Berrington de Gonzalez Amy, Wong Jeannette, Kleinerman Ruth, Kim Clara, Morton Lindsay, Bekelman Justin E
Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
Int J Radiat Oncol Biol Phys. 2015 Feb 1;91(2):295-302. doi: 10.1016/j.ijrobp.2014.10.040.
Radiation therapy (RT) techniques for prostate cancer are evolving rapidly, but the impact of these changes on risk of second cancers, which are an uncommon but serious consequence of RT, are uncertain. We conducted a comprehensive assessment of risks of second cancer according to RT technique (>10 MV vs ≤10 MV and 3-dimensional [3D] vs 2D RT) and modality (external beam RT, brachytherapy, and combined modes) in a large cohort of prostate cancer patients.
The cohort was constructed using the Surveillance Epidemiology and End Results-Medicare database. We included cases of prostate cancer diagnosed in patients 66 to 84 years of age from 1992 to 2004 and followed through 2009. We used Poisson regression analysis to compare rates of second cancer across RT groups with adjustment for age, follow-up, chemotherapy, hormone therapy, and comorbidities. Analyses of second solid cancers were based on the number of 5-year survivors (n=38,733), and analyses of leukemia were based on number of 2-year survivors (n=52,515) to account for the minimum latency period for radiation-related cancer.
During an average of 4.4 years' follow-up among 5-year prostate cancer survivors (2DRT = 5.5 years; 3DRT = 3.9 years; and brachytherapy = 2.7 years), 2933 second solid cancers were diagnosed. There were no significant differences in second solid cancer rates overall between 3DRT and 2DRT patients (relative risk [RR] = 1.00, 95% confidence interval [CI]: 0.91-1.09), but second rectal cancer rates were significantly lower after 3DRT (RR = 0.59, 95% CI: 0.40-0.88). Rates of second solid cancers for higher- and lower-energy RT were similar overall (RR = 0.97, 95% CI: 0.89-1.06), as were rates for site-specific cancers. There were significant reductions in colon cancer and leukemia rates in the first decade after brachytherapy compared to those after external beam RT.
Advanced treatment planning may have reduced rectal cancer risks in prostate cancer survivors by approximately 3 cases per 1000 after 15 years. Despite concerns about the neutron doses, we did not find evidence that higher energy therapy was associated with increased second cancer risks.
前列腺癌的放射治疗（RT）技术正在迅速发展，但这些变化对第二癌症风险的影响尚不确定，第二癌症是RT一种虽不常见但严重的后果。我们在一大群前列腺癌患者中，根据RT技术（>10MV与≤10MV以及三维[3D]与二维[2D]RT）和治疗方式（外照射放疗、近距离放疗及联合方式），对第二癌症风险进行了全面评估。
该队列使用监测、流行病学和最终结果-医疗保险数据库构建。我们纳入了1992年至2004年66至84岁被诊断为前列腺癌且随访至2009年的患者。我们使用泊松回归分析，在对年龄、随访、化疗、激素治疗和合并症进行调整后，比较各RT组的第二癌症发生率。对第二实体癌的分析基于5年幸存者数量（n = 38,733），对白血病的分析基于2年幸存者数量（n = 52,515），以考虑与辐射相关癌症的最短潜伏期。
在5年前列腺癌幸存者平均4.4年的随访期间（2D RT = 5.5年；3D RT = 3.9年；近距离放疗 = 2.7年），诊断出2933例第二实体癌。3D RT和2D RT患者总体上第二实体癌发生率无显著差异（相对风险[RR] = 1.00，95%置信区间[CI]：0.91 - 1.09），但3D RT后第二直肠癌发生率显著更低（RR = 0.59，95% CI：0.40 - 0.88）。高能和低能RT的第二实体癌发生率总体相似（RR = 0.97，95% CI：0.89 - 1.06），特定部位癌症的发生率也相似。与外照射放疗相比，近距离放疗后第一个十年结肠癌和白血病发生率显著降低。
先进的治疗计划可能使前列腺癌幸存者15年后直肠癌风险每1000例降低约3例。尽管对中子剂量存在担忧，但我们未发现高能治疗与第二癌症风险增加相关的证据。
