Sunlight exposure and breast density: A population-based study

Sheng Hui Wu, Suzanne C. Ho, Edwin So, Tsz ping Lam, Jean Woo, P. Y. Yuen, Ling Qin, Susanna Ku

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


Purpose: This study aims to assess the association of sunlight exposure with breast cancer risk, measured by the breast density assessed from Tabár's mammographic pattern in Chinese women. Methods: A total of 676 premenopausal women were recruited to participate in this study, in which 650 completed a validated sunlight exposure questionnaire via telephone. The mammograms were classified according to Tabár's classification for parenchyma, and patterns IV & V and I, II & III indicated respectively high and low risk mammographic patterns for breast cancer. The odds ratios (OR) and 95% confidence intervals (CIs) for sun exposure-related variables were estimated using unconditional logistic regression with adjustment for potential confounders. Results: Among 646 participants, women with high breast cancer risk (Tabár's patterns IV &V) had less hours spent in the sun than those with low risk (I, II & III) at any age stage. A higher level of sunlight exposure was associated with a significantly lower risk having high risk Tabár's pattern. Women aged 40 to 44 years who were in the highest tertile of lifetime total hours spent in the sun had a multi-adjusted OR of 0.41 (95% CI, 0.18-0.92; p for trend=0.03) compared with those in the lowest tertile (>2.19 hr/day vs. <1.32 hr/day). For hours spent in the sun across the ages of 6 to 12 years, the comparable OR was 0.37 (95% CI, 0.15-0.91; p for trend=0.03). Conclusion: These findings suggest that higher sunlight exposure is related to a lower risk of having high risk breast density pattern in premenopausal women. Our results also suggest the most relevant period of exposure is during earlier life.

Original languageEnglish (US)
Pages (from-to)171-177
Number of pages7
JournalJournal of Breast Cancer
Issue number2
StatePublished - Jun 2013
Externally publishedYes


  • Breast neoplasms
  • Mammographic density
  • Sunlight
  • Vitamin D

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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