Minimal breast cancer in split region of Croatia on the eve of the National Mammographic Screening Program.

To the Editor: As a result of the worldwide use of screening mammography, many breast biopsies are now performed for small, usually nonpalpable, mammographically detected abnormalities. The breast biopsies of screened abnormalities contain a large number of socalled minimal breast cancers. This term includes all non-invasive cancers (Tis) and invasive cancers up to 1 cm in diameter (minimal invasive cancers, T1a,b) (1,2). In our previous work on the minimal breast cancers in Split region (period 1997–2001), the proportion of Tis and T1a,b cancers was 2.78% and 15.16%, respectively (3). These low proportions were concordant to the proportions of detected minimal breast cancers in developed countries in the prescreening period. Therefore, we advocated the introduction of regional and national breast cancer early detection programs (3). The national breast cancer early detection program started in Croatia in the second half of 2006 under the auspices of Ministry of Health and Social Affairs. The screening method consists of mammography in 50–69-year-old women, with 2-year screening interval. The main goals of this program are reduction in breast cancer mortality for 25% over a 5-year period starting with the introduction of the program, detection of higher percentage of cancers at an early stage, and improvement of the life quality of the patients with breast cancer (4). We wanted to explore basic pathohistologic characteristics of the breast cancer detected in Split region before the introduction of screening program, particularly the presence of the minimal breast cancers that are expected to be increasingly detected during screening program. Therefore, the results presented here may be used in future evaluation of screening success. The pathohistologic data of 2,141 consecutively operated breast carcinomas in Clinical Hospital Center Split in the period from 1997 to 2006 were retrieved from the data base of Institute of Pathology and Cytology, Clinical Hospital Split, Croatia. The data (tumor size, histologic types of invasive and noninvasive tumors, differentiation grade, axillary lymph node status, and hormonal receptor expression) were collected over two 5-year periods (1997–2001 ⁄2002– 2006), and statistically correlated to explore possible changing trends. According to the greatest diameter, the invasive tumors were divided in the following groups: the tumors with the diameter of £2 cm, 2–5 cm, and >5 cm. The cancers with the diameter of £2 cm were additionally divided in T1a,b tumors (diameter of £1 cm; microinvasive carcinomas (T1mic) are also included in this group), and T1c tumors (diameter of 1.1–2 cm) (5). Invasive and non-invasive tumors were histologically classified according to the WHO Classification of breast tumors (5). The grade of invasive tumors was assessed according to Elston and Ellis, and the grade of non-invasive ones according to the classification proposed by a group of European pathologists (6,7). The patients with one or more tumor positive lymph nodes were considered node positive (N+). Estrogen (ER) and progesterone receptor (PgR) status were determined mainly biochemically in the period 1997–2001, using the dextran-coated charcoal method (DCC) with cut-off level of 5 fmol ⁄mg of protein for ER, and 10 fmol ⁄mg of protein for PgR. In the period 2002–2006, the hormonal status was determined immunohistochemicaly using the standard avidin-biotin complex method. ER and PgR were considered positive, if there was nuclear staining in more than 10% of neoplastic cells. Address correspondence and reprint requests to: Joško Bezić, MD, Institute of Pathology, Forensic Medicine and Cytology, Clincal Hospital Center Split, Spinčićeva 1, 21 000 Split, Croatia, or e-mail: [email protected].