Periodontal disease may be associated with increased breast cancer risk, but studies have not considered invasive breast cancer and ductal carcinoma in situ (DCIS) separately in the same population. We assessed the relationship between periodontal disease and breast cancer in a large prospective cohort study. The Sister Study followed women without prior breast cancer ages 35 to 74 years from 2003 to 2017 (N = 49,968). Baseline periodontal disease was self-reported, and incident breast cancer was ascertained over a mean follow-up of 9.3 years. We estimated hazard ratios (HR) and 95% confidence intervals (CI) using Cox proportional hazards regression, adjusting for multiple potential confounders, including smoking status. Heterogeneity in risk for invasive breast cancer versus DCIS was also estimated. About 22% of participants reported a history of periodontal disease at baseline. A total of 3,339 incident breast cancers (2,607 invasive breast cancer, 732 DCIS) were identified. There was no clear association between periodontal disease and overall breast cancer risk (HR = 1.02; 95% CI, 0.94–1.11). However, we observed a nonstatistically significant suggestive increased risk of invasive breast cancer (HR = 1.07; 95% CI, 0.97–1.17) and decreased risk of DCIS (HR = 0.86; 95% CI, 0.72–1.04) associated with periodontal disease, with evidence for heterogeneity in the risk associations (relative HR for invasive breast cancer versus DCIS = 1.24; 95% CI, 1.01–1.52). A case-only analysis for etiologic heterogeneity confirmed this difference. We observed no clear association between periodontal disease and overall breast cancer risk. The heterogeneity in risk associations for invasive breast cancer versus DCIS warrants further exploration.

中文翻译：

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前瞻性队列研究中牙周病与乳腺癌之间的关联

牙周病可能与乳腺癌风险增加有关，但研究并未分别考虑同一人群中的浸润性乳腺癌和导管原位癌 (DCIS)。我们在一项大型前瞻性队列研究中评估了牙周病与乳腺癌之间的关系。该姐妹研究从 2003 年到 2017 年对 35 岁至 74 岁之前没有患乳腺癌的女性进行了追踪（N = 49,968）。基线牙周病由患者自行报告，乳腺癌的发生是在平均 9.3 年的随访中确定的。我们使用 Cox 比例风险回归估计了风险比 (HR) 和 95% 置信区间 (CI)，并调整了多个潜在的混杂因素，包括吸烟状况。还评估了浸润性乳腺癌与 DCIS 风险的异质性。约 22% 的参与者报告基线时有牙周病史。总共鉴定出 3,339 例乳腺癌（2,607 例浸润性乳腺癌，732 例 DCIS）。牙周病与总体乳腺癌风险之间没有明确的关联（HR = 1.02；95% CI，0.94-1.11）。然而，我们观察到与牙周病相关的非统计学意义的浸润性乳腺癌风险增加（HR = 1.07；95% CI，0.97–1.17）和 DCIS 风险降低（HR = 0.86；95% CI，0.72–1.04）。有证据表明风险关联存在异质性（浸润性乳腺癌与 DCIS 的相对 HR = 1.24；95% CI，1.01–1.52）。病因异质性的仅病例分析证实了这种差异。我们观察到牙周病与总体乳腺癌风险之间没有明确的关联。浸润性乳腺癌与 DCIS 风险关联的异质性值得进一步探索。