L'anàlisi dels factors pronòstic del càncer de mama en un programa de cribratge poblacional

Abstract

BACKGROUND AND OBJECTIVES: The analysis of prognostic factors in all breast cancers diagnosed in the target population and the evaluation of interval tumors as an intermediate outcome measurement is the best approach to assess the benefits of an early detection program. The main aims were to describe and compare the prognostic factors and treatments for breast neoplasms and to evaluate interval cancer. The secondary objectives were to compare the prognostic factors and the treatment of the neoplasms detected in the prevalent and incident screenings and to identify a possible association of age with prognostic factors in these neoplasms. METHODOLOGY: This is a descriptive observational study carried out within the framework of the Early Detection Breast Cancer Screening Program for Sabadell and Cerdanyola (BCSP) of breast cancers in women aged 50-69 of age, classified according to diagnostic setting: screening (diagnosed within the BCSP); healthcare system (diagnosed through ordinary healthcare pathways); or interval (diagnosed outside the BCSP, after a normal mammogram in the BCSP). RESULTS: Of the total 605 neoplasms included, 59 (9.7%) were interval cancer, 321 (53.1%) were diagnosed through ordinary pathways, and 225 (37.2%) though the BCSP. The screening group had higher percentages of in situ tumors, of invasive tumors < 10 mm (24%) and of invasive tumors 10-14 mm (27%). No lymph-node involvement was present in 68% of the tumors diagnosed at screening versus 52.5% in those diagnosed through the healthcare system. Metastases were found in 1.3 % of the tumors diagnosed at screening, in 10.2% of the interval tumors, and in 5.6% of those diagnosed through the ordinary healthcare system. Fifty-seven percent of the tumors diagnosed at screening and 32-25% of the rest were stage I. A predominance (approximately 60%) of stage 0 or I tumors was seen from 1999. A higher percentage of interval tumors and those diagnosed through ordinary healthcare (28.6 % and 22.1%, respectively) scored above 5.4 on the Nottingham Prognostic Index (NPI) with respect to tumors diagnosed at screening (10.99). The percentage of breast-conserving surgery was higher in the group diagnosed at screening (71.1%) versus those in the group diagnosed in the healthcare system (47%) and those in the interval group (37.3). A total of 31 (75.6%) true interval cancers and 10 (24.4%) false-negative interval cancers were detected. The former were diagnosed with greater lymph-node involvement and a higher number of remote metastases. Incident screening diagnosed smaller tumors with less lymph-node involvement and less vascular invasion with slightly higher positivity to hormonal receptors and higher nuclear grade. Breast-conserving surgery was applied in 80% of tumors detected at incident screening and in 57.8% of those found in the prevalent screening. The percentage of neoplasms with NPI >3.4 was nearly the double in women > 60 years of age than in those between 50 and 59 years old. CONCLUSIONS: The neoplasms detected at screening had more favorable prognostic factors than those detected in the other settings. Screening reduced the risk of receiving more aggressive treatment. Interval cancers had worse prognostic factors than those detected through the normal healthcare process, and this difference was even greater with respect to those detected at screening. A higher proportion of neoplasms with lymph-node involvement was observed in the prevalent screening, with greater vascular invasion and tumor size, as well as a significantly higher proportion of neoplasms treated with mastectomy. The prognostic factors of the neoplasms found in the youngest women in the BCSP were less favorable than in the group aged 60-69 years.

Date of Award	19 Dec 2005
Original language	Catalan
Awarding Institution	Universitat Autònoma de Barcelona (UAB)
Supervisor	Xavier Bonfill Cosp (Director)