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对于接受乳房保留（保乳）肿块切除术治疗的乳腺导管原位癌病例，15年内同侧乳房浸润复发风险大约15%，15年内对侧乳房浸润发生风险大约6%，15年内乳腺癌所致死亡风险大约3%。乳房浸润复发后，乳腺癌所致死亡风险大大增加；不过，大约一半死于乳腺癌的乳腺导管原位癌女性并无浸润复发记录。治疗的双重目标应为预防局部复发并且减少乳腺癌所致死亡。对于乳腺导管原位癌患者，接受乳房切除术与接受肿块切除术而未接受放疗相比，乳腺癌所致死亡风险大致相同，尽管后者局部复发较多。虽然术后辅助放疗可以减少保乳手术后局部浸润复发的风险，但是术后辅助放疗对于此类患者乳腺癌所致死亡风险的影响尚不明确。由于乳腺导管原位癌相关死亡风险低，通过小样本队列研究或随机对照研究很难分析乳腺导管原位癌的死亡风险，故大多数临床研究仅仅分析局部复发。研究死亡风险具有挑战性，因为影响规模很小，有必要对风险特征相似的女性人群进行比较，即必须根据病理特征和治疗变化对风险比进行校正。 2018年8月10日，《美国医学会杂志》网络开放版在线发表加拿大惠仁医院研究所、多伦多大学的大数据研究报告，通过倾向评分匹配法，分析了放疗对于大样本乳腺导管原位癌患者减少乳腺癌所致死亡风险的程度。 该队列研究根据美国18个地区的监测流行病学最终结果（SEER18）登记数据库找出1998～2014年首次被诊断为原发乳腺导管原位癌的女性共计14万366例，摘录诊断时的年龄和年份、种族、收入、肿瘤大小、肿瘤分级、雌激素受体状态、所有治疗（手术和放疗）以及结局（浸润局部复发和乳腺癌所致死亡）等影响因素。根据放疗和（或）手术范围，按1∶1匹配对15年乳腺癌所致死亡风险进行三项两两比较（肿块切除术＋放疗对比肿块切除术；肿块切除术对比乳房切除术；肿块切除术＋放疗对比乳房切除术）并且根据上述影响因素进行校正。 结果发现，其中白人10万9712例（78.2%），平均年龄58.8±12.3岁，接受单纯肿块切除术3万5070例（25.0%）、接受肿块切除术＋放疗6万5301例（46.5%）、接受乳房切除术3万9995例（28.5%）。 经过校正后的精算15年乳腺癌死亡风险：
精算15年乳腺癌死亡风险的三项两两比较：
因此，对于乳腺导管原位癌患者，肿块切除术＋放疗与单纯肿块切除术或单纯乳房切除术相比，乳腺癌死亡风险显著减少，表明放疗的生存获益可能不是由于局部控制，而是由于全身效应。 对此，加拿大麦克马斯特大学的肿瘤学家发表特邀评论：乳腺导管原位癌放疗的全身效应。 JAMA Network Open. 2018 Aug 10;1(4):e181100. Association of Radiotherapy With Survival in Women Treated for Ductal Carcinoma In Situ With Lumpectomy or Mastectomy. Vasily Giannakeas; Victoria Sopik; Steven A. Narod. Women's College Research Institute, Toronto, Ontario, Canada; University of Toronto, Toronto, Ontario, Canada.
QUESTION: Is adjuvant radiation associated with a reduction in breast cancer mortality in patients treated for ductal carcinoma in situ? FINDINGS: Using a matched approach in a large cohort of patients treated for ductal carcinoma in situ, treatment with lumpectomy and radiotherapy was associated with a significantly reduced risk of breast cancer-specific mortality compared with treatment with lumpectomy alone (hazard ratio, 0.77; 95% CI, 0.67-0.88) or mastectomy alone (hazard ratio, 0.75; 95% CI, 0.65-0.87). MEANING: Adjuvant radiation is associated with a small but significant breast cancer survival benefit in patients with ductal carcinoma in situ that cannot be accounted for by enhancing local control. IMPORTANCE: Patients with ductal carcinoma in situ (DCIS) are treated with radiotherapy to reduce their risk of local invasive recurrence after breast-conserving surgery. However, the association of radiotherapy with breast cancer survival in patients with DCIS has not yet been clearly established. OBJECTIVE: To determine the extent to which radiotherapy is associated with reduced risk of breast cancer mortality in a large cohort of patients treated for DCIS, using a propensity score-based matching approach. DESIGN, SETTING, AND PARTICIPANTS: This cohort study of women who had first primary DCIS diagnosed between 1998 and 2014 used data from the Surveillance, Epidemiology, and End Results 18 registries database. Information on age and year of diagnosis, ethnicity, income, tumor size, tumor grade, estrogen receptor status, all treatments (surgery and radiation), and outcomes (invasive local recurrence and death from breast cancer) was abstracted for 140366 women diagnosed with first primary DCIS. Three separate comparisons were performed using 1:1 matching: lumpectomy with radiation vs lumpectomy alone; lumpectomy alone vs mastectomy; and lumpectomy with radiation vs mastectomy. EXPOSURES: Use of radiotherapy and/or extent of surgery. MAIN OUTCOMES AND MEASURES: Crude and adjusted 15-year breast cancer-specific mortality. RESULTS: Of the 140366 patients with DCIS in the cohort (109712 [78.2%] white; mean [SD] age, 58.8 [12.3] years), 35070 (25.0%) were treated with lumpectomy alone, 65301 (46.5%) were treated with lumpectomy and radiotherapy, and 39995 (28.5%) were treated with mastectomy. The actuarial 15-year breast cancer mortality rate was 2.33% for patients treated with lumpectomy alone, 1.74% for patients treated with lumpectomy and radiation, and 2.26% for patients treated with mastectomy. The adjusted hazard ratios for death were 0.77 (95% CI, 0.67-0.88) for lumpectomy and radiotherapy vs lumpectomy alone (29465 propensity-matched pairs), 0.91 (95% CI, 0.78-1.05) for mastectomy alone vs lumpectomy alone (20832 propensity-matched pairs), and 0.75 (95% CI, 0.65-0.87) for lumpectomy and radiotherapy vs mastectomy (29865 propensity-matched pairs). CONCLUSIONS AND RELEVANCE: In patients with DCIS, treatment with lumpectomy and radiotherapy was associated with a significant reduction in breast cancer mortality compared with either lumpectomy alone or mastectomy alone. This suggests that the survival benefit of radiation is likely not due to local control, but rather to systemic effects. DOI: 10.1001/jamanetworkopen.2018.1100 JAMA Network Open. 2018 Aug 10;1(4):e181102. Systemic Effects of Radiotherapy in Ductal Carcinoma In Situ. Mira Goldberg; Timothy J. Whelan. McMaster University, Hamilton, Ontario, Canada. DOI: 10.1001/jamanetworkopen.2018.1102
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