Question: In a 35 year old with breast cancer, currently on Tamoxifen, with irregular bleeding, what is the risk of endometrial cancer?
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Answer: No information on the risk of endometrial cancer in a woman aged 35 with breast cancer, taking tamoxifen and with irregular bleeding was found.
Two case-control studies have shown an increased risk of endometrial cancer following tamoxifen treatment of breast cancer in younger aged women:
Swerdlow et al (1) compared treatment information on 813 case patients who had endometrial cancer after their diagnosis for breast cancer and 1067 control patients who had breast cancer but not subsequent endometrial cancer. A statistically significantly higher risk of endometrial cancer was observed for tamoxifen users than for non-users … for patients who were reported to be premenopausal or who were aged younger than 45 years old and had not had an oophorectomy (OR = 2.0, 95% CI = 1.2 to 3.5)
Pukkala et al (2) identified all patients with breast cancer diagnosis since 1980 in Finland who subsequently developed an endometrial cancer by the end of 1995 and 3 matched controls from the 38,000 breast cancer patients of the Finnish Cancer Registry database. They found that young age at breast cancer diagnosis appeared to increase the RR of having tamoxifen-induced endometrial cancer. With a threshold age of 55 years, the OR for the younger stratum (16 cases and 18 controls using tamoxifen) was 4.6 (95% CI 1.4–14, p = 0.01), while the OR for the older stratum (43 cases, 70 controls) was 2.6 (95% CI 1.5–4.5, p = 0.001).
(Evidence level III)
References:
- Swerdlow AJ. Jones ME. British Tamoxifen Second Cancer Study Group. Tamoxifen treatment for breast cancer and risk of endometrial cancer: a case-control study. Journal of the National Cancer Institute. 97(5):375-84, 2005 Mar 2. Full text
- Pukkala E. Kyyronen P. Sankila R. Holli K. Tamoxifen and toremifene treatment of breast cancer and risk of subsequent endometrial cancer: a population-based case-control study. International Journal of Cancer. 100(3):337-41, 2002 Jul 20. Full text
Search date: February 2009
Classification of evidence levels
Ia Evidence obtained from meta-analysis of randomised controlled trials.
Ib Evidence obtained from at least one randomised controlled trial.
IIa Evidence obtained from at least one well-designed controlled study without randomisation.
IIb Evidence obtained from at least one other type of well-designed quasi-experimental study.
III Evidence obtained from well-designed non-experimental descriptive studies, such as comparative studies, correlation studies and case studies.
IV Evidence obtained from expert committee reports or opinions and/or clinical experience of respected authorities.
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