Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MD, USA.
Breast Cancer Res Treat. 2017 Nov;166(1):299-306. doi: 10.1007/s10549-017-4410-6. Epub 2017 Jul 25.
Radiotherapy for ductal carcinoma (DCIS) is increasing, but the risks and benefits of the treatment remain uncertain. We aimed to investigate the relationship between radiotherapy for DCIS and risk of second non-breast cancers in a large US cohort.
We conducted a retrospective cohort study of 52,556 women in 12 U.S. population-based cancer registries diagnosed with first primary DCIS during 1992-2008 at age 25-79 years. We estimated relative risks (RRs), attributable risks (AR), and excess absolute risks (EAR) of second non-breast cancers associated with radiotherapy using Poisson regression adjusted for age at year of diagnosis, grade, hormonal therapy (yes/no or unknown), and time since diagnosis.
Approximately half of the women (46.3%) received radiotherapy. Radiotherapy was associated with an increased risk of all second non-breast cancers combined [RR 1.17, 95% confidence interval (CI) 1.08-1.28] and all in-field, radiation-related second cancers combined (RR 1.37, 95% CI 1.15-1.63), driven by second lung cancers (RR 1.33, 95% CI 1.10-1.60) and non-CLL leukemia (RR 1.71, 95% CI 1.02-2.86). The estimated cumulative excess risk of all second non-breast cancers was 0.8% by 15 years after DCIS diagnosis.
Radiotherapy was associated with an increased risk of second non-breast cancers. The specific excess of cancers at sites likely in/near the radiotherapy field suggests the findings are unlikely due exclusively to confounding, but further research into factors related to receipt of radiotherapy is needed. Our risk estimates can be used to help assess the balance of the risks and benefits of radiotherapy for DCIS and to inform clinical practice.
导管癌（DCIS）的放射治疗正在增加，但治疗的风险和益处仍不确定。我们旨在通过美国的一项大型队列研究来调查 DCIS 放射治疗与第二非乳腺癌风险之间的关系。
我们对 12 个美国人群癌症登记处的 52556 名女性进行了回顾性队列研究，这些女性在 1992 年至 2008 年期间被诊断为年龄在 25-79 岁的第一原发性 DCIS。我们使用泊松回归，根据诊断当年的年龄、分级、激素治疗（是/否或未知）和诊断后时间，估计与放射治疗相关的第二非乳腺癌的相对风险（RR）、归因风险（AR）和超额绝对风险（EAR）。
大约一半的女性（46.3%）接受了放射治疗。放射治疗与所有第二非乳腺癌的风险增加相关（RR 1.17，95%置信区间[CI] 1.08-1.28），以及所有场内、与放射治疗相关的第二癌症的风险增加相关（RR 1.37，95% CI 1.15-1.63），这是由第二肺癌（RR 1.33，95% CI 1.10-1.60）和非慢性淋巴细胞白血病（CLL）白血病（RR 1.71，95% CI 1.02-2.86）驱动的。在 DCIS 诊断后 15 年内，所有第二非乳腺癌的累积超额风险估计为 0.8%。
放射治疗与第二非乳腺癌的风险增加有关。放射治疗场附近或附近部位癌症的特定过量表明，这些发现不太可能完全归因于混杂因素，但需要进一步研究与接受放射治疗相关的因素。我们的风险估计可以用于帮助评估 DCIS 放射治疗的风险和益处的平衡，并为临床实践提供信息。
