Physicians and patients alike are reluctant to use tamoxifen, an adjuvant therapy in the treatment of the very earliest form of breast cancer-ductal carcinoma in situ (DCIS)-because of its side effects, potential complications, and marginal efficacy, according to a study to be published in the journal Cancer.
Tamoxifen is an estrogen hormone-regulating drug used to prevent recurrence of breast cancer after surgery. It has previously been shown to decrease mortality in women with invasive breast cancer. However, in the landmark 1999 study called the National Surgical Adjuvant Breast and Bowel Project (NSABP) B-24, tamoxifen was tested in women with DCIS following breast-conserving surgery.
In contrast to invasive breast cancers, the absolute risk reduction for cancer recurrence was only 5 percent in patients with DCIS, and there was no reduction in mortality. Studies have also shown that tamoxifen increases the risk of endometrial cancer and thromboembolic events, such as pulmonary emboli, particularly in postmenopausal women. Other potential side effects include hot flashes, vaginal bleeding, and cataract formation.
To evaluate the impact of the NSABP B-24 trial on current clinical practice of DCIS, a team of investigators at The University of Texas M. D. Anderson Cancer Center, led by Dr. Tina W.F. Yen, analyzed data from 350 women treated since 1999.
The authors report that physicians did not recommend tamoxifen to all patients with DCIS and patients often refused its use when it was recommended. Only 60 percent of patients were offered tamoxifen for DCIS. Physicians were more likely to recommend tamoxifen for women treated with lumpectomy. Only 54 percent of patients offered the drug chose to take it.
Interestingly, the primary reason patients refused it was for its potential side effects. These same side effects led to a high drop out rate, with only 69 percent of those who initially started the drug after treatment for DCIS still taking it in the most recent follow-up. Newer drugs for DCIS are currently being tested by the NSABP.
SOURCE:
Cancer, March 1, 2004
