patient's brain was tight in Group A whereas it was 35% and 40% in Group B respectively. Reduction of brain oedema or brain relaxation was significantly better in Group A compared to Group B (p<0.05). Urine output was higher with mannitol than hypertonic saline (p<0.05). Duration of ICU and hospital stay in both Group A and Group B were statistically similar (p>0.05). Compared to mannitol, hypertonic saline caused an increase in serum sodium concentration over time (p<0.05). From the available data, use of 20% mannitol and 3% hypertonic saline for brain oedema reduction, it is suggested that hypertonic saline significantly reduces the risk of tight brain and produce the brain more soft than mannitol during brain tumour surgery.

Changing trends in age and stage of colorectal cancer presentation in Ireland - From the nineties to noughties and beyond

BACKGROUND

Recent studies report incidence of colorectal (CRC) in younger adults (<50 years old) is increasing, and these patients are more likely to present with advanced disease. We performed a population-based analysis of these trends in an Irish population.

METHODS

A retrospective analysis was performed of all patients with histologically confirmed CRC in Ireland, using data from the National Cancer Registry of Ireland (NCRI) [1994-2012, inclusive]. Trends in age-adjusted CRC incidence and stage at presentation were tabulated. Total and average age-adjusted annual percentage change (APC) in CRC rates were calculated using regression analysis, with age adjusted to the European standard population for trend analysis.

RESULTS

A total of 39,528 cases were included. Throughout the entire study period the most common age of presentation was 70-79 years (32.5%, n = 12 829) with Stage II (27.5%, n = 10 851) CRC. Overall, an increase in incidence of CRC of 2.1% was observed. A significantly increased incidence in patients aged 20-29 years (APC = 9.17%; total change = 4.2%; p = 0.003) was identified from 1994 to 2012. Overall, in patients <50 years, the incidence of stage I colorectal cancer at presentation significantly reduced from 23.5% to 11.6% (p = 0.01). This was associated with a significant parallel rise in stage IV disease (11%-23%, p = 0.02) in this age group.

CONCLUSION

Increasing incidence of CRC in younger patient groups is observed in an Irish population, with an increase in advanced staged disease at presentation seen. Further studies should focus on identifying causality for this trend and identify potential targets for prevention going forward.

The prooxidant action of dietary antioxidants leading to cellular DNA breakage and anticancer effects: implications for chemotherapeutic action against cancer

Plant-derived dietary antioxidants have attracted considerable interest in recent past for their ability to induce apoptosis and regression of tumors in animal models. While it is believed that the antioxidant properties of these agents may contribute to lowering the risk of cancer induction by impeding oxidative injury to DNA, it could not account for apoptosis induction and chemotherapeutic observations. In this article, we show that dietary antioxidants can alternatively switch to a prooxidant action in the presence of transition metals such as copper. Such a prooxidant action leads to strand breaks in cellular DNA and growth inhibition in cancer cells. Further, the cellular DNA breakage and anticancer effects were found to be significantly enhanced in the presence of copper ions. Moreover, inhibition of antioxidant-induced DNA strand breaks and oxidative stress by Cu(I)-specific chelators bathocuproine and neocuproine demonstrated the role of endogenous copper in the induction of the prooxidant mechanism. Since it is well established that tissue, cellular, and serum copper levels are considerably elevated in various malignancies, such a prooxidant cytotoxic mechanism better explains the anticancer activity of dietary antioxidants against cancer cells.

Synthesis, spectroscopic investigations, antimicrobial and DNA binding studies of a new charge transfer complex of o-phenylenediamine with 3,5-dinitrosalicylic acid

A charge transfer complex of o-phenylenediamine (OPD) as donor with 3,5-dinitrosalicylic acid (DNSH) as acceptor, was synthesized and characterized by FTIR, (1)H NMR, (13)C NMR, mass spectroscopy, elemental analysis and X-ray crystallography. The structural investigations exhibit that the cation and anion are joined together by strong N(+)H⋯O(-) type hydrogen bonds and stoichiometry of CT complex was found to be 1:1. The CT (charge transfer) complex shows remarkable interaction with Calf thymus DNA, and the CT complex was also screened for its microbial activity such as antimicrobial and antifungal activities. A molecular frame work through H-bonding interactions via n→π(*) transitions between neighboring moieties is found which is responsible for high melting point of resulting CT complex. This has been attributed to the formation of 1:1 CT complex.

Gamma-amino butyric acid inhibits the nicotine-imposed stimulatory challenge in xenograft models of non-small cell lung carcinoma

Non-small cell lung carcinoma (NSCLC) is the leading type of lung cancer; smoking is a documented risk factor. Nicotinic acetylcholine receptor (nAChR)-mediated intracellular signaling in response to nicotine has recently been implicated in the growth regulation of NSCLC. In the current study nude mice carrying xenografts of the human lung NSCLC cell lines NCI-H322 or NCI-H441 were used as animal models. Nicotine administration and gamma aminobutyric acid (GABA) treatment lasted for 30 days. Catecholamines, cortisol, GABA, and cAMP were analyzed in blood and tumor tissues by immunoassays. Expression of nicotinic receptors and effector proteins in the xenografts was assessed by Western blotting. Our data indicate that nicotine stimulated the growth of NSCLC xenografts via modulation of nAChR upregulation and activation of cAMP signaling. The nicotine-treated group showed an enhanced level of stress neurotransmitters and second messenger cAMP in serum, blood cellular fraction, and xenograft tissues. Activation of critical proteins in the oncogenic pathway, including CREB, ERK, Akt, and Src, and upregulation of α-4 and α-7 subunits of nAChR provided mechanistic insight for the observed stimulatory effect of nicotine. Interestingly, GABA, being an antagonist to cAMP signaling, showed a promising intervention by reversing the stimulatory effect of nicotine on cancer growth and all signaling pathways. GABA has potential to lower the risk of NSCLC among smokers and could be used to enhance the clinical outcome of standard cancer intervention strategies.

Apogossypolone, derivative of gossypol, mobilizes endogenous copper in human peripheral lymphocytes leading to oxidative DNA breakage

Gossypol is a polyphenolic aldehyde that is produced in the cotton plant. Since long it has been reported to possess antiproliferative activity against a variety of cancer cell lines as well as tumor regression in animal models. However, the toxicity of gossypol does not permit it to be an effective antitumor agent. One of the derivatives of gossypol to show promising results is apogossypolone. For example, it has been shown to specifically target tumor growth in hepatocellular carcinoma xenograft in nude mice without causing any damage to normal tissue. Using human peripheral lymphocytes, in this paper we show that both gossypol and its semi-synthetic derivative apogossypolone cause oxidative DNA breakage in these cells through the mobilization of endogenous copper ions. Such cellular DNA breakage is inhibited by copper specific chelator but nor by iron or zinc chelating agents. Similar results are obtained with isolated nuclei indicating that chromatin bound copper is mobilized in this reaction. Further, apogossypolone showed enhanced DNA breakage and increased oxidative stress in whole lymphocytes as compared with gossypol indicating that this is possibly the result of greater permeability of apogossypolone. It is well established that tissue, cellular and serum copper levels are considerably elevated in various malignancies. Therefore, cancer cells may be subject to greater electron transfer between copper ions and gossypol/apogossypolone to generate reactive oxygen species responsible for DNA cleavage. This may account for the preferential cytotoxicity of apogossypolone towards tumor cells.

Catalytic therapy of cancer by ascorbic acid involves redox cycling of exogenous/endogenous copper ions and generation of reactive oxygen species

Catalytic therapy is a cancer treatment modality based on the generation of reactive oxygen species (ROS) through administration of ascorbate/medicinal herbal extracts and copper. It is known that antioxidants such as ascorbate also exhibit prooxidant activity in the presence of transition metals such as copper. Based on our work and that in the literature, in this review we propose a mechanism for the cytotoxic action of ascorbate against cancer cells. It involves redox cycling of exogenous/endogenous copper ions and the consequent generation of ROS leading to oxidative DNA breakage. Using human peripheral lymphocytes and the Comet assay, we have shown that ascorbic acid is able to cause oxidative breakage in cellular DNA. Such DNA degradation is inhibited by neocuproine (a Cu(I) sequestering agent) and scavengers of ROS indicating that the cellular DNA breakage involves the generation of Cu(I) and formation of ROS. Similar results are also obtained with plant polyphenol antioxidants that are important constituents of medicinal herbal extracts. Copper is an essential component of chromatin and can take part in redox reactions. It is well established that tissue, cellular and serum copper levels are considerably elevated in various malignancies. Therefore, cancer cells may be more subject to electron transfer between copper ions and ascorbate/plant polyphenols to generate ROS. In this review we cite evidence to indicate that in catalytic therapy cytotoxic action against cancer cells involves redox cycling of exogenous/endogenous copper ions.

DNA degradation by aqueous extract of Aloe vera in the presence of copper ions

The plant Aloe vera has long been used in medicine, as dietary supplements and for cosmetic purposes. Aloe vera extracts are a rich source of polyphenols, such as aloin and aloe emodin and have shown a wide range of pharmacological properties, including anti-inflammatory and anti-cancer properties. The bioactive component aloe emodin has been reported to induce apoptosis in various cancer cell lines. Many of the biological activities of Aloe vera have been attributed to its antioxidant properties. However, most plant-derived polyphenols that are also present in Aloe vera may exhibit pro-oxidant properties either alone or in the presence of transition metals, such as copper. Previous reports from this laboratory have implicated the pro-oxidant action as one of the mechanisms for their anti-cancer properties. In the present paper, we show that aqueous extract of Aloe vera is also able to cause DNA degradation in the presence of copper ions. Further, the extract is also able to reduce Cu(II) to Cu(I) and generate reactive oxygen species, such as superoxide anion and hydroxyl radicals in a dose-dependent manner, which correlates with ability of the extract to cause DNA breakage. Thus, the study shows that in addition to antioxidant activity, Aloe vera extract also possess pro-oxidant properties, leading to oxidative DNA breakage.

The antioxidant ascorbic acid mobilizes nuclear copper leading to a prooxidant breakage of cellular DNA: implications for chemotherapeutic action against cancer

PURPOSE

Ascorbic acid is an essential micronutrient and is considered to have an antioxidant function in living systems. For the past several decades, ascorbic acid has been the subject of considerable interest as an anticancer agent. Several studies have shown that ascorbic acid is cytotoxic to a variety of cancer cells, whereas normal cells are relatively resistant to such cytotoxic action. In this study, we propose a putative molecular mechanism that accounts for the preferential cytotoxicity of ascorbic acid against cancer cells.

METHODS

Standard and lysed version of alkaline single-cell gel electrophoresis (Comet assay); ferrous oxidation-xylenol orange (FOX) assay.

RESULTS

We show that ascorbic acid acts as a prooxidant and leads to oxidative DNA breakage in lymphocytes and lymphocyte nuclei. Scavengers of reactive oxygen species were able to inhibit ascorbic acid-induced DNA breakage, suggesting the involvement of reactive oxygen species in this reaction. We further show that such DNA breakage is inhibited by both iron and copper chelators in cells, whereas in nuclei, similar inhibition was achieved only by copper chelators, indicating an important role of chromatin-bound copper in the prooxidant cellular DNA breakage by ascorbic acid.

CONCLUSION

We propose that the copper-dependent cellular redox status is an important element in the cytotoxic action of ascorbic acid against cancer cells. It is well established that cellular copper levels are considerably elevated in various malignancies. Therefore, cancer cells may be more subject to electron transfer between copper and ascorbate to generate reactive oxygen species. In light of these observations and those in literature, in this paper we explain that the preferential cytotoxicity of ascorbic acid against cancer cells is the result of elevated copper levels in such cells. Further, this study identifies nuclear copper as a novel molecular target for cytotoxic action of ascorbic acid, which has implications for its chemotherapeutic properties against cancer.

Oxidative breakage of cellular DNA by plant polyphenols: a putative mechanism for anticancer properties

Plant polyphenols are important components of human diet and a number of them are considered to possess chemopreventive and therapeutic properties against cancer. They are recognized as naturally occurring antioxidants but also act as prooxidants catalyzing DNA degradation in the presence of transition metal ions such as copper. We have shown that several of these compounds are able to bind both DNA and Cu(II) forming a ternary complex. A redox reaction of the polyphenols and Cu(II) in the ternary complex may occur leading to the reduction of Cu(II) to Cu(I), whose reoxidation generates a variety of reactive oxygen species (ROS). We have further confirmed that the polyphenol-Cu(II) system is indeed capable of causing DNA degradation in cells such as lymphocytes. We have also shown that polyphenols alone (in the absence of added copper) are also capable of causing DNA breakage in cells. Neocuproine (a Cu(I) sequestering agent) inhibits such DNA degradation. It also inhibits the oxidative stress generated in lymphocytes indicating that the cellular DNA breakage involves the generation of Cu(I) and formation of ROS. It is well established that tissue, cellular and serum copper levels are considerably elevated in various malignancies. Therefore, cancer cells may be more subject to electron transfer between copper ions and polyphenols to generate ROS. Thus, our results are in support of our hypothesis that anticancer mechanism of plant polyphenols involves mobilization of endogenous copper possibly chromatin bound copper and the consequent prooxidant action.