Increased risk of second malignancies after in situ breast carcinoma in a population-based registry

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.

The occurrence of invasive cancers following a diagnosis of breast carcinoma in situ

“…Thus, the well-studied effects of radiotherapy appear to hold true in an observational setting. However, our findings are in contrast with those of Soerjomataram et al (2006), who found (also in an observational setting) that both ipsilateral and contralateral invasive breast cancer risks were slightly higher in BCIS patients who received radiotherapy.…”

“…On the other hand, Franceschi et al (1998) found no excess risk at any cancer site other than the breast. Soerjomataram et al (2006) studied subsequent ipsilateral and contralateral breast cancers separately, and found the increased risks to be similar (SIR for ipsilateral 1.9; contralateral 2.0) -although each of these figures was based on a per-person rather than per-breast calculation and should therefore be doubled in order to be directly comparable with our SIR estimates.…”

“…This was Increased occurrence of breast cancer following BCIS has been shown in a number of previous studies from around the world: from Sweden (Wärnberg et al, 2000;Rawal et al, 2005); Switzerland (Franceschi et al, 1998;Levi et al, 2005); The Netherlands (Soerjomataram et al, 2006); and the United State of America (Ward et al, 1992;Habel et al, 1997;Claus et al, 2003). Soerjomataram et al (2006) also found an increased occurrence of skin cancer (SIR 1.7; 95% CI 1.1 -2.6) following BCIS, whereas Ward et al (1992) found that (apart from breast cancer) colorectal, cervical and endometrial cancers were the most prevalent in BCIS patients. On the other hand, Franceschi et al (1998) found no excess risk at any cancer site other than the breast.…”

“…A number of previous studies have focused on the risk of second breast cancer following a diagnosis of BCIS (Habel et al, 1997;Wärnberg et al, 2000;Claus et al, 2003;Levi et al, 2005;Rawal et al, 2005), with estimates of relative risk generally of the order of two-to fivefold. Few studies have looked at the occurrence of subsequent invasive cancers at other sites (Ward et al, 1992;Franceschi et al, 1998;Soerjomataram et al, 2006), and these were based on relatively small numbers of cases. …”

‘Second primary breast cancers following an initial diagnosis of cancer in one breast: a methodological issue’

“…Rawal et al (2005) analysed ipsilateral and contralateral breast cancers separately, but it appears that mastectomies were not accounted for. Similarly, Soerjomataram et al (2006) calculated expected numbers and SIRs for breast cancer following breast carcinoma in situ separately for ipsilateral and contralateral tumours, but it is not clear whether they allowed for mastectomies. Moreover, they applied the overall incidence rates from the general population to each group (rather than half-rates), thus leading to expected numbers which were twice, and SIRs which were half, the true values.…”