Prediagnosis leukocyte telomere length and risk of ovarian cancer

• Introduction: Ovarian cancer is characterized by substantial genomic instability. Telomeres, which protect the physical integrity of chromosomes, are shortened by each cell division, and evidence supports that longer telomeres may reduce genomic instability. While retrospective studies generally support an inverse association of telomere length and ovarian cancer risk, the measures of telomere length after diagnosis may be influenced by treatment. Therefore, we examined the relationship between leukocyte telomere length (LTL) assessed prior to diagnosis and risk of ovarian cancer in three prospective studies. Methods: We used buffy coat samples collected from healthy participants in the Nurses' Health Study (NHS), NHSII, and the Northern Sweden Health and Disease Study (NSHDS). Women who later developed ovarian cancer were matched to one or two controls on age, menopausal status, and date of blood collection. LTL was assessed using quantitative PCR-based assays in 5 batches with coefficients of variation of 10-15%. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using conditional logistic regression, based on study-specific quartiles in controls, for each study separately. We used fixed-effects models for meta-analysis. Multivariate models adjusted for oral contraceptive use, tubal ligation, family history of ovarian cancer, parity, smoking status, and body mass index. Results: In total, there were 487 cases and 810 controls across the three studies. The mean age at blood collection ranged from 45 (NHSII) to 57 (NHS) years. In unadjusted and multivariate models, we observed a suggestion of an inverse association between LTL and ovarian cancer risk in each study, although none of the trend tests were statistically significant. In a meta-analysis of the multivariate adjusted models, women in the longest versus shortest quartile of LTL had a non-significant 26% lower risk of ovarian cancer (OR=0.74; 95%CI=0.49-1.12; p-trend=0.33). Conclusion: In this first prospective study of telomere length and ovarian cancer risk, we observed that longer leukocyte telomere length was suggestively associated with lower ovarian cancer risk. Given that serous tumors are more likely to exhibit genomic instability, we are currently evaluating the association for this subtype as well as conducting pooled analyses with common quartile cut points across studies.

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MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Cancer och onkologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Cancer and Oncology (hsv//eng)

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