Prevention and Cancer Control, Cancer Care Ontario, Toronto, Ontario, Canada.
Eur J Cancer Prev. 2012 Nov;21(6):499-506. doi: 10.1097/CEJ.0b013e328350b0f4.
Most studies reporting more favourable biological features of screen-detected breast cancers compared with symptomatic or interval cancers include initial or prevalent screens and therefore may not indicate the real benefit of screening on breast cancer mortality. We conducted case-case comparisons within a cohort of eligible women (N=771 715) who were aged 50-69 between 1 January 1995 and 31 December 2003. A randomly selected sample of breast cancers (N=1848) diagnosed among these women were compared by detection method. Tumour characteristics of interval cancers (N=362) diagnosed after 6-24 months of a negative screen or symptomatic breast cancers (N=491) were compared with subsequent screen-detected breast cancers diagnosed within 6 months of a positive screen (N=995) using polytomous logistic regression. Tumours were evaluated for clinical presentation, histology and expression of hormone receptors. Women with symptomatic detected [odds ratio (OR)=7.48, 95% confidence interval (CI)=5.38-10.38] and interval cancers (OR=2.20, 95% CI=1.56-3.10) were more often diagnosed at stage III-IV versus I than women with rescreen-detected cancers. After adjusting for tumour size, women with symptomatic cancers had tumours of higher grade (OR=1.50, 95% CI=1.05-2.15) and mitotic score (OR=1.69, 95% CI=1.15-2.49) and women with interval cancers had tumours of higher mitotic score (OR=1.52, 95% CI=1.01-2.28) compared with women diagnosed at screening. Subsequent screen-detected cancers are not only detected at an earlier stage but are also less aggressive, leading to a better prognosis. As long-term mortality reduction for breast screening may depend on subsequent screens, our study indicates that mammography screening can be effective in women aged 50-69.
大多数报道筛查检出乳腺癌比症状性或间期乳腺癌具有更有利生物学特征的研究都包括初始或普遍筛查，因此可能并不能表明筛查对乳腺癌死亡率的真正益处。我们在一个合格女性队列（N=771715）中进行了病例对照研究，这些女性年龄在 50-69 岁之间，时间为 1995 年 1 月 1 日至 2003 年 12 月 31 日。随机选择这些女性中诊断出的乳腺癌（N=1848），并根据检测方法进行比较。对 6-24 个月阴性筛查或症状性乳腺癌（N=491）后诊断出的间期癌（N=362）的肿瘤特征，与在阳性筛查后 6 个月内诊断出的后续筛查检出乳腺癌（N=995）进行比较，采用多分类逻辑回归。对临床表现、组织学和激素受体表达进行肿瘤评估。与再次筛查检出的癌症相比，症状性检出（比值比[OR]=7.48，95%置信区间[CI]=5.38-10.38）和间期癌（OR=2.20，95% CI=1.56-3.10）的女性更常被诊断为 III-IV 期而非 I 期。在调整肿瘤大小后，症状性癌症的女性肿瘤分级更高（OR=1.50，95% CI=1.05-2.15）和有丝分裂评分更高（OR=1.69，95% CI=1.15-2.49），而间期癌的女性肿瘤有丝分裂评分更高（OR=1.52，95% CI=1.01-2.28）与筛查时诊断出的女性相比。后续筛查检出的癌症不仅更早被发现，而且侵袭性更小，预后更好。由于乳腺癌筛查的长期死亡率降低可能取决于后续筛查，因此我们的研究表明，乳腺 X 线筛查对 50-69 岁的女性有效。
