Postmenopausal women with estrogen receptor–positive breast cancer treated with aromatase inhibitors prior to surgery may be able to have breast-conserving surgery rather than a mastectomy, according to the results of a national clinical trial.
“We found that half of the postmenopausal women in the study who initially faced having a mastectomy were able to have breast-conserving surgery after being treated for 4 months with an aromatase inhibitor. Preoperative therapy with aromatase inhibitors significantly increases surgical options for women with estrogen-rich cancers,” says co-principal investigator John A. Olson, Jr, MD, PhD, professor and vice chairman of the department of surgery at the University of Maryland School of Medicine and chief of general and oncologic surgery at the University of Maryland Medical Center in Baltimore.
The phase 2 trial, which was conducted by the American College of Surgeons Oncology Group, was led by Matthew J. C. Ellis, MD, BChir, PhD, of Washington University in St. Louis.
In the study, results from 374 patients with stage II and III estrogen receptor–positive tumors were analyzed. Before treatment, 45.7% were candidates for mastectomy, 53.2% were considered for breast conservation surgery, and 1.1% was regarded as inoperable. The women were randomly selected to receive 1 of 3 aromatase inhibitors: anastrozole, exemestane, or letrozole.
Following aromatase inhibitor treatment for 16 weeks, 352 women had surgery:
- 241 women (68.5%) had breast conservation surgery
- 111 had a mastectomy
The group that had breast conservation therapy included 84 of 163 women (51.5%) who originally required mastectomy, according to their surgeon.
“We found it particularly interesting that about one-fourth of the patients who had a mastectomy after being treated with an aromatase inhibitor had evidence of a relatively small tumor when we examined their breast tissue in the laboratory, suggesting that a mastectomy might not have been necessary,” Olson says.
He adds, “Giving aromatase inhibitor therapy preoperatively allows breast conservation surgery in a substantial proportion of patients with estrogen receptor–rich tumors who would otherwise be considered candidates for mastectomy. If we had better techniques to determine how much cancer remains after preoperative treatment and surgeons were willing to attempt breast conservation surgery in patients with responsive tumors, perhaps we could improve the rates of successful breast conservation therapy for these patients.”