在曾接受乳腺癌治疗的女性中，第二个乳腺癌的发生和时间对监测有影响。作者在乳腺癌监测协会中研究了第二个乳腺癌的时间和原发性癌症雌激素受体（ER）状态。从2000年至2017年，在六个乳腺癌监测协会登记处确定了美国癌症联合委员会一至三期乳腺癌的女性。在原发乳腺癌诊断时收集了人口统计学资料、ER状态和治疗方法。第二个乳腺癌事件包括原发诊断后六个月以上诊断的同侧或对侧乳腺癌。作者在癌症诊断后1至5年与6至10年内按原发性癌症ER状态检查了累积发病率和第二乳腺癌率。10年后，ER阴性疾病的累积第二乳腺癌发生率为11.8%（95％置信区间[CI]为10.7％-13.1％），ER阳性疾病为7.5%（95％ CI为7.0％-8.0％）。在初次检查后的前5年内，ER阴性癌症的第二个乳腺癌发生率比ER阳性癌症高（每1000个人年16.0 [PY]; 95％ CI为14.2-17.9每1000PY;相比之下，每1000PY7.8 [PY]; 95％ CI为7.3-8.4每1000PY）。 5年后，ER阴性与ER阳性乳腺癌女性的第二乳腺癌发生率相似（每1000 PY12.1; 95％ CI为9.9-14.7; vs.每1000 PY9.3; 95％ CI为8.4-10.3每1000PY）。 原发性ER阴性乳腺肿瘤与第二个乳腺癌的风险比ER阳性肿瘤高，特别是在诊断后的前5年。需要进一步研究以检查更密集监测的潜在效益，针对这些女性在早期诊断后的时期。©2023美国癌症协会。

In women with previously treated breast cancer, occurrence and timing of second breast cancers have implications for surveillance. The authors examined the timing of second breast cancers by primary cancer estrogen receptor (ER) status in the Breast Cancer Surveillance Consortium.Women who were diagnosed with American Joint Commission on Cancer stage I-III breast cancer were identified within six Breast Cancer Surveillance Consortium registries from 2000 to 2017. Characteristics collected at primary breast cancer diagnosis included demographics, ER status, and treatment. Second breast cancer events included subsequent ipsilateral or contralateral breast cancers diagnosed >6 months after primary diagnosis. The authors examined cumulative incidence and second breast cancer rates by primary cancer ER status during 1-5 versus 6-10 years after diagnosis.At 10 years, the cumulative second breast cancer incidence was 11.8% (95% confidence interval [CI], 10.7%-13.1%) for women with ER-negative disease and 7.5% (95% CI, 7.0%-8.0%) for those with ER-positive disease. Women with ER-negative cancer had higher second breast cancer rates than those with ER-positive cancer during the first 5 years of follow-up (16.0 per 1000 person-years [PY]; 95% CI, 14.2-17.9 per 1000 PY; vs. 7.8 per 1000 PY; 95% CI, 7.3-8.4 per 1000 PY, respectively). After 5 years, second breast cancer rates were similar for women with ER-negative versus ER-positive breast cancer (12.1 per 1000 PY; 95% CI, 9.9-14.7; vs. 9.3 per 1000 PY; 95% CI, 8.4-10.3 per 1000 PY, respectively).ER-negative primary breast cancers are associated with a higher risk of second breast cancers than ER-positive cancers during the first 5 years after diagnosis. Further study is needed to examine the potential benefit of more intensive surveillance targeting these women in the early postdiagnosis period.© 2023 American Cancer Society.