568 - Second primary malignancies in patients with breast cancer.

Background

The risk of developing second primary malignancies (SPM) in patients (p) with breast cancer (BC) is higher than among the general population. Tamoxifen, chemotherapy and breast irradiation are associated with an increased risk of SPM. The aim of this study was to investigate the clinicopathological characteristics of the non BC SPM in p with primary diagnostic of BC.

Methods

We conducted a retrospective study in a cohort of 2,111 women with BC diagnosed between 1975 and 2014 in a regional cancer institute in Spain. We evaluated the incidence and pattern of SPM per Warren and Gates criteria, and the impact of breast cancer treatment on SPM.

Results

57p (2.7%) of the cohort developed a SPM, 13 of them (23%) had synchronous tumors and 44p (77%) had metachronous tumors. 10p (18%) developed a third primary malignancy and 1p (1.7%) developed a fourth primary malignancy. The most frequent SPM were hematological malignancies (HM) (11p, 19%), followed by endometrial (7p, 12.3%), gastric (7p, 12.3%), lung (6p, 10.5%), parotid tumors (6p, 10.5%) and melanoma (6p, 10.5%). The mean latency period for SPM was 62.7 months. HM were developed in 0.52% of the cohort of 2,111p. Myeloid neoplasms were diagnosed in 6p (0.28%). Among them, 1p developed chronic myeloid leukemia and 5p developed myelodysplastic syndromes (MDS), including refractory anemia with excess blasts-2 (2p) and 5q minus syndrome (2p). Lymphoid neoplasms were diagnosed in 5p (0.24%). The incidence of HM was similar in both anthracycline-treated and not treated p (0.48% and 0.58%, respectively). The incidence of HM in p treated with radiotherapy was higher than in p who did not receive radiotherapy (0.65% vs 0.19%).

Conclusions

HM are the most frequent non BC SPM in p treated from BC; frequently they are therapy related neoplasms. Deescalating chemotherapy and radiotherapy in BC and finding genetic markers of early malignancy detection are mandatory.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.