Mammographic screening reduces risk of breast carcinoma recurrence.

Background: The current report is a long-term evaluation of breast carcinoma recurrence, factors predicting recurrence, and postrecurrence prognosis in relation to patients' use of service screening, which has been provided in Turku, Finland, since 1987 for women ages 40-74 years.

Methods: The current study included 527 invasive breast carcinomas: 418 in the screening group (which included screen-detected and interval malignancies) and 109 in the nonscreening group (which included breast carcinomas detected before initial screening and those detected in patients who chose not to undergo screening). These breast carcinomas were diagnosed among women ages 40-74 years between 1987 and 1993, with follow-up extending until the end of 2001.

Results: In the screening group, the risk of recurrence was only approximately half of the corresponding risk in the nonscreening group (hazard ratio [HR], 0.57; 95% confidence interval [CI], 0.39-0.83; P = 0.003). Five years after the primary diagnosis, 16% of patients in the screening group and 28% of patients in the nonscreening group (P = 0.001) had experienced recurrence; 10 years after diagnosis, the corresponding rates were 21% and 34%, respectively (P = 0.001). Postrecurrence prognosis was comparable for both detection groups (HR, 1.17; 95% CI, 0.70-1.94; P = 0.551), with approximately half of all patients dying of disease 5 years after recurrence. Detection of breast carcinoma via a method other than mammographic screening was associated with a high risk of recurrence on univariate analysis. On Cox multivariate analysis, risk factors for recurrence included lobular histologic type (HR, 2.23; 95% CI, 1.44-3.48; P < 0.001), poor histologic grade (HR, 2.02; 95% CI, 1.20-3.39; P = 0.008), and large tumor size (HR, 1.60; 95% CI, 1.07-2.37; P = 0.021).

Conclusions: Long-term data from a population-based program demonstrated that mammographic screening reduced patients' risk of breast carcinoma recurrence. Specifically, the risk for patients with screen-detected disease was only approximately half of the risk for patients with non-screen-detected disease. Nonetheless, postrecurrence prognosis was comparable for patients in both detection groups.