“This is an important study. We’ve known for some time that the aromatase inhibitors tend to be better than tamoxifen for postmenopausal women with hormonally sensitive invasive breast cancer. The NSABP B-35 trial asked the same question in ductal carcinoma in situ. These data, which now follow patients for a mean of 8.6 years, suggest that anastrozole may be better than tamoxifen in preinvasive disease when looking at breast cancer–free interval, particularly in younger postmenopausal women,” said Anees B. ­Chagpar, MD, Director, The Breast Center, Smilow Cancer Hospital, Yale University School of Medicine, New Haven.

Dr. Chagpar pointed out that the data show that aromatase inhibitors were similar to tamoxifen across most endpoints, with the exception of contralateral invasive cancers. “This would fit with the concept that perhaps there is a chemopreventive effect in this setting,” she said.

“The side-effect profiles of the two agents are different, and although the authors were not able to show significant differences for many of the categories of symptoms they evaluated, at least these data provide us with another potential agent in our tool box for patients with hormone receptor–positive ductal carcinoma in situ,” Dr. Chagpar commented.

She said that some “intriguing” questions remain: “Why do younger women benefit more from anastrozole? It doesn’t seem to be related to body mass index or compliance, according to the authors who struggled with this question as well,” Dr. ­Chagpar continued.

She remains unconvinced of the clear superiority of anastrozole over tamoxifen or vice versa. “Particularly with a low event rate, I think it is safe to say that anastrozole is at least equivalent to tamoxifen in this setting. It really should be a conversation a woman has with her doctor,” she concluded. ■

Disclosure: Dr. Chagpar reported no potential conflicts of interest.