No evidence for differences in DNA damage assessed before and after a cancer diagnosis.

نویسندگان

  • Parveen Bhatti
  • Alice J Sigurdson
  • Cynthia B Thomas
  • Allison Iwan
  • Bruce H Alexander
  • Diane Kampa
  • Laura Bowen
  • Michele Morin Doody
  • Irene M Jones
چکیده

The overwhelming majority of studies that have found increased cancer risk associated with functional deficits in DNA repair used a case-control design, in which measurements were made after cancer diagnosis. However, there are concerns about whether the cancer itself or cancer treatment affected the conclusions (reverse causation bias). We assessed the effect of cancer diagnosis among 26 breast cancer controls who had blood collected during 2001 to 2003 and again in 2005 to 2006 after being diagnosed with cancer. Using the alkaline comet assay, we quantified DNA damage in untreated lymphoblastoid cell lines. Comet distributed moment, olive tail moment, percentage of DNA in tail, and comet tail length were summarized as the geometric mean of 100 cells. For comet distributed moment, olive tail moment, tail DNA, and tail length, the proportions of women with before diagnosis values higher than after diagnosis were 65%, 50%, 50%, and 46%, respectively. We found no significant differences in the before or after diagnosis mean comet values. Median cut-points were determined from the before diagnosis distribution, and we used conditional logistic regression to calculate odds ratios (OR) and upper 95% bounds of the confidence intervals. ORs ranged from 0.6 to 0.9 with upper confidence interval bounds of 1.9 and 2.6, meaning biased ORs above 2.6 are unlikely. We found no evidence that reverse causation bias is an important concern in case-control studies using the comet assay applied to cell lines collected after cancer diagnosis. More work is needed to characterize the effect of cancer diagnosis on other phenotypic assays.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Radiosensitivity and Repair Kinetics of Gamma-Irradiated Leukocytes from Sporadic Prostate Cancer Patients and Healthy Individuals Assessed by Alkaline Comet Assay

Background: Impaired DNA repair mechanism is one of the main causes of tumor genesis. Study of intrinsic radiosensitivity of cancer patients in a non-target tissue (e.g. peripheral blood) might show the extent of DNA repair deficiency of cells in affected individuals and might be used a predictor of cancer predisposition. Methods: Initial radiation-induced DNA damage (ratio of Tail DNA/Head DN...

متن کامل

Sperm DNA damage in mice irradiated with various doses of X-rays alone or in combination with actinomycin D or bleomycin sulfate: an in vivo study

Background: DNA damage in male germ cells due to exposure to environmental and manmade physico-chemical genotoxic agents is considered as the main cause of male infertility. The aim of this study was to evaluate the effects of combined modalities (radiotherapy and chemotherapy) routinely used for cancer treatment on mouse sperm chromatin in vivo. Materials and Methods: Forty-eight mice were div...

متن کامل

An Increased Genotoxic Risk in Lymphocytes from Phototherapy-Treated Hyperbilirubinemic Neonates

Background: Phototherapy is believed to be a safe method for the management of hyperbilirubinemia. However, there are some controversial issues regarding the genotoxic effects of phototherapy on DNA. The aim of this study was to investigate morphologically both phototherapy-induced DNA double-strand breaks (DSBs) and apoptosis in lymphocytes derived from jaundiced and non-jaundiced neonates. Me...

متن کامل

DNA Damage in Leukocytes from Fanconi Anemia (FA) Patients and Heterozygotes Induced by Mitomycin C and Ionizing Radiation as Assessed by the Comet and Comet-FISH Assay

Background: Lymphocytes of Fanconi anemia (FA) show an increased sensitivity to the alkylating agents such as mitomycin C (MMC), but their responses to gamma-irradiation is controversial. The extent of DNA damage in leukocytes of FA patients following irradiation and MMC treatment was studied at cellular and single chromosome level. Methods: DNA damage induced by gamma-rays and MMC was measure...

متن کامل

Are there Relationships between the VDR-FokI Polymorphism and Vitamin D and the Insulin Resistance in Non-melanoma Skin Cancer (NMSC) Patients? A Protocol for Case-control Studies

Background and Objectives: Evidence indicate relationships between the sunlight exposure, vitamin D status and non-melanoma skin cancer (NMSC) risk. Vitamin D receptor (VDR) polymorphisms have been linked to metabolic changes in insulin resistance and various cancers. The purpose of this study is to investigate relationships between the sunlight exposure and the NMSC risk. Furthermore, relation...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:
  • Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology

دوره 17 4  شماره 

صفحات  -

تاریخ انتشار 2008