Outcomes in patients with primary breast cancer and a subsequent diagnosis of endometrial cancer : comparison of cohorts treated with and without tamoxifen.
BACKGROUND
The study compared tumor characteristics and survival in women with breast cancer who subsequently developed endometrial cancer with or without a history of tamoxifen use.


METHODS
The British Columbia Cancer Agency registry identified 163 women diagnosed with breast cancer between 1989-1999 who received a subsequent diagnosis of endometrial cancer. Of these, 55% (n = 90) had a history of tamoxifen use. Outcomes analyzed were breast cancer-specific survival (BCSS), endometrial cancer-specific survival (ECSS), and overall survival (OS).


RESULTS
Median follow-up was 9.4 years. Distributions of age, menopausal status, body mass index, and comorbidities were similar in the tamoxifen-treated and nontamoxifen cohorts. Proportions of aggressive endometrial cancer subtypes including papillary serous, clear cell, and mixed mullerian tumors were higher in the tamoxifen cohort (28% vs14%, P = .03). Distributions of endometrial cancer grade and stage were similar in the 2 groups (P > .05). Hysterectomy and/or oophorectomy were the primary treatments for endometrial cancer in 99% of patients, with comparable pelvic control rates in the tamoxifen and nontamoxifen groups. At 10 years, patients in the tamoxifen group experienced lower BCSS compared with the nontamoxifen group (89% vs 97%, P = .02). No significant differences in ECSS and OS were observed between the 2 groups (ECSS 82% and 82%, P = .85; and OS 69% v. 66%, P = .85).


CONCLUSIONS
In patients with breast cancer who developed a subsequent endometrial cancer, tamoxifen-treated patients had higher proportions of aggressive endometrial cancer subtypes, but almost all cases were amenable to surgery, thus resulting in similar endometrial cancer control and survival when compared with nontamoxifen treated patients.
Saadat
Mandana
M
Radiation Therapy Program, British Columbia Cancer Agency, Vancouver Island Centre, University of British Columbia, British Columbia, Canada.
Truong
Pauline T
PT
Kader
Hosam A
HA
Speers
Caroline H
CH
Berthelet
Eric
E
McMurtrie
Elissa
E
Olivotto
Ivo A
IA
D000368:Aged; D001943:Breast Neoplasms / Q000175:diagnosis / Q000188:drug therapy / Q000473:pathology*; D015331:Cohort Studies; D016889:Endometrial Neoplasms / Q000139:chemically induced / Q000175:diagnosis / Q000473:pathology*; D004965:Estrogen Antagonists / Q000009:adverse effects / Q000627:therapeutic use; D005260:Female; D006801:Humans; D008875:Middle Aged; D009367:Neoplasm Staging; D016019:Survival Analysis; D013629:Tamoxifen / Q000009:adverse effects / Q000627:therapeutic use*; D013997:Time Factors; D016896:Treatment Outcome
D004965:Estrogen Antagonists; D013629:Tamoxifen