Reasons for delay in timely administration of adjuvant chemotherapy for patients with stage III colon cancer: a multicentre cohort study from the McGill University Department of Oncology

PURPOSE

Adjuvant chemotherapy within 56 or 84 days following curative resection is globally accepted as the standard of care for stage III colon cancer as it has been associated with improved overall survival. Initiation of adjuvant chemotherapy within this time frame is therefore recommended by clinical practice guidelines, including the European Society for Medical Oncology. The objective of this study was to evaluate adherence to these clinical practice guidelines for patients with stage III colon cancer across the Rossy Cancer Network (RCN); a partnership of McGill University's Faculty of Medicine, McGill University Health Centre, Jewish General Hospital and St Mary's Hospital Center.

PATIENTS AND METHODS

187 patients who had been diagnosed with stage III colon cancer and received adjuvant chemotherapy within the RCN partner hospitals from 2012 to 2015 were included. Patient and treatment information was retrospectively determined by chart review. Χ² and Wilcoxon rank-sum tests were used to measure associations and a multivariate Cox regression model was used to determine risk factors contributing to delays in administration of adjuvant chemotherapy.

RESULTS

The median turnaround time between surgery and adjuvant chemotherapy was 69 days. Importantly, only 27% of patients met the 56-day target, and 71% met the 84-day target. Increasing age, having more than one surgical complication and being diagnosed between 2013-2014 and 2014-2015 reduced the likelihood that patients met these targets. Furthermore, delays were observed at most intervals from surgery to first adjuvant chemotherapy treatment.

CONCLUSION

Our study found that within these academic hospital settings, 27% of patients met the 56-day target, and 71% met the 84-day target. Delays were associated with hospital, surgeon and patient-related factors. Initiatives in quality improvement are needed in order to improve adherence to recommended treatment guidelines for prompt administration of adjuvant chemotherapy for stage III colon cancer.

Metformin reduces endogenous reactive oxygen species and associated DNA damage

Pharmacoepidemiologic studies provide evidence that use of metformin, a drug commonly prescribed for type II diabetes, is associated with a substantial reduction in cancer risk. Experimental models show that metformin inhibits the growth of certain neoplasms by cell autonomous mechanisms such as activation of AMP kinase with secondary inhibition of protein synthesis or by an indirect mechanism involving reduction in gluconeogenesis leading to a decline in insulin levels and reduced proliferation of insulin-responsive cancers. Here, we show that metformin attenuates paraquat-induced elevations in reactive oxygen species (ROS), and related DNA damage and mutations, but has no effect on similar changes induced by H(2)0(2), indicating a reduction in endogenous ROS production. Importantly, metformin also inhibited Ras-induced ROS production and DNA damage. Our results reveal previously unrecognized inhibitory effects of metformin on ROS production and somatic cell mutation, providing a novel mechanism for the reduction in cancer risk reported to be associated with exposure to this drug.

Abstract LB-100: Optimal modulation of DNA repair in CLL therapy

Resistance to chlorambucil (CLB) in chronic lymphocytic leukemia (CLL) can occur as a consequence of increased DNA repair including c-abl stimulated Rad-51 related homologous recombinational repair (HRR) and DNA-PK related nonhomologous endjoining (NHEJ).

Recent reports suggest that the nonreceptor tyrosine kinase c-abl plays an important role in CLL. In particular, we have previously demonstrated that imatinib inhibition of c-abl or NU7026 inhibition of DNA-PK in CLL lymphocytes results in sensitization to CLB in most samples. Here we report that nilotinib, a superpotent (20-30 fold greater than niltinib) inhibitor of c-abl is more efficacious than imatinib in sensitizing CLL lymphocytes to CLB in the majority of the CLL lymphocyte samples associated with a greater nilotinib related inhibition of c-abl autophosporylation, increased apoptosis and decreased repair of CLB-induced DNA damage (increased activated H2AX).

Furthermore, in CLL samples in which c-abl was inhibited by either inhibitor, there was an increased activation of DNA-PK. Utilizing NU7026, a specific inhibitor of DNA-PK, with nilotinib or imatinib resulted in further sensitization to CLB but there was a greater sensitization to CLB with nilotinib than imatinib. These results suggest: (1) a more potent inhibition of c-abl is more efficacious in sensitizing CLL lymphocytes to CLB, (2) inhibition of c-abl results in a compensatory increase in DNA-PK and (3) inhibiting both DNA repair systems optimally sensitizes CLL lymphocytes to CLB, an effect which is most pronounced with the more potent c-abl inhibitor, nilotinib.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-100.

Abstract A188: Proapoptotic versus prosurvival function of the MAP kinase p38 induced by HDAC inhibitor in hematological malignant cells

Histone deacetylase inhibitors (HDACi) have recently emerged as promising anticancer agents. However, the mechanisms by which HDAC inhibitors arrest proliferation and induce apoptosis in tumor cells is far from clear. Activation of the stress MAP kinases and induction of DNA damage by different HDACi have been reported, however, the potential role of the MAP kinase p38 in the antitumor activity of these drugs has not been described. P38 is known to be activated independently or downstream of DNA damage. The purpose of this study was to elucidate the mechanisms by which the HDACi vorinostat (Zolinza®) triggers apoptosis in haematological malignant cells.

We show that DNA damage as well as activation of p38 occurs relatively early in acute myeloid leukemia (AML) cell lines after treatment with vorinostat. Using comet assays, we detected direct evidence of early DNA damage and western blotting revealed induction of the DNA damage response proteins ATM and Chk2. We performed cell cycle analysis, and observed within the vorinostat-treated AML cell population, cells exiting G1 and accumulating in the G2-M phase of the cell cycle, where they subsequently underwent apoptosis. Notably, downregulation of p38 by shRNA or inhibition of p38 and β activity by the inhibitor SB203580 significantly decreased both G2-M accumulation and apoptosis induced by vorinostat, indicating a pro-apoptotic p38 function.

Interestingly, several other HDACi tested all induced p38 activation but, depending on the HDACi, this activation was found to be either pro or antiapoptotic. The short-chain fatty acid sodium butyrate (NaB) requires p38 for induction of apoptosis, like vorinostat. On the other hand, LBH589, from the structural class encompassing vorinostat, does not depend on p38 for induction of apoptosis. Furthermore, p38 serves as a pro-survival signal when induced by the benzimide MGCD0103.

In conclusion, we have shown that vorinostat-induced apoptosis in AML cells is preceded by generation of DNA damage and accumulation of cells in the G2-M phase of the cell cycle. Further, G2-M arrest and apoptosis induction (but not DNA damage) by vorinostat requires activation of the p38 MAP kinase, which is not the case for all HDACi. Therefore, a better understanding of the role of p38 MAPK in the action of specific HDACi may help in the development of rational combination regimes including these targeted agents.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A188.

[Clinical scientific research with ionizing radiation in Italy. The standards-setting and legal aspects]

INTRODUCTION

The paper reviews the laws that regulate the clinical scientific research with ionizing radiations in Italy. Although recent (all introduced after 1990), the laws are a maze of rules sometimes contradictory and unclear, with frequent cross-references which make them difficult to disentangle. The aim of the paper is to provide the researcher with a technical and legal guide to find his/her way in the labyrinth of rules, and to constitute a basis for a possible future rationalization of the regulations.

MATERIALS AND METHODS

The contents of the article n. 108 of the law by decree 230/1995 and of the Minister's Decree 21/11/1997 together with the ICRP 62 (introduced in Italy by the Minister's Decree 21/11/1997) are extensively reviewed. The authors stress the fact that these laws apply only to prospective, but not to retrospective studies. The procedure to obtain ministerial authorization of the research project is illustrated, together with the possibility of a bureaucratic shortcut whereby the ethical committee states that the project conforms to ICRP 62. Special attention is paid to the cases of contrast between the ICRP 62 and previously promulgated laws: dose thresholds in non-therapeutic research, research on pregnant women or in child-bearing age and the issue of the preliminary assessment of new radiopharmaceuticals on monkeys (recommended by ICRP 62 but strongly restricted by the law by decree 116/1992). As for studies with radiopharmaceuticals, the problem of the double authorization required by the Minister's Decree 21/11/1997 and by the memorandum 10/07/1997, n. 8 of the Ministry of Health is also discussed.

DISCUSSION AND CONCLUSIONS

The authors express the opinion that the Minister's Decree 21/11/1997, together with ICRP 62, render invalid all previous rules and regulations which contrast with them. The Minister's Decree 21/11/1997 and ICRP 62 are practical and exhaustive and offer the researchers and ethical committees precise and reliable guidelines. The paper aims to offer a contribution for the rationalization of the rules that regulate the field. To this regard, an accurate design of the future regulations, reflecting Euratom Directive 43/97 is expected by May 13, 2000. The authors' conclusion is that laws must regulate, not strangulate, clinical scientific research with ionizing radiations: incongruities, uncertainties and bureaucratic excesses must be corrected.