J Breast Cancer.  2013 Jun;16(2):171-177. 10.4048/jbc.2013.16.2.171.

Sunlight Exposure and Breast Density: A Population-Based Study

• Wu SH
• Ho SC
• So E
• Lam TP
• Woo J
• Yuen PY
• Qin L
• Ku S

• KMID: 2286397
• DOI: http://doi.org/10.4048/jbc.2013.16.2.171

Abstract

PURPOSE
This study aims to assess the association of sunlight exposure with breast cancer risk, measured by the breast density assessed from Tabar'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 Tabar'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 (Tabar'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 Tabar'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.

Keyword

Breast neoplasms; Mammographic density; Sunlight; Vitamin D

MeSH Terms

Aged
Asian Continental Ancestry Group
Breast
Breast Neoplasms
Female
Humans
Logistic Models
Mammary Glands, Human
Odds Ratio
Solar System
Sunlight
Telephone
Vitamin D
Surveys and Questionnaires
Breast Neoplasms
Mammary Glands, Human
Vitamin D

Figure

• 

  Figure 1 Tabár patterns (I, II, & III and IV & V indicates low and high breast cancer risk) vs. mean lifetime total hours spent in the sun.

Reference

1. Cui Y, Rohan TE. Vitamin D, calcium, and breast cancer risk: a review. Cancer Epidemiol Biomarkers Prev. 2006; 15:1427–1437. PMID: 16896028.

2. Giovannucci E. The epidemiology of vitamin D and cancer incidence and mortality: a review (United States). Cancer Causes Control. 2005; 16:83–95. PMID: 15868450.

3. Ingraham BA, Bragdon B, Nohe A. Molecular basis of the potential of vitamin D to prevent cancer. Curr Med Res Opin. 2008; 24:139–149. PMID: 18034918.

4. Grant WB, Holick MF. Benefits and requirements of vitamin D for optimal health: a review. Altern Med Rev. 2005; 10:94–111. PMID: 15989379.

5. Reichel H, Koeffler HP, Norman AW. The role of the vitamin D endocrine system in health and disease. N Engl J Med. 1989; 320:980–991. PMID: 2648151.

6. Garland FC, Garland CF, Gorham ED, Young JF. Geographic variation in breast cancer mortality in the United States: a hypothesis involving exposure to solar radiation. Prev Med. 1990; 19:614–622. PMID: 2263572.

7. John EM, Schwartz GG, Dreon DM, Koo J. Vitamin D and breast cancer risk: the NHANES I Epidemiologic follow-up study, 1971-1975 to 1992. National Health and Nutrition Examination Survey. Cancer Epidemiol Biomarkers Prev. 1999; 8:399–406. PMID: 10350434.

8. Freedman DM, Chang SC, Falk RT, Purdue MP, Huang WY, McCarty CA, et al. Serum levels of vitamin D metabolites and breast cancer risk in the prostate, lung, colorectal, and ovarian cancer screening trial. Cancer Epidemiol Biomarkers Prev. 2008; 17:889–894. PMID: 18381472.

9. John EM, Schwartz GG, Koo J, Wang W, Ingles SA. Sun exposure, vitamin D receptor gene polymorphisms, and breast cancer risk in a multiethnic population. Am J Epidemiol. 2007; 166:1409–1419. PMID: 17934201.

10. Oza AM, Boyd NF. Mammographic parenchymal patterns: a marker of breast cancer risk. Epidemiol Rev. 1993; 15:196–208. PMID: 8405204.

11. Boyd NF, Lockwood GA, Byng JW, Tritchler DL, Yaffe MJ. Mammographic densities and breast cancer risk. Cancer Epidemiol Biomarkers Prev. 1998; 7:1133–1144. PMID: 9865433.

12. Jakes RW, Duffy SW, Ng FC, Gao F, Ng EH. Mammographic parenchymal patterns and risk of breast cancer at and after a prevalence screen in Singaporean women. Int J Epidemiol. 2000; 29:11–19. PMID: 10750598.

13. Gram IT, Funkhouser E, Tabár L. The Tabár classification of mammographic parenchymal patterns. Eur J Radiol. 1997; 24:131–136. PMID: 9097055.

14. Hong Kong Cancer Registry, Hospital Authority. 2012. Accessed May 24th, 2013. http://www3.ha.org.hk/cancereg/.

15. Woo J, Lam CW, Leung J, Lau WY, Lau E, Ling X, et al. Very high rates of vitamin D insufficiency in women of child-bearing age living in Beijing and Hong Kong. Br J Nutr. 2008; 99:1330–1334. PMID: 17961293.

16. Godar DE. UV doses worldwide. Photochem Photobiol. 2005; 81:736–749. PMID: 15819599.

17. Webb AR. Who, what, where and when-influences on cutaneous vitamin D synthesis. Prog Biophys Mol Biol. 2006; 92:17–25. PMID: 16766240.

18. McCarty CA. Sunlight exposure assessment: can we accurately assess vitamin D exposure from sunlight questionnaires? Am J Clin Nutr. 2008; 87:1097S–1101S. PMID: 18400741.

19. Knight JA, Lesosky M, Barnett H, Raboud JM, Vieth R. Vitamin D and reduced risk of breast cancer: a population-based case-control study. Cancer Epidemiol Biomarkers Prev. 2007; 16:422–429. PMID: 17372236.

20. Gilbert R, Metcalfe C, Oliver SE, Whiteman DC, Bain C, Ness A, et al. Life course sun exposure and risk of prostate cancer: population-based nested case-control study and meta-analysis. Int J Cancer. 2009; 125:1414–1423. PMID: 19444909.

21. Wu SH, Ho SC, Lam T. Validity and reproducibility of the Chinese lifetime sunlight exposure questionnaire. Scientific Report. 2013; In press.

22. Ginsburg OM, Martin LJ, Boyd NF. Mammographic density, lobular involution, and risk of breast cancer. Br J Cancer. 2008; 99:1369–1374. PMID: 18781174.

23. Vieth R. The pharmacology of vitamin D, including fortification strategies. In : Feldman D, Pike JW, Glorieux FH, editors. Vitamin D. 2nd ed. Amsterdam: Elsevier Academic Press;2005. p. 995–1015.

24. Holick MF. Environmental factors that influence the cutaneous production of vitamin D. Am J Clin Nutr. 1995; 61(3 Suppl):638S–645S. PMID: 7879731.

25. Webb AR, Pilbeam C, Hanafin N, Holick MF. An evaluation of the relative contributions of exposure to sunlight and of diet to the circulating concentrations of 25-hydroxyvitamin D in an elderly nursing home population in Boston. Am J Clin Nutr. 1990; 51:1075–1081. PMID: 2349922.

26. Jacques PF, Felson DT, Tucker KL, Mahnken B, Wilson PW, Rosenberg IH, et al. Plasma 25-hydroxyvitamin D and its determinants in an elderly population sample. Am J Clin Nutr. 1997; 66:929–936. PMID: 9322570.

27. English DR, Armstrong BK, Kricker A, Fleming C. Sunlight and cancer. Cancer Causes Control. 1997; 8:271–283. PMID: 9498892.

28. van der Mei IA, Blizzard L, Ponsonby AL, Dwyer T. Validity and reliability of adult recall of past sun exposure in a case-control study of multiple sclerosis. Cancer Epidemiol Biomarkers Prev. 2006; 15:1538–1544. PMID: 16896046.

29. van der Rhee HJ, de Vries E, Coebergh JW. Does sunlight prevent cancer? A systematic review. Eur J Cancer. 2006; 42:2222–2232. PMID: 16904314.