Systemic therapy for breast cancer and risk of subsequent contralateral breast cancer in the WECARE Study

Breast Cancer Research

Table 6 Risk ratios of contralateral breast cancer associated with chemotherapy regimen

Chemotherapeutic regimen^b	CBC cases	UBC controls
Chemotherapeutic regimen^b	N (%)	N (%)	RR^a (95 % CI)	Overall P value
No chemotherapy	699 (46)	923 (42)	1.00 (Referent)
Taxanes ± any other chemotherapeutics^c	105 (7)	113 (5)	0.84 (0.57–1.24)
Anthracycline-based regimens^d	291 (19)	381 (17)	0.80 (0.62–1.04)	0.003
CMF^e	321 (21)	629 (28)	0.67 (0.54–0.83)
Other regimens^f	25 (2)	55 (2)	0.55 (0.31–0.97)
Unknown^g	80 (5)	111 (5)

^aAdjusted for age at first breast cancer diagnosis (continuous), first-degree family history of breast cancer (yes, no, unknown), histology (lobular, other, unknown), stage (local, regional, unknown) and estrogen receptor/progesterone receptor status (positive for either, negative, unknown) at first breast cancer diagnosis, radiation therapy (yes, no), and endocrine therapy (yes, no)
^bEach regimen adjusted for the other regimens listed here in addition to all variables listed in footnote “^a”
^cDocetaxel, paclitaxel ± all other chemotherapeutic drugs
^dCyclophosphamide, adriamycin and/or epirubicin alone or in combination with fluorouracil and/or methotrexate. No other chemotherapeutic drugs allowed
^eCyclophosphamide (C) and/or methotrexate (M) and/or fluorouracil (F). No other chemotherapeutic drugs allowed
^fAll other chemotherapeutic drugs and combinations
^gUnknown not included in model
CBC contralateral breast cancer, CI confidence interval, RR risk ratio, UBC unilateral breast cancer

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