Drug Therapy Before Surgery Shrinks Breast Cancer Tumors

Estrogen-lowering drugs help breast cancer patients avoid mastectomies

(RxWiki News) Women with large breast cancer tumors usually have two options - have chemotherapy to shrink the tumor before a lumpectomy - or have the entire breast removed. Now there are gentler options.

Researchers have shown that estrogen-lowering drugs - known as aromatase inhibitors - can be used to shrink tumors in some patients with larger tumors found in stage 2 or 3 breast cancer.

This is great news for post-menopausal women who have estrogen-receptor positive breast cancer, a form of the disease that feeds off estrogen. These estrogen-lowering medicines do what chemotherapy used to do: decrease the size of the tumor so lumpectomies can be performed instead of mastectomies.

"Estrogen-lowering drugs help some breast cancer patients avoid chemotherapy and mastectomies."

“At the beginning [of the study], all of these patients were going to get mastectomy, and at the end of the trial only half got mastectomy,” says Matthew J. Ellis, MD, PhD, of Washington University School of Medicine in St. Louis and principal investigator of the trial conducted by the American College of Surgeons Oncology Group. “That’s a very substantial improvement in surgical outcomes.”

The study also found the drugs shrunk tumors in a large number of women who were considered unlikely candidates for breast conserving surgery because the operations would be too disfiguring. These women were also spared mastectomies.

Aromatase inhibitors even worked for four women who were orginally considered to have inoperable cancer where a mastectomy wouldn't get all the cancer. These women, too, were able to have lumpectomies.

Beyond the surgical benefits, aromatase inhibitors aren't nearly as toxic as traditional chemotherapy. And for post-menopausal women with ER+ breast cancer, it is well established that aromatase inhibitors are more active in preventing relapses than chemotherapy, Ellis says.

Despite the overall success of the trial, Ellis points out that many women still had to have mastectomies because their tumors did not respond to the aromatase inhibitor treatment.

“The biggest question in my mind is how best to treat the aromatase inhibitor-resistant patients,” he says. “These patients have poor outcomes and currently there is no known targeted therapy for them. The question of aromatase inhibitor resistance is a critical issue to understand and address therapeutically.”

The results appeared online in the May 9, 2011 edition of the Journal of Clinical Oncology.

The Study

  • 352 women were randomly assigned to receive one of three FDA-approved aromatase inhibitors
  • Letrozole, anastrozole and exemestane were assigned to the groups and taken for 16 weeks
  • Letrozole and anastrozole were slightly better than exemestane in shrinking tumors
  • 159 women were originally told they required mastectomy
  • Tumors in 81 women shrunk to the point they were able to have breast-conserving surgery
  • Of 189 women considered “marginal” for breast conservation, 83 percent were able to undergo breast conserving-surgery
  • Four patients originally classified as inoperable also had breast-conserving surgery
Review Date: 
May 11, 2011