Institute of Cancer Epidemiology, Danish Cancer Society, Copenhagen, Denmark.
Cancer Epidemiol Biomarkers Prev. 2011 Aug;20(8):1784-92. doi: 10.1158/1055-9965.EPI-11-0009. Epub 2011 Jun 8.
Women diagnosed with breast cancer at young age have been shown to be at higher risk of developing a new primary cancer than women diagnosed at older ages, but little is known about whether adjustment for calendar year of breast cancer diagnosis, length of follow-up, and/or breast cancer treatment alters the risk pattern by age.
We identified 304,703 women diagnosed with breast cancer during 1943 to 2006 in the Cancer Registries of Denmark, Norway, and Finland. Relative risks (RR) of subsequent non-breast cancer by age at cancer diagnosis were calculated using Poisson regression models adjusted for country, calendar period, length of follow-up, and treatment. Excess absolute risks (EAR) were also calculated.
The RR for all cancer sites except breast cancer decreased with increasing age both with and without adjustments. The RR and the EAR differed for each age at diagnosis category until the women reached their late 70s. Many specific cancer forms contributed to the overall risk pattern by age with endometrial cancer as 1 exception.
The age at breast cancer diagnosis is an essential risk factor for being diagnosed with a new primary non-breast cancer and the level of risk for specific ages at diagnosis may hold for many years after the diagnosis. Occurrence of endometrial cancer after breast cancer seems to follow a distinct age pattern different from that seen for most other cancer types.
Future studies should aim at exploring the underlying explanations for the age-related findings.
相较于老年确诊乳腺癌的女性，年轻女性确诊乳腺癌后再次发生原发性非乳腺癌的风险更高，但目前尚不清楚，乳腺癌确诊年份、随访时长和/或乳腺癌治疗的校正是否会改变年龄相关的风险模式。
我们在丹麦、挪威和芬兰癌症登记处中，识别了 1943 年至 2006 年间确诊的 304703 例乳腺癌女性。使用泊松回归模型计算了按乳腺癌确诊年龄分层的非乳腺癌部位的相对风险（RR），校正了国家、日历时间、随访时长和治疗。还计算了超额绝对风险（EAR）。
RR 随年龄增长而降低，无论是否校正，除乳腺癌以外的所有癌症部位均如此。RR 和 EAR 在每个诊断年龄类别中均存在差异，直至女性达到 70 多岁。多种特定癌症类型导致了年龄相关的整体风险模式，而子宫内膜癌则是个例外。
乳腺癌的确诊年龄是诊断新原发性非乳腺癌的重要风险因素，且特定诊断年龄的风险水平可能会在诊断后持续多年。乳腺癌后发生子宫内膜癌的情况似乎遵循着与大多数其他癌症类型不同的明确年龄模式。
未来的研究应致力于探索这些年龄相关发现的潜在原因。
