Parity and thyroid cancer risk: a meta-analysis of epidemiological studies.
Parity and thyroid cancer risk: a meta-analysis of epidemiological studies.
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作者：
Zhu J;Zhu X;Tu C;Li YY;Qian KQ;Jiang C;Feng TB;Li C;Liu GJ;Wu L
虽然观察性研究已经评估了胎次与甲状腺癌风险之间的关系，但研究结果并不一致。为了定量评估相关性，我们进行了系统回顾和荟萃分析。PubMed和Embase的检索截止到2015年1月。评估胎次与甲状腺癌风险之间关系的前瞻性或病例对照研究被纳入研究。我们使用固定效应模型来汇总风险估计。通过文献检索，我们确定了10项前瞻性研究、12项病例对照研究和1项汇总分析，共纳入14项病例对照研究，共纳入8860例患者。这些研究的方法学质量尚可。合并分析表明胎次与甲状腺癌风险之间存在显著关联（已产与未产的RR: 1.09, 95% CI 1.03‐1.15;I2=33.4%）。基于研究设计、地点、研究质量、对照类型和混杂因素调整，几乎所有亚组分析的层次都存在正相关，尽管在某些层次没有检测到统计学显著性。通过评估胎次数，我们发现胎次数为2的与未产的和胎次数为3的与未产的均表现出显著的正相关（RR=1.11, 95% CI 1.01‐1.22;I2=31.1%； RR=1.16, 95% CI 1.01‐1.33;I2=19.6%）。剂量-反应分析表明，胎次数与甲状腺癌风险之间既不是非线性关系，也不是线性关系。总之，本荟萃分析提示女性胎次与甲状腺癌风险之间存在潜在关联。然而，缺乏剂量-反应关系的检测表明，需要进一步的研究来更好地了解这种关系。
Although observational studies have assessed the relationship between parity and thyroid cancer risk, the findings are inconsistent. To quantitatively assess the association, we conducted a systematic review and meta‐analysis. PubMed and Embase were searched up to January 2015. Prospective or case–control studies that evaluated the association between parity and thyroid cancer risk were included. We used the fixed‐effects model to pool risk estimates. After literature search, 10 prospective studies, 12 case‐control studies and 1 pooled analysis of 14 case‐control studies including 8860 patients were identified. The studies had fair methodological quality. Pooled analysis suggested that there was a significant association between parity and risk of thyroid cancer (RR for parous versus nulliparous: 1.09, 95% CI 1.03‐1.15; I2=33.4%). The positive association persisted in almost all strata of subgroup analyses based on study design, location, study quality, type of controls, and confounder adjustment, although in some strata statistical significance was not detected. By evaluating the number of parity, we identified that both parity number of 2 versus nulliparous and parity number of 3 versus nulliparous demonstrated significant positive associations (RR=1.11, 95% CI 1.01‐1.22; I2=31.1% and RR=1.16, 95% CI 1.01‐1.33; I2=19.6% respectively). The dose‐response analysis suggested neither a non‐linear nor linear relationship between the number of parity and thyroid cancer risk. In conclusion, this meta‐analysis suggests a potential association between parity and risk of thyroid cancer in females. However, the lack of detection of a dose‐response relationship suggests that further studies are needed to better understand the relationship.