Breast cancer in systemic sclerosis: Results of a cross-linkage of an Italian Rheumatologic Center and a population-based Cancer Registry and review of the literature.

OBJECTIVE: Increased frequency of few types of cancer in systemic sclerosis (SSc) has been reported in the literature; in particular, breast carcinoma has been proposed as one of the most frequent malignancy in SSc patients, even though data are not univocal. The aim of the present study was to retrospectively evaluate the prevalence of breast cancer in our SSc series, compared with sex-/age-matched general population of the same geographical area, and the possible correlations with SSc features, including X-ray exposure for clinical investigations. A review of the world literature about this topic was also done. METHODS: Clinical records of 318 consecutive SSc patients, 31 M and 287 F, age 51.5±14.5 SD years, disease duration 10±6.5 SD years, referred to our Rheumatology Unit between January 2002 and December 2012 were evaluated. RESULTS: Twelve (3.8%) cases of breast cancer were recorded, including 11/287 females (3.8%) and 1/31 (3.2%) male patients. Considering the subgroup of 202 SSc patients resident in the Province of Modena compared with data of the local Tumor Registry, the incidence of breast cancer observed in our SSc series is significantly higher than expected (SIR 2.1; 95% interval of confidence: 1.13-3.90; p<0.01). On the whole, the comparison between SSc patients with cancer and those without did not show any significant differences with regard to SSc clinical features, including the X-ray exposure. Of note is the relatively shorter disease duration at the time of breast cancer detection (median 2.5years, range 1-21; disease duration of mean 10±6.5 SD years in the entire cohort). The review of the literature revealed that the observed incidence of breast cancer in our case series is comparable to the few studies reporting the highest percentages of this malignancy. CONCLUSIONS: A significant increase of breast cancer incidence compared to sex-age-matched general population from the same geographic area was observed. Moreover, a close temporal relationship between SSc and breast cancer onset was found, independently from clinical, serological, and instrumental features of SSc. The possible pathogenetic link between this systemic autoimmune disease and complicating breast cancer, as well as the results of previous studies, are discussed.