乳房X光检查结果假阳性很常见。然而，假阳性结果后的长期结果仍不清楚。检查假阳性乳房X光检查结果后的长期结果，并调查假阳性乳房X光检查结果与癌症的关联是否因基线特征、肿瘤特征而异，以及自假阳性结果以来的时间。这项基于人群的匹配队列研究于 1991 年 1 月 1 日至 2020 年 3 月 31 日在瑞典进行。其中包括 1991 年期间首次收到假阳性乳房 X 光检查结果的 45213 名女性2017 年和 452130 名对照在年龄、乳房 X 光检查日历年份和筛查历史上匹配（之前没有假阳性结果）。该研究还纳入了 1113 名具有假阳性结果的女性和 11130 名匹配的对照，这些对照组的信息来自卡罗林斯卡乳房 X 线摄影项目乳腺癌风险预测研究的乳房 X 线摄影乳腺密度信息。统计分析于 2022 年 4 月至 2023 年 2 月进行。乳房 X 光检查结果假阳性。乳腺癌发病率和死亡率。研究队列包括 497343 名女性（中位年龄，52 岁 [IQR，42-59 岁]）。有假阳性结果的女性 20 年乳腺癌累积发病率为 11.3%（95% CI，10.7%-11.9%），而没有假阳性结果的女性则为 7.3%（95% CI，7.2%-7.5%）。调整后的风险比 (HR) 为 1.61 (95% CI, 1.54-1.68)。检查时年龄为 60 至 75 岁的女性相应的 HR 较高（HR，2.02；95% CI，1.80-2.26），而乳房 X 光检查乳腺密度较低的女性（HR，4.65；95% CI，2.61-8.29）则相应的 HR 较高。此外，召回时接受活检的女性（HR，1.77；95% CI，1.63-1.92）患乳腺癌的风险高于未接受活检的女性（HR，1.51；95% CI，1.43-1.60）。假阳性结果后的癌症更有可能在假阳性结果的同侧检测到（HR，1.92；95% CI，1.81-2.04），并且在随访的前 4 年中更常见（前 2 年 HR，2.57；95% CI，2.33-2.85；>2 至 4 年 HR，1.93；95% CI，1.76-2.12）。不同肿瘤特征没有发现统计学差异（除了较大的肿瘤尺寸）。此外，与乳腺癌风险增加相关，具有假阳性结果的女性的乳腺癌死亡率比没有假阳性结果的女性高 84%（HR，1.84；95% CI，1.57-2.15）。乳房X光检查结果假阳性后患乳腺癌的风险因个体特征和随访情况而异。这些发现可用于在出现假阳性结果后进行个体化的基于风险的乳腺癌筛查。

False-positive mammography results are common. However, long-term outcomes after a false-positive result remain unclear.To examine long-term outcomes after a false-positive mammography result and to investigate whether the association of a false-positive mammography result with cancer differs by baseline characteristics, tumor characteristics, and time since the false-positive result.This population-based, matched cohort study was conducted in Sweden from January 1, 1991, to March 31, 2020. It included 45 213 women who received a first false-positive mammography result between 1991 and 2017 and 452 130 controls matched on age, calendar year of mammography, and screening history (no previous false-positive result). The study also included 1113 women with a false-positive result and 11 130 matched controls with information on mammographic breast density from the Karolinska Mammography Project for Risk Prediction of Breast Cancer study. Statistical analysis was performed from April 2022 to February 2023.A false-positive mammography result.Breast cancer incidence and mortality.The study cohort included 497 343 women (median age, 52 years [IQR, 42-59 years]). The 20-year cumulative incidence of breast cancer was 11.3% (95% CI, 10.7%-11.9%) among women with a false-positive result vs 7.3% (95% CI, 7.2%-7.5%) among those without, with an adjusted hazard ratio (HR) of 1.61 (95% CI, 1.54-1.68). The corresponding HRs were higher among women aged 60 to 75 years at the examination (HR, 2.02; 95% CI, 1.80-2.26) and those with lower mammographic breast density (HR, 4.65; 95% CI, 2.61-8.29). In addition, breast cancer risk was higher for women who underwent a biopsy at the recall (HR, 1.77; 95% CI, 1.63-1.92) than for those without a biopsy (HR, 1.51; 95% CI, 1.43-1.60). Cancers after a false-positive result were more likely to be detected on the ipsilateral side of the false-positive result (HR, 1.92; 95% CI, 1.81-2.04) and were more common during the first 4 years of follow-up (HR, 2.57; 95% CI, 2.33-2.85 during the first 2 years; HR, 1.93; 95% CI, 1.76-2.12 at >2 to 4 years). No statistical difference was found for different tumor characteristics (except for larger tumor size). Furthermore, associated with the increased risk of breast cancer, women with a false-positive result had an 84% higher rate of breast cancer death than those without (HR, 1.84; 95% CI, 1.57-2.15).This study suggests that the risk of developing breast cancer after a false-positive mammography result differs by individual characteristics and follow-up. These findings can be used to develop individualized risk-based breast cancer screening after a false-positive result.