Department of Radiation Oncology, Dana-Farber Cancer Institute, Boston, MA 02115, USA.
BMJ. 2010 Mar 2;340:c845. doi: 10.1136/bmj.c845.
To determine if the length of interval between breast conserving surgery and start of radiotherapy affects local recurrence and to identify factors that might be associated with delay in older women with breast cancer.
Retrospective cohort analysis with Cox proportional hazards models to study the association between time to radiotherapy and local recurrence, and propensity score and instrumental variable analyses to confirm findings. Logistic regression investigated factors associated with later start of radiotherapy.
Linked database (Surveillance, Epidemiology, and End Results Program-Medicare) in the United States
18 050 women aged over 65 with stage 0-II breast cancer diagnosed in 1991-2002 who received breast conserving surgery and radiotherapy but not chemotherapy.
Local recurrence.
Median time from surgery to start of radiotherapy was 34 days, with 29.9% (n=5389) of women starting radiotherapy after six weeks. Just over 4% (n=734) of the cohort experienced a local recurrence. After adjustment for clinical and sociodemographic factors, intervals over six weeks were associated with increased likelihood of local recurrence (hazard ratio 1.19, 95% confidence interval 1.01 to 1.39, P=0.033). When the interval was modelled continuously (assessing accumulation of risk by day), the effect was statistically stronger (hazard ratio 1.005 per day, 1.002 to 1.008, P=0.004). Propensity score and instrumental variable analysis confirmed these findings. Instrumental variable analysis showed that intervals over six weeks were associated with a 0.96% increase in recurrence at five years (P=0.026). In multivariable analysis, starting radiotherapy after six weeks was significantly associated with positive nodes, comorbidity, history of low income, Hispanic ethnicity, non-white race, later year of diagnosis, and residence outside the southern states of the US.
There is a continuous relation between the interval from breast conserving surgery to radiotherapy and local recurrence in older women with breast cancer, suggesting that starting radiotherapy as soon as possible could minimise the risk of local recurrence. There are considerable disparities in time to starting radiotherapy after breast conserving surgery. Regions of the US known to have increased rates of breast conserving surgery had longer intervals before radiotherapy, suggesting limitations in capacity. Given the known negative impact of local recurrence on survival, mechanisms to ameliorate disparities and policies regarding waiting times for treatment might be warranted.
确定保乳手术后与开始放疗之间的时间间隔是否会影响局部复发，并确定与老年乳腺癌患者延迟治疗相关的因素。
采用 Cox 比例风险模型对接受保乳手术和放疗但未接受化疗的 1991-2002 年诊断为 0 期-II 期乳腺癌且年龄超过 65 岁的 18050 名女性进行回顾性队列分析，以研究放疗时间与局部复发之间的关联，并采用倾向评分和工具变量分析来证实这些发现。Logistic 回归分析了与放疗开始时间较晚相关的因素。
美国监测、流行病学和最终结果计划-医疗保险数据库的链接
18050 名年龄在 65 岁以上、诊断为 0 期-II 期乳腺癌、接受保乳手术和放疗但未接受化疗的女性。
局部复发。
从手术到开始放疗的中位时间为 34 天，29.9%（n=5389）的女性在 6 周后开始放疗。只有略多于 4%（n=734）的患者发生局部复发。在调整了临床和社会人口统计学因素后，6 周以上的间隔与局部复发的可能性增加相关（风险比 1.19，95%置信区间 1.01 至 1.39，P=0.033）。当间隔时间连续建模（按天评估风险积累）时，效果在统计学上更强（每天增加 0.005，1.002 至 1.008，P=0.004）。倾向评分和工具变量分析证实了这些发现。工具变量分析表明，6 周以上的间隔与 5 年时复发率增加 0.96%相关（P=0.026）。多变量分析显示，6 周后开始放疗与阳性淋巴结、合并症、低收入史、西班牙裔、非白种人、较晚的诊断年份以及居住在美国南部以外的地区显著相关。
对于老年乳腺癌患者，从保乳手术到放疗的时间间隔与局部复发之间存在连续关系，这表明尽快开始放疗可以最大程度地降低局部复发的风险。在接受保乳手术后开始放疗的时间存在相当大的差异。美国已知保乳手术率较高的地区在放疗前的间隔时间较长，这表明放疗能力有限。鉴于局部复发对生存的负面影响，可能需要采取减轻差异的机制和有关治疗等待时间的政策。
