Breast cancer detected by screening: the importance of long-term follow-up

This study updates a 10- to 15-year follow-up of 136 patients with breast cancer among 10,187 symptom-free participants in a screening program. Mammography was the sole detection modality in 76 (56%) patients. The combination of mammography and physical examination revealed 41 (30%) cancers, whereas 19 (14%) were detected on physical examination alone. There were 26 (19%) noninvasive and 110 (81%) invasive neoplastic lesions. Positive axillary nodes were found in 34 (25%) patients, and 102 (75%) patients had negative nodes. For the entire group 5- and 10-year survival rates were 84.5% and 75%, respectively. After a minimum follow-up of 10 years and a median of 13.5 years, 102 patients are alive; one of these has a recurrence of cancer. Among the 34 patients who are no longer living, 14 died of causes unrelated to breast cancer. Two patients in the group in which diagnosis was based on mammography alone died of breast cancer, for a breast cancer-related fatality rate of 2.6% (2/76). By contrast, the breast cancer-related mortality of patients whose tumors were palpable at the time of detection was 30% (18/60) (p = 0.00001). This study suggests that long-term survival of patients whose breast cancer is detected by screening is, in large measure, dependent on the ability to detect malignant lesions before they become palpable.