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333749
Mitochondrial DNA Copy Number in Peripheral Blood and Melanoma Occurrence


Monday, November 2, 2015 : 8:48 a.m. - 9:06 a.m.

Jie Shen, PhD, Department of Epidemiology, MD Anderson Cancer Center, Houston, TX
Vancheswaran Gopalakrishnan, BDS, MPH, PhD-Candidate, Department of Surgical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX
Jeffrey Lee, BA, MD, Surgical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX
Shenying Fang, PhD, MD, Surgical Oncology - Research, The University of Texas MD Anderson Cancer Center, Houston, TX
Chad Huff, PhD, Epidemiology, The University of Texas MD Anderson Cancer Center, Houston, TX
Xifeng Wu, MD, MS, PhD, Epidemiology, The University of Texas MD Anderson Cancer Center, Houston, TX
Hua Zhao, PhD, Epidemiolgy, The University of Texas MD Anderson Cancer Center, HOUSTON, TX
Audio (mp3) recording Recorded Presentation (mp4)
Introduction

 Melanoma is the 5thmost common cancer in the U.S ,and is believed to have been diagnosed in 76000 new patients while accounting for approximately 9000 deaths during 2014. Mitochondrial DNA (mtDNA) is circular, maternally inherited, extra-chromosomal DNA. Variations in its copy number, in peripheral blood may be a marker for mitochondrial dysfunction, and has been implicated to be a risk modifier for various cancers. However, the relationship between mtDNA copy number and the occurrence of melanoma is yet to be clearly understood.

 Methods

 We evaluated the association between mtDNA copy number in peripheral blood and melanoma occurrence in a case-control study of 500 melanoma cases and 500 individually matched, unrelated, healthy controls.  All cases were Texas residents and were newly diagnosed, surgically treated or histopathologically confirmed melanoma patients seen between April 1994 and July 2013. All study subjects were given a structured self-administered questionnaire to collect demographic data, and data on known risk factors. The mtDNA copy number was measured using real- time PCR. OR’s and 95% C.I.’s were estimated using multivariate unconditional logistic regression.

 Results

 Overall, mean mtDNA copy number was statistically significantly higher among melanoma cases, when compared to healthy controls (1.15 vs 0.99, P<0.001).Further, increased mtDNA copy number was associated with a 1.45-fold increased occurrence of melanoma (95% CI: 1.12-1.97). In quartile analyses, ORs (95% CIs) for the 2nd, 3rd, and 4th quartile of mtDNA copy number were 1.73 (1.16-2.98), 1.98 (1.24-3.21), and 2.39 (1.53-3.42) respectively, when compared with the 1st quartile (p for trend < 0.001). In addition, statistically significant joint effects between mtDNA copy number and variables related to pigmentation and history of sunlight exposure were also observed.

 Conclusion

 This study supports a positive association between mtDNA copy number and melanoma occurrence that is independent of known melanoma risk factors such as pigmentation and history of sunlight exposure. Future studies are warranted to confirm these findings and to elucidate the biological role of mtDNA copy number in melanoma occurrence.

Learning Areas:

Basic medical science applied in public health
Epidemiology
Public health or related research

Learning Objectives:
Analyze the association between mtDNA copy number and melanoma occurrence. Evaluate a trend if any between increasing quartiles of mtDNA copy number and melanoma occurrence.

Keyword(s): Cancer, Genetics

Presenting author's disclosure statement:

Qualified on the content I am responsible for because: I am a Delta-Omega inductee and a PhD epidemiology candidate at UTSPH. I have been working with several melanoma research projects (including my masters thesis) that have been similar to this one. The projects have investigated a wide range of topics that are of interest in melanoma patients including cost effectiveness of genetic testing, the role of body temperature,the role of a pre-existing skin cancers and the influence of the microbiome.
Any relevant financial relationships? No

I agree to comply with the American Public Health Association Conflict of Interest and Commercial Support Guidelines, and to disclose to the participants any off-label or experimental uses of a commercial product or service discussed in my presentation.

Back to: 3034.0: Recent Findings in Cancer Epidemiology