Tabár L, Duffy S W, Vitak B, Chen H H, Prevost T C
Department of Mammography, Central Hospital, Falun, Sweden.
Cancer. 1999 Aug 1;86(3):449-62.
The availability of breast carcinoma data from trials of mammographic screening provides an opportunity to study the natural history of breast carcinoma.
The Swedish Two-County study is a randomized, controlled trial of mammographic screening for breast carcinoma in which 77,080 women were randomized to receive an invitation to mammographic screening and 55,985 were randomized to receive no invitation. During the trial, a total of 2468 breast carcinoma cases were diagnosed. The authors examined the effect of screening on the pathologic attributes of the tumors diagnosed, mortality and survival from breast carcinoma, and the consequences of arresting tumor development by screening.
Screening reduces mortality from breast carcinoma largely through its effect in detecting tumors at a smaller size, decreasing the probability of lymph node metastases, and reducing the opportunity for worsening of the grade of malignancy of the tumor.
Breast carcinoma is not a systemic disease at its inception, but is a progressive disease and its development can be arrested by screening. The point at which the tumor's progression is arrested is crucial. Detection of small (<15 mm) and lymph node negative invasive tumors will save lives and confer an opportunity for less radical treatment. Tumor progression in the preclinical phase occurs more rapidly in women age <50 years, suggesting the need for a shorter screening interval for this group.
乳腺钼靶筛查试验中乳腺癌数据的可得性为研究乳腺癌的自然史提供了契机。
瑞典两县研究是一项针对乳腺癌的乳腺钼靶筛查随机对照试验，其中77080名女性被随机分配接受乳腺钼靶筛查邀请，55985名女性被随机分配不接受邀请。在试验期间，共诊断出2468例乳腺癌病例。作者研究了筛查对所诊断肿瘤的病理特征、乳腺癌死亡率和生存率的影响，以及通过筛查阻止肿瘤发展的后果。
筛查主要通过在肿瘤较小时检测到肿瘤、降低淋巴结转移概率以及减少肿瘤恶性程度恶化的机会来降低乳腺癌死亡率。
乳腺癌在发病初期并非全身性疾病，而是一种进展性疾病，其发展可通过筛查得以阻止。肿瘤进展被阻止的时间点至关重要。检测到小的（<15毫米）且无淋巴结转移的浸润性肿瘤将挽救生命，并为采取不那么激进的治疗提供机会。临床前期肿瘤进展在年龄<50岁的女性中发生得更快，这表明该群体需要更短的筛查间隔。
