Abstract：
BACKGROUND: Exposure to greenness has been shown to be beneficial to health, but few studies have examined the association between residential greenness and prostate cancer (PCa) risk. Our main objectives were to identify the determinants of residential greenness, and to investigate if residential greenness was associated with PCa risk in Singapore.
METHODS: The hospital-based case-control study was conducted between April 2007 and May 2009. The Singapore Prostate Cancer Study (SPCS) comprised 240 prostate cancer cases and 268 controls, whose demographics and residential address were collected using questionnaires. Residential greenness was measured by normalized difference vegetation index (NDVI) around the participants\' homes using a buffer size of 1 km. Determinants of NDVI were identified using a multivariable linear regression model. Logistic regression models were used to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) of associations between NDVI and PCa risk, adjusting for potential confounders.
RESULTS: Having a BMI within the second quartile, as compared to the lowest quartile, was associated with higher levels of NDVI (β-coefficient = 0.263; 95% CI = 0.040-0.485) after adjusting for covariates. Additionally, being widowed or separated, as compared to being married, was associated with lower levels of NDVI (β-coefficient = -0.393; 95% CI = -0.723, -0.063). An interquartile range (IQR) increase in NDVI was positively associated with prostate cancer risk OR = 1.45; 95% CI = 1.02-2.07). Stratified analysis by tumour grade and stage showed that higher NDVI was associated with higher risk of low grade PCa.
CONCLUSIONS: Our findings suggested that residential greenness was associated with higher risk of PCa in Singapore. Future studies on the quality and type of green spaces, as well as other factors of residential greenness, in association with PCa risk should be conducted to better understand this relationship.
METHODS: The hospital-based case-control study was conducted between April 2007 and May 2009. The Singapore Prostate Cancer Study (SPCS) comprised 240 prostate cancer cases and 268 controls, whose demographics and residential address were collected using questionnaires. Residential greenness was measured by normalized difference vegetation index (NDVI) around the participants\' homes using a buffer size of 1 km. Determinants of NDVI were identified using a multivariable linear regression model. Logistic regression models were used to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) of associations between NDVI and PCa risk, adjusting for potential confounders.
RESULTS: Having a BMI within the second quartile, as compared to the lowest quartile, was associated with higher levels of NDVI (β-coefficient = 0.263; 95% CI = 0.040-0.485) after adjusting for covariates. Additionally, being widowed or separated, as compared to being married, was associated with lower levels of NDVI (β-coefficient = -0.393; 95% CI = -0.723, -0.063). An interquartile range (IQR) increase in NDVI was positively associated with prostate cancer risk OR = 1.45; 95% CI = 1.02-2.07). Stratified analysis by tumour grade and stage showed that higher NDVI was associated with higher risk of low grade PCa.
CONCLUSIONS: Our findings suggested that residential greenness was associated with higher risk of PCa in Singapore. Future studies on the quality and type of green spaces, as well as other factors of residential greenness, in association with PCa risk should be conducted to better understand this relationship.
摘要：
背景：暴露于绿色已被证明对健康有益，但是很少有研究检查住宅绿色与前列腺癌（PCa）之间的关联。我们的主要目标是确定住宅绿色的决定因素，并调查新加坡的住宅绿色是否与PCa风险相关。
方法：以医院为基础的病例对照研究于2007年4月至2009年5月进行。新加坡前列腺癌研究（SPCS）包括240例前列腺癌病例和268例对照，他们的人口统计和居住地址是用问卷收集的。使用1km的缓冲区大小，通过参与者房屋周围的归一化植被指数（NDVI）来测量住宅的绿色。使用多变量线性回归模型确定NDVI的决定因素。使用Logistic回归模型计算NDVI与PCa风险之间关联的比值比(ORs)和95%置信区间(CIs),调整潜在的混杂因素。
结果：BMI在第二个四分位数内，与最低四分位数相比，在调整协变量后，与较高的NDVI水平相关(β系数=0.263；95%CI=0.040-0.485)。此外,丧偶或分居，与结婚相比，与NDVI水平降低相关(β系数=-0.393；95%CI=-0.723，-0.063)。NDVI四分位距（IQR）增加与前列腺癌风险呈正相关（PCa风险的比值比[OR]=1.45；95％CI=1.02-2.07）。按肿瘤分级和分期进行的分层分析表明，较高的NDVI与较高的低度PCa风险相关。
结论：我们的研究结果表明，新加坡的住宅绿色与PCa的高风险相关。未来对绿色空间质量和类型的研究，以及住宅绿色的其他因素，应进行与PCa风险相关的研究,以更好地理解这种关系.
方法：以医院为基础的病例对照研究于2007年4月至2009年5月进行。新加坡前列腺癌研究（SPCS）包括240例前列腺癌病例和268例对照，他们的人口统计和居住地址是用问卷收集的。使用1km的缓冲区大小，通过参与者房屋周围的归一化植被指数（NDVI）来测量住宅的绿色。使用多变量线性回归模型确定NDVI的决定因素。使用Logistic回归模型计算NDVI与PCa风险之间关联的比值比(ORs)和95%置信区间(CIs),调整潜在的混杂因素。
结果：BMI在第二个四分位数内，与最低四分位数相比，在调整协变量后，与较高的NDVI水平相关(β系数=0.263；95%CI=0.040-0.485)。此外,丧偶或分居，与结婚相比，与NDVI水平降低相关(β系数=-0.393；95%CI=-0.723，-0.063)。NDVI四分位距（IQR）增加与前列腺癌风险呈正相关（PCa风险的比值比[OR]=1.45；95％CI=1.02-2.07）。按肿瘤分级和分期进行的分层分析表明，较高的NDVI与较高的低度PCa风险相关。
结论：我们的研究结果表明，新加坡的住宅绿色与PCa的高风险相关。未来对绿色空间质量和类型的研究，以及住宅绿色的其他因素，应进行与PCa风险相关的研究,以更好地理解这种关系.
