1. ¹Department of Public Health, Erasmus MC, PO Box 2040, Rotterdam 3000 CA, The Netherlands
2. ²Comprehensive Cancer Centre South, PO Box 231, Eindhoven 5600 AE, The Netherlands
3. ³Department of Radiotherapy, Catharina Hospital, PO Box 1350, Eindhoven 5602 ZA, The Netherlands
4. ⁴Department of Surgery, Maxima Medisch Centrum, PO Box 7777, Veldhoven 5500 MB, The Netherlands

Correspondence: Dr I Soerjomataram, E-mail: i.soerjomataram@erasmusmc.nl

Revised 25 May 2006; Accepted 31 May 2006; Published online 27 June 2006.

Abstract

Among 1276 primary breast carcinoma in situ (BCIS) patients diagnosed in 1972–2002 in the Southern Netherlands, 11% developed a second cancer. Breast carcinoma in situ patients exhibited a two-fold increased risk of second cancer (standardised incidence ratios (SIR): 2.1, 95% confidence interval (CI): 1.7–2.5). The risk was highest for a second breast cancer (SIR: 3.4, 95% CI: 2.6–4.3; AER: 66 patients per 10 000 per year) followed by skin cancer (SIR: 1.7, 95% CI: 1.1–2.6; AER: 17 patients per 10 000 per year). The increased risk of second breast cancer was similar for the ipsilateral (SIR: 1.9, 95% CI: 1.3–2.7) and contralateral (SIR: 2.0, 95% CI: 1.4–2.8) breast. Risk of second cancer was independent of age at diagnosis, type of initial therapy, histologic type of BCIS and period of diagnosis. Standardised incidence ratios of second cancer after BCIS (SIR: 2.3, 95% CI: 1.8–2.8) resembled that after invasive breast cancer (SIR: 2.2, 95% CI: 2.1–2.4). Surveillance should be directed towards second (ipsi- and contra-lateral) breast cancer.