> Table 46: Tamoxifen in the treatment of ductal carcinoma in situ (DCIS)
This summary table contains detailed information about research studies. Summary tables offer an informative look at the science behind many breast cancer guidelines and recommendations. However, they should be viewed with some caution. In order to read and interpret research tables successfully, it is important to understand some key concepts. Learn how to read a research table.
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Introduction: Ductal carcinoma in situ (DCIS) is a non-invasive breast cancer. In DCIS, abnormal cells are contained in the
milk ducts. It is called “in situ” (which means "in place") because the cells have not left the milk ducts to invade nearby breast tissue.
Results from one randomized controlled trial showed tamoxifen can lower the risk of invasive and non-invasive breast cancer, both in the same breast treated for DCIS and in the opposite breast, in women with DCIS who have lumpectomy plus radiation [1].
A second randomized controlled trial found tamoxifen did not lower the risk of invasive cancer in the same breast, but did lower the risk of invasive cancer in the opposite breast. In contrast, findings from this trial showed tamoxifen lowered the risk of DCIS recurrence in the same breast, but did not lower the risk of DCIS in the opposite breast [2].
Study selection criteria: Large randomized controlled trials.
Table note: Relative risk above 1 indicates increased risk. Relative risk below 1 indicates decreased risk.
Study
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Study Population
(number of participants)
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Follow-up
(years)
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Absolute Risk of Invasive Breast Cancer per year
(number of cases per 1,000 women)
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Relative Risk of Invasive Breast Cancer in Women Taking Tamoxifen Compared to Women Not Taking Tamoxifen,
RR (95% CI)
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Among Women Not Taking Tamoxifen
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Among Women Taking Tamoxifen
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Randomized controlled trials
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National Surgical Adjuvant Breast and Bowel Project, Protocol B-24 [1]
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1,799 women with DCIS treated with lumpectomy plus radiation
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17.3
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18.8 per
1,000
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6.0 per
1,000
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0.68
(0.49-0.95)*
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UK Coordinating Committee on Cancer Research [2]
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1,576 women with DCIS treated with lumpectomy either with or without radiation
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12.7
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†
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†
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0.81
(0.59-1.12)‡
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* Relative risk for invasive breast cancer in the same breast treated for DCIS. Relative risk for invasive breast cancer in the opposite breast was similar, 0.68 (0.48-0.95).
† Absolute risk not given. However, there was no statistically significant difference between rates of invasive breast cancer for women not taking tamoxifen and women taking tamoxifen (9.1% vs. 8.5%).
‡ Total invasive breast cancer (most breast cancers occurred in the same breast treated for DCIS)
References
1. Wapnir IL, Dignam JJ, Fisher B, et al. Long-term outcomes of invasive ipsilateral breast tumor recurrences after lumpectomy in NSABP B-17 and B-24 randomized clinical trials for DCIS. J Natl Cancer Inst. 103(6):478-88, 2011.
2. Cuzick J, Sestak I, Pinder SE, et al. Effect of tamoxifen and radiotherapy in women with locally excised ductal carcinoma in situ: long-term results from the UK/ANZ DCIS trial. Lancet Oncol. 12(1):21-9, 2011.
Updated 01/13/12
